Distribution of Glycoconjugates in the Kidney Studied by Use of Labeled Lectins

Distribution of glycoconjugates in different areas of the rat kidney was studied by light and electron microscopy using six different horseradish peroxidase-labeled lectins. Glomeruli and brush borders of the proximal tubules reacted differently to these lectins, which indicated differences in the carbohydrate compositions of those regions. The ascending limb of Henle's loop (ALH) had strong binding sites for peanut agglutinin (PNA) and soybean agglutinin (SBA). Dolichos biflorus agglutinin (DBA) did not stain the cells of ALH but did stain those of distal convoluted tubules (DCT). DBA is a good marker for distinguishing ALH from DCT. DBA, PNA, and SBA were also good markers of the collecting duct. Ricinus communis agglutinin (RCA-1) and wheat germ agglutinin (WGA) diffusely stained the various components of different parts of the kidney.

Immunoelectron-microscopic detection of globotriaosylceramide accumulated in the skin of patients with Fabry disease

BACKGROUND

Fabry disease is characterized by the systemic accumulation of glycosphingolipids, particularly in the lysosomes of vascular endothelial cells of most organs due to the deficient activity of alpha-galactosidase A. The major glycolipid accumulated in tissue is globotriaosylceramide (GL-3). To date, no direct detection of GL-3 by immunoelectron microscopy has been reported.

OBJECTIVES

To examine whether GL-3 is accumulated exclusively in lysosomes of cutaneous cells using an anti-GL-3 monoclonal antibody (mAb) and immunoelectron microscopy.

METHODS

Skin specimens from seven patients with Fabry disease were examined immunohistochemically by light and electron microscopy using an anti-GL-3 mAb.

RESULTS

By light microscopy, the cytoplasm of vascular endothelial cells, eccrine gland cells, and perineurium was stained with mouse anti-GL-3 antibody. Electron microscopically, positive signals for GL-3 were limited to dilated lysosomes in the cytoplasm of endothelial cells, pericytes, eccrine gland cells, dermal fibroblasts and perineurium.

CONCLUSIONS

Our results demonstrate that the cytoplasmic deposit in Fabry disease was GL-3 and the accumulated GL-3 was localized essentially to lysosomes.

Expression of epithelial growth factor receptor and its two ligands, transforming growth factor-alpha and epithelial growth factor, in normal and neoplastic squamous cells in the vulva: an immunohistochemical study

Epithelial growth factor receptor (EGFR) sends signals to the proliferation signal transduction system, receiving two ligands: epithelial growth factor (EGF) and transforming growth factor-alpha (TGF-alpha). This immunohistochemical study examined the roles of EGFR and its ligands in the proliferation of normal and neoplastic vulvar squamous cells in 25 patients with vulvar squamous cell carcinoma (VSCC), 10 patients with vulvar condyloma acuminata (VCA), 15 patients with vulvar intra-epithelial neoplasm I-II or III (VIN I-II or III), and 5 subjects with vulvar normal squamous cells (VNSC). EGFR was detected in a few basal cells in 40% of the VNSC, in highly dysplastic cells in 40% of the VIN III, in many neoplastic cells in 80% of the VCA, and in some malignant cells in 64% of the VSCC. EGF was seen in the cytoplasm in 20% of the VIN I-II, 100% of the VIN III, 100% of the VCA, and 100% of the VSCC. Diffuse TGF-alpha was weakly expressed in the cytoplasm in 100% of the VNSC, more intensely in 100% of the VIN and 100% of the VCA, and intensely in 100% of the VSCC. These findings led to the suggestion that the TGF-alpha-EGFR system maintains the growth of normal squamous cells and, in part, maintains the growth of dysplastic and neoplastic squamous cells in the vulva. EGF expression was an early sign of neoplasia. The expression of EGFR with overexpression of its two ligands contributed to the proliferation of dysplastic and neoplastic squamous cells in VIN III and VCA. EGFR expression appeared to contribute to essential neoplastic abnormalities in 64% of the VSCC.

Ultrastructural localization of basigin in normal human epidermis

Basigin is a glycosylated transmembrane protein belonging to the immunoglobulin superfamily. It is thought to play roles in intercellular recognition involved in cell differentiation. We previously demonstrated at the light microscope level a correlation between basigin expression and epidermal differentiation. In the present study, the ultrastructural localization of basigin in normal human epidermal keratinocytes was investigated by immunoelectron microscopy. The basigin labeling was strongest on membranes of basal cells, weaker on prickle cells, and absent in granular and horny cells. On the membrane of basal cells, labeling was observed on the apical and lateral sides but not on the dermal side. Gold particles were mostly observed on the surface of microvilli, especially on their tips. There were fewer on the intermicrovillous membrane and they were absent on the desmosome. These results are consistent with our previous report that basigin expression is correlated with differentiation of epidermal keratinocytes. Microvilli on basal and suprabasal keratinocytes might play roles in the differentiation of keratinocytes through basigin on the tips of microvilli.

The expression of gastric H+-K+-ATPase mRNA and protein in developing rat fundic gland

The proton pump H+-K+-ATPase is the final common pathway mediating the production and secretion of hydrochloric acid by gastric parietal cells. The present studies were undertaken to examine whether the expression of gastric H+-K+-ATPase mRNA and protein changes are associated with the development of H+-K+-ATPase activity in the rat fundic gland. H+-K+-ATPase activity was examined in rat fundic gland at different stages from gestational day 18.5 to postnatal 8 weeks. The expression of H+-K+-ATPase mRNA was detected by in situ hybridization using a digoxigenin-labelled RNA probe with a tyramide signal amplification system. The expression of H+-K+-ATPase protein was evaluated by immunoblotting and immunohistochemistry using antibodies against H+-K+-ATPase alpha- and beta-subunits. We found that H+-K+-ATPase enzyme activity was detectable from the onset of gland formation (day 19.5 of gestation) and increased with age in the developing rat fundic gland. Expression of mRNA and protein was also discernible at the same time, and a progressive increase in expressions was observed as rats developed. Our results suggested that in developing rat fundic gland, the expression of both mRNA and protein of H+-K+-ATPase increased with age in a manner that parallels the development of H+-K+-ATPase enzyme activity.

Expression of N-acetylglucosamine residues in developing rat fundic gland cells

The development of rat fundic gland was studied by immunohistochemistry using a recently developed monoclonal antibody, HIK 1083, at both light and electron microscope levels. Antibody HIK 1083 recognized oligosaccharides with a non-reducing terminal alpha-linked N-acetylglucosamine (GlcNAc) residue. In the developing rat fundic gland, cells expressing alpha-GlcNAc residues were discernible from day 19.5 of gestation and continued to exist till adult. The distribution of the alpha-GlcNAc expressing cells was consistent with that described previously for cells reacting to Griffonia simplicifolia lectin (GSA-II) in all developmental stages. These cells were located at the bottom of the fundic gland when they first appeared. With the elongation and maturation of the gland, these cells moved upwards and were finally restricted in the neck region of the gland. Combining previous reports and the present electron microscopical observations, HIK 1083-positive cells in the adult rat fundic gland are mucous neck cells. The interaction between antibody HIK 1083 and GSA-II lectin was investigated. GSA-II prevented the subsequent binding of HIK 1083, while HIK 1083 did not prevent GSA-II binding to mucous neck cells. Our results suggested that alpha-GlcNAc residues exist in rat fundic gland from day 19.5 of gestation and continue to exist till adult. Cells expressing alpha-GlcNAc residues appeared as typical mucous neck cells from postnatal four weeks.

Coexistence of gland mucous cell-type mucin and lysozyme in gastric gland mucous cells

Class III mucin, identified by paradoxical concanavalin A staining, is confined to gastric gland mucous cells and is an essential component of the gastric surface mucous gel layer. The pretreatment required has hampered the application of this method to electron microscopic studies. Antibody HIK1083 reacts selectively with class III mucins. The present study was undertaken to explore, electron microscopically, the immunoreactivity of the human stomach to HIK1083. We examined normal mucosa from resected human stomachs (five cases; formalin-fixed, paraffin-embedded) and gastric biopsy specimens from patients with early gastric cancer [nine cases; glutaraldehyde- and osmium-fixed, epoxy-embedded (seven cases) and half-strength Karnovsky's solution-fixed, Lowicryl K4M-embedded (two cases)]. Immunostaining with HIK1083 and anti-lysozyme antibody was examined under light and electron microscopes. Gland mucous cells were labeled with HIK1083, and lysozyme was detected in some gland mucous cells and surface mucous cells. Electron microscopically, the secretory granules of gland mucous cells contained a single electron-dense core. HIK1083-positive mucins and lysozyme coexisted in the secretory granules of gastric gland mucous cells. HIK1083-reactive mucins and lysozyme were distributed in the matrix and in the dense core of these secretory granules, respectively. HIK1083 can be used for electron immunohistochemistry.

Immunohistochemical study of MUC1 mucin in premalignant oral lesions and oral squamous cell carcinoma: association with disease progression, mode of invasion, and lymph node metastasis

BACKGROUND

MUC1 mucin is a transmembrane, mucin-like glycoprotein encoded by the MUC1 gene. Although MUC1 expression has been identified in a variety of neoplastic tissues, to the authors' knowledge, few studies have examined MUC1 expression in premalignant and malignant oral lesions.

METHODS

A total of 36 specimens of oral epithelial dysplasia, 12 carcinoma in situ (CIS) specimens and 77 specimens of oral squamous cell carcinoma (OSCC), were examined by both light and electron microscopy using immunohistochemical staining of MUC1 mucin. Relations between staining patterns and clinicopathologic findings also were examined.

RESULTS

Distinct membrane MUC1 mucin staining patterns were identified in epithelial dysplasia (33.0%), CIS (50.0%), and OSCC (59.7%) cases. A predominantly cytoplasmic staining pattern was detected in epithelial dysplasia (5.6%), CIS (41.7%), and OSCC (32.5%) cases. Significant positive correlations were found between MUC1 mucin membranous immunoreactivity and disease progression from epithelial dysplasia to OSCC (P < 0.01), mode of tumor invasion (P < 0.02), and lymph node metastasis (P < 0.01). Furthermore, the malignant transformation of oral epithelium, tumor invasion, and tumor metastasis were associated with higher MUC1 mucin expression in the cytoplasm (P < 0.01). In addition to the usual cell surface expression, cytoplasmic expression of MUC1 mucin was confirmed by colloidal gold labeling with transmission electron microscopy.

CONCLUSIONS

The results of the current study suggest that determination of MUC1 mucin expression may be a parameter in the diagnosis of premalignant and malignant lesions arising in the oral cavity and that this expression may affect the malignant behavior of OSCC. MUC1 mucin expression may be a useful diagnostic marker for prediction of the invasive/metastatic potential of OSCC.

Fabry disease: ultrastructural lectin histochemical analyses of lysosomal deposits

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism resulting from a deficiency of lysosomal alpha-galactosidase activity. Globotriaosylceramide accumulates predominantly in lysosomes of various tissues. Former studies have clarified the nature of this disease, and the accumulated materials in the lysosomes have been analyzed using biochemical techniques. In the present study, transmission electron microscopy was used to reveal the fine structure of these lysosomal deposits, and sugar residues in the lysosomal deposits in Fabry disease were examined by lectin histochemistry combined with enzyme digestion. This is the first report to describe the lysosomal sugar residues in Fabry disease analyzed using lectin histochemistry at the ultrastructural level. With these techniques, we were able to detect alpha-galactosyl, beta-galactosyl and glucosyl sugar residues in the lysosomal deposits. The experimental procedures used in this study have considerable potential for use in investigations of glycolipid and glycoprotein storage diseases without the need for complex methodology and expensive materials.

Sulfated glycosaminoglycans in guinea pig neutrophils studied by use of cationic colloidal gold

Using a high electron resolution staining method, cationic colloidal gold (CCG, pH 1.0) staining, we studied the fine structural localization of sulfated glycosaminoglycans (GAGs) in various maturational stages of guinea pig neutrophils. Azurophil and specific granules of neutrophils reacted positively to CCG, with variety in labeling according to maturation. All immature azurophil and specific granules were labeled selectively. Mature granules lost their affinity with CCG. CCG-positive labeling was also observed in the trans to trans-most Golgi apparatus of promyelocytes and myelocytes. Prior absorption with poly-l-lysine prevented CCG labeling of tissue sections. Mild methylation of ultrathin sections at 37C did not alter CCG labeling, whereas CCG labeling disappeared after active methylation at 60C. Treatment with chondroitinase ABC or heparinase I abolished the majority of CCG labeling. These findings suggest the existence of sulfated GAGs not only in immature azurophil but also in immature specific granules of neutrophils. Sulfation of GAGs occurs in the trans- to trans-most Golgi apparatus of neutrophil granulocytes. A possible correlation between accumulation of sulfated GAGs and maturation of specific granules in neutrophils is also discussed.

Keratan sulfate glycosaminoglycans in murine eosinophil-specific granules

We examined the presence of sialyl glycoconjugates in specific granules from murine bone marrow eosinophils. Lectin cytochemistry using Maackia amurensis lectin II (MAL II) specific for sialyl alpha-2,3 galactose residues demonstrated positive labeling in both immature and mature specific granules. Pretreatment with Clostridium neuraminidase or keratanase II eliminated the positive labeling of MAL II in the specific granules. High iron diamine-thiocarbohydrazide-silver proteinate physical development (HID-TCH-SP-PD) staining, which is specific for sulfated glycoconjugates, also positively labeled immature specific granules lacking crystalloids but not mature granules with crystalloids. Pretreatment with a combination of chondroitinase ABC and keratanase, or a combination of chondroitinase ABC and keratanase II, eliminated the positive labeling obtained with HID-TCH-SP-PD. These results indicate that the sialyl residues detected by MAL II are expressed as terminal sugar residues of keratan sulfate proteoglycan, which appears to be of the corneal type in view of its sensitivity to keratanase and keratanase II. (J Histochem Cytochem 47:481-488, 1999)

Ontogeny of the rat parietal cell: analysis using anti-parietal cell antibody and transmission electron microscopy

We studied the ontogeny of the rat parietal cell using human anti-parietal cell antibody and transmission electron microscopy. In the gastric fundus of the rat, we found that the epithelium changed from stratified to columnar at gestational day 18.5. Gastric pits began to form at gestational day 19.5. Primitive fundic glands appeared at gestational day 20.5. Human anti-parietal cell antibody specifically stained the rat parietal cells. By this immunohistochemical staining, rat parietal cells were identified from gestational day 19.5. At first we observed only a few plump parietal cells sparsely located in the fundic glands. In neonatal rats, the parietal cells increased in number and began to distribute themselves over a wider area of the primitive fundic glands especially in the lower half. As the rats grew, the distribution area of the parietal cells expanded to cover the whole of the glands except for the foveolar region. Parietal cells in the isthmus and neck regions were round and plump, while those in the basal region were slender and polygonal. We found that throughout the development of the fundic glands there were several ultrastructural changes of the parietal cells. In the late fetal period, parietal cells containing lysosomes and secretory granules were observed, but no tubulovesicles were identified. Development of the tubulovesicles was remarkable until one week after birth. The ultrastructure of the parietal cells of the neonate and adult varied, depending on their distribution area. We found that parietal cells in the basal region of the fundic glands which are fully matured cells had wider intracellular secretory canaliculi, while cells in the upper region had narrower canaliculi; this indicates the functional difference between hydrochloric acid secretion in parietal cells of the two regions.

Sulphated glycosaminoglycans in guinea pig eosinophils studied by means of cationic colloidal gold

Using bone marrow embedded in hydrophilic resin Lowicryl K4M and cationic colloidal gold pH 1.0 labelling, we studied sites of sulphation and sulphated glycosaminoglycans ultrastructurally in various maturational stages of both eosinophil granulocytes and eosinophil granules of guinea pig. Eosinophil granules reacted positively to cationic gold, the pattern of labelling varying according to the degree of cell maturation. The formation of eosinophil granules takes place throughout the myelocyte stage. Early eosinophil myelocytes contain a large Golgi apparatus with active granulogenesis, while late ones contain a small and less active Golgi apparatus. All the immature granules were labelled positively. However, mature granules with a central crystal bar lost their affinity towards colloidal gold. Interestingly, strong colloidal gold labelling was also observed in the trans to transmost Golgi apparatus, especially in immature eosinophil granulocytes. This indicates that sulphation of glycosaminoglycans occurs in the trans to transmost Golgi apparatus of eosinophil granulocytes. Prior absorption with poly-L-lysine prevented colloidal gold labelling of tissue sections. Methylation of sections at 37 degrees C did not alter the gold labelling, whereas the labelling disappeared after methylation at 60 degrees C. Prior treatment with chondroitinase ABC or heparinase I abolished the majority of colloidal gold labelling in immature eosinophil granules. Taking these results together, we conclude that immature eosinophil granules contain sulphated glycosaminoglycans including chondroitin sulphate or heparan sulphate or both.

Immunocytochemistry and in situ hybridization studies of pepsinogen C-producing cells in developing rat fundic glands

The ontogeny of pepsinogen C-producing cells in rat fundic glands was studied by means of light and electron microscopy using an antiserum raised against a synthetic peptide based on rat pepsinogen C. To confirm the immunocytochemistry results, the expression of rat pepsinogen C messenger RNA (mRNA) in the fundic gland was also examined by in situ hybridization using a digoxigenin-labeled RNA probe. In adult rats, pepsinogen C was produced by chief cells, mucous neck cells, and intermediate mucopeptic cells. Pepsinogen C-producing cells appeared in embryos as early as 18.5 days' gestation. The development of these cells could be classified into four stages: (1) 18.5 days' gestation to 0.5 days after birth; (2) 0.5 days to 2 weeks after birth; (3) 3-4 weeks after birth; (4) 4-8 weeks after birth. In embryos and young animals, pepsinogen C-producing cells were mucopeptic cells. By 4 weeks after birth, mucous neck cells could be distinguished morphologically. The maturation stages of the chief cells could be traced by electron microscopy along the longitudinal axis of the rat fundic gland by double-staining with anti-pepsinogen C antibody and periodic acid-thiocarbohydrazide-silver proteinate. Positive reactions for pepsinogen C and pepsinogen C mRNA expression were detected in mucous neck cells. Therefore, we conclude that mucous neck cells are precursor cells of chief cells. Mucous neck cells, intermediate cells, and chief cells are in the same differentiating cell lineage.

Alternate activity in the synergistic muscles during prolonged low-level contractions

The purpose of this study was to investigate the functional interrelationship between synergistic muscle activities during low-level fatiguing contractions. Six human subjects performed static and dynamic contractions at an ankle joint angle of 110 degrees plantar flexion and within the range of 90-110 degrees (anatomic position = 90 degrees) under constant load (10% maximal voluntary contraction) for 210 min. Surface electromyogram records from lateral gastrocnemius (LG), medial gastrocnemius (MG), and soleus (Sol) muscles showed high and silent activities alternately in the three muscles and a complementary and alternate activity between muscles in the time course. In the second half of all exercise times, the number of changes in activity increased significantly (P < 0.05) in each muscle. The ratios of active to silent periods of electromyogram activity were significantly higher (P < 0.05) in MG (4.5 +/- 2.2) and Sol (4.3 +/- 2.8) than in the LG (0.4 +/- 0.1), but no significant differences were observed between MG and Sol. These results suggest that the relative activation of synergistic motor pools are not constant during a low-level fatiguing task.

Immunohistochemical detection of activin A, follistatin, and activin receptors during fracture healing in the rat

Activins are multifunctional proteins that belong to the transforming growth factor-beta superfamily and are thought to play an important role in modulating the formation of bone. Activins exert their cellular effects by way of activin type-I and type-II serine/threonine kinase receptors. Follistatin is an activin-binding protein that can suppress the biological effects of activins. In this study, the immunohistochemical expression of activin A, follistatin, and activin receptors was studied during fracture healing in the rat. Activin A was weakly detected in the periosteum near the fracture ends at an early stage but was absent in the chondrocytes around the fracture gap, where endochondral ossification took place. An antibody to follistatin stained osteogenic cells in the periosteum near the fracture ends; moderate and strong staining were observed in proliferating, mature, and hypertrophied chondrocytes at the sites of endochondral ossification. Levels of activin A and follistatin were high near the osteoblasts on the surface of the newly formed trabecular bone. In addition, an intense localization of activin A was noted where multinucleated osteoclast-like cells were present. This study suggests that the activin-follistatin system may contribute to cellular events related to the formation and remodeling of bone during fracture healing. Activin type-I and type-II receptors were co-expressed in intramembranous and endochondral ossification sites. The expression of activin type-I, type-II, and type-IIB receptors in the absence of activin A in the endochondral ossification suggests that other isoforms of activins may signal by way of these receptors.

Sulfated glycosaminoglycans in guinea pig basophils studied by means of cationic colloidal gold

Bone marrow embedding in the hydrophilic resin, Lowicryl K4M, followed by cationic colloidal gold (CCG, pH 1.0) staining was used to study the sulfated glycosaminoglycans (GAGs) and their sites of sulfation ultrastructurally in various maturational stages of both basophil granulocytes and basophil granules in the guinea pig. CCG at pH 1.0 is specific for sulfated GAG staining. Basophil granulocytes and granules reacted positively to CCG with a variety of staining according to the stage of maturation. The formation of basophil granules takes place throughout the myelocyte stage. Early basophil myelocytes contain a large Golgi apparatus with active granulogenesis, while late myelocytes contain a small and less active Golgi apparatus as judged by CCG staining. All the immature granules and some of the granules with characteristic ultrastructure stained positively. However, some of the mature granules had lost their affinity for CCG upon maturation. Interestingly, strongly positive CCG staining was also observed in the trans to transmost Golgi apparatus. This indicates that sulfation of GAGs occurs in the trans to transmost Golgi apparatus in all maturational stages of basophil granulocytes. Treatment with chondroitinase ABC or heparinase I abolished the majority of CCG staining.

Proliferation and migration kinetics of stem cells in the rat fundic gland

The proliferation and migration of stem cells in the developing and adult rat fundic gland have been studied using BrdU immunohistochemistry and BrdU-GSA II (Griffonia-simplicifolia agglutinin-II) double staining. In the developing rat fundic gland, stem cells were first scattered throughout all levels of the epithelia and then concentrated in the depth of the pits. With the elongation and maturation of the fundic glands, stem cells left the gland base and moved upward. By 4 weeks after birth, the development of the fundic gland was completed and stem cells were confined to a narrow proliferative zone in the isthmus, reaching the adult distribution pattern. In the adult rat fundic gland, stem cells in the isthmus differentiated and migrated upward and downward, replacing the surface mucous cells and glandular cells respectively. For upward migration, it took about one week for stem cells to migrate from the isthmus to the surface. For downward migration, it took about two weeks for stem cells to migrate from the isthmus to the neck, and it took 30-36 weeks to reach the gland unit's blind end. Finally stem cells were lost at the deepest level of the glands. The results obtained by simple topographical distribution in the present experiment agreed well with those obtained by quantitative analysis, suggesting the usefulness of BrdU immunohistochemistry for cell kinetic studies.

Cationic colloidal gold staining of acidic glycoconjugates in mouse Paneth cells

The acidic glycoconjugates of mouse ileum Paneth cells were examined with the aid of light and electron microscopy, using cationic colloidal gold (CCG) as a probe. Specimens of mouse ilea were fixed in half-strength Karnovsky's fixative and embedded in Lowicryl K4M resin. Semithin and ultrathin sections were cut of examination with light and electron microscopy, respectively. Examination of the sections using light microscopy revealed the positive staining of CCG at pH 1.0 and pH 2.5, which was detected at the rim of secretory granules and at the supranuclear regions of the Paneth cells. At pH 4.0, in addition to staining of the secretory granule rim, weak staining was observed in the granule core. At pH 7.2, the cytoplasm other than secretory granules exhibited positive CCG staining. Examination of the sections using electron microscopy, at pH 1.0, the trans lamellae of the Golgi apparatus, the rim of the secretory granules, and lysosomes were labeled selectively by CCG. At pH 2.5, labeling was also discernible over the same structures in the cells. However, at this pH, the labeling intensity was stronger than that at pH 1.0, due to the dual labeling of sulfated and sialylated glycoconjugates in these structures. At pH 4.0, the Golgi apparatus, rims and cores of secretory granules and ribosomes were labeled. Lysosomes and nuclei were also positively stained. At pH 7.2, the rims of secretory granules were not stained. The present results indicate that the CCG method gives good resolution and contrast when applied to staining, and therefore is useful for the specific staining of glycoconjugates such as sulfated, sialylated and phosphated glycoconjugates for light and electron microscopy.

Novel method to investigate kinetics of rat skin cells by means of an occlusive dressing method using bromodeoxyuridine

We developed a novel technique to detect S-phase skin cells by applying bromodeoxyuridine (BrdU) epicutaneously using an occlusive dressing (OD) method. BrdU was scarcely absorbed from the skin with a simple epicutaneous application, whereas the incorporation of BrdU was very well promoted with the use of our OD method. We applied BrdU on the backs of rats using this method and investigated the conditions required for an optimal response, with a special focus on the period of application, the concentration of BrdU used and vehicles suitable for the immunocytochemical staining of this agent. From these experiments, we were able to determine that an application time of at least 60 min was necessary to liable S-phase cells, a 2% concentration of BrdU was needed to obtain consistent labeling and aqueous vehicles are satisfactory solvents for BrdU preparations. Epidermal keratinocytes and S-phase cells in the upper portion of dermis were clearly labeled after either intraperitoneal injection of BrdU or after administration by means of the OD method. To ascertain whether this latter method could provide an effective alternative to intraperitoneal injection, we compared the labeling patterns of both methods with respect to the speed of migration of BrdU-labeled basal cells from the basal layer to the horny layer of epidermis. Using either of these two methods, basal keratinocytes were labeled immediately after administration. Three days after the first administration, BrdU-labeled cells were detected in the middle layer of the epidermis, but after 8 days, they were no longer evident in epidermal tissue. As another means of comparing both methods, we used antibody to proliferating cell nuclear antigen (PCNA) and compared the ratio of PCNA-positive basal cells to BrdU-labeled basal cells. The number of PCNA-positive cells was about 4.6 times greater than the number of BrdU-labeled basal cells by both methods. We concluded that the OD method could be used as a substitute for intraperitoneal injection in order to observe cell kinetics using bromodeoxyuridine.

[Lectin histochemistry of the glycoconjugates in conjunctival goblet cells]

The distribution of O- and N-linked glycoconjugates in human conjunctival goblet cells was examined histochemically using biotinylated and fluorescence-labeled lectins simultaneously. Both peanut agglutinin and Erythrina cristagalli agglutinin, specific for O- and N-linked sugar chains, respectively, bound to the same goblet cell, which demonstrated that a conjunctival goblet cell produces and contains both types of glycoconjugates. Maackia amurensis lectin II, specific for sialic acid alpha 2, 3 galactose, bound to the goblet cells, while Sambueus nigra agglutinin, specific for sialic acid alpha 2, 6 galactose, did not. This observation suggested that the terminal galactosyl residue of the glycoconjugates is alpha 2, 3-sialylated in the human conjunctival goblet cells.

Clinicopathologic and prognostic significance of an angiogenic factor, thymidine phosphorylase, in human colorectal carcinoma

BACKGROUND

Platelet-derived endothelial cell growth factor (PD-ECGF) is known to promote the development of new blood vessels, which are fundamental to tumor growth and metastasis. We previously found that thymidine phosphorylase (dThdPase) and PD-ECGF are the same protein.

PURPOSE

We retrospectively examined the expression of dThdPase in primary colorectal carcinomas, its association with angiogenesis and clinicopathologic findings, and its prognostic value.

METHODS

Tissues were obtained from the tumors of 163 patients whose colorectal carcinomas were completely removed by surgery. Microvessels assessed by immunostaining endothelial cells for factor VIII were counted on a 400x field in the most active areas of neovascularization within the tumor. We purified the monoclonal antibody against dThdPase and studied the expression of dThdPase in the same serial sections used for the detection of factor VIII. Those who carried out microvessel counting and dThdPase expression assessment had no knowledge of clinicopathologic findings. The significance of dThdPase in the prognosis of patients with colorectal carcinomas was also examined in the survival analysis of mortality follow-up data covering the period between 1984 through 1991. Reported P values are from two-sided tests of statistical significance.

RESULTS

The mean microvessel count (+/- standard deviation) in dThdPase-positive colorectal carcinoma specimens (17.5 +/- 7.2) was higher (P < .001) than that in dThdPase-negative carcinoma specimens (9.3 +/- 5.5). The dThdPase positivity was in accordance with the microvessel count. dThdPase positivity showed highly significant statistical associations with tumor size, extent of invasion, lymph node metastasis, lymphatic invasion, and venous invasion. Cox regression analysis revealed that dThdPase expression was prognostic for poor disease outcome after adjustment for Dukes' stage and microvessel count.

CONCLUSIONS

These findings suggest that higher levels of dThdPase expression in colorectal carcinomas are associated with more extensive angiogenesis, poor clinical and laboratory findings, and unfavorable clinical outcome.

IMPLICATIONS

Inhibition of dThdPase in human colorectal carcinomas might improve prognosis for some patients.

Ontogeny of proliferative cells in the rat fundic gland

The ontogeny of proliferative cells in the rat fundic gland was studied using bromodeoxyuridine (BrdU) immunohistochemistry from day 17.5 of gestation to 8 weeks after birth. This ontogenic process is divided into 4 stages. (1) The late fetal period extending to 0 day of birth: Proliferative cells were scattered throughout all levels of the stratified epithelium in the earliest stage (day 17.5-18.5 of gestation). With the appearance of a primitive gastric pit at day 19.5 of gestation, proliferative cells were more numerous at the base of the fundic gland. Proliferative cells were concentrated in the gland base and were rarely seen in the epithelial surface from day 21.5 of gestation onwards. (2) One day to 2 weeks after birth: As fundic gland growth proceeded, proliferative cells remained concentrated in the gland base. (3) Two to 4 weeks after birth: Proliferative cells left the gland base and moved upward to reach the adult location in the isthmus. (4) Four to 8 weeks after birth: The development of the fundic gland was complete and proliferative cells remained in a narrow proliferative zone in the isthmus.

Ontogeny of sulphated glycoconjugate-producing cells in the rat fundic gland

The ontogeny of sulphated glycoconjugate-producing cells in the rat fundic gland has been studied using high iron diamine (HID), Alcian Blue (AB) at pH 1.0, high iron diamine in combination with Alcian Blue at pH 2.5 (HID-AB), cationic colloidal gold (CCG) at pH 1.0 under light microscopy and CCG (1.0), HID-thiocarbohydrazide (TCH)-silver proteinate (SP)-physical development (PD) under electron microscopy. From day 19.5 of gestation, sulphated glycoconjugate-producing cells were discernible under both light and electron microscopy. The development of such cells can be classified into four stages: (1) a prenatal period from day 19.5 of gestation extending to 0.5 days after birth; (2) 1 day to 2 weeks after birth; (3) 2 to 4 weeks after birth; and (4) the final period from 4 to 8 weeks after birth. Glycoconjugate-producing cells reached maturity by 4 weeks after birth. Our results indicated that glycoconjugate-producing cells were cells along the wall of foveolar lumen, but not those covering the gastric mucosa surface. Our results also suggested that the trans to transmost Golgi apparatus lamellae were the sites of sulphation in the developing rat stomach.

Enhanced expression of type I receptors for bone morphogenetic proteins during bone formation

Type I receptors for bone morphogenetic proteins (BMPs), i.e., BMPR-IA and BMPR-IB, are transmembrane serine/threonine kinases, that bind osteogenic protein-1 (OP-1, also termed BMP-7) and BMP-4. Using antibodies specific to BMPR-IA and -IB, we have studied the expression of BMP type I receptors in the bone formation process during embryonic development and fracture healing. In the mouse embryo, both BMPR-IA and -IB were expressed in condensing mesenchymal cells at 13.5 days post coitum (p.c.). At 15.5 days p.c., expression of BMPR-IB, but not of BMPR-IA, was observed in the cells in perichondrium of developing cartilage. At 17.5 and 19.5 days p.c., expression of both receptors was observed in chondrocytes and in osteoblasts. In normal rat adult bone, expression of BMPR-IA, but not of BMPR-IB, was observed in osteoblasts in the periosteum. Three days after the femoral fracture, expression of BMPR-IA and -IB was up-regulated in cells at the proliferating osteogenic layer of the periosteum. On day 7, both receptors were found in fibroblast-like spindle cells and chondrocytes in the endochondral ossification sites, and osteoblasts in the newly formed trabecular bone. Expression of BMPR-IA was higher than that BMPR-IB in osteogenic layer on day 3 and in osteoblasts in the trabecular bone on day 7. On day 14, expression of BMP type I receptors was observed at similar sites, albeit with lower expression levels than were observed on day 7. The present data suggest that expression of BMP type I receptors is up-regulated during bone formation, and that they may play important roles in bone morphogenesis.

Expression of decorin mRNA in the skin of patients with ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is an intractable disease developing into severe myelopathy and often accompanied by ossification of several other spinal ligaments and articular ligaments. Therefore, it is highly probable that predisposition to systemic ossification underlies the onset of this disease. Terayama et al(1981) reported that the nuchal skin of OPLL patients tended to be tougher than that of healthy individuals. Decorin is a component of the extracellular matrix which antagonistically regulates the action of Transforming growth factor-beta (TGF-beta). Imamura et al(1995) demonstrated immunohistochemically that decorin increased in the epidermis of the nuchal skin of OPLL patients. This suggests an abnormal expression of the extracellular matrix in the skin of OPLL patients. In the present study, in situ hybridization with non-radioactive synthetic oligodeoxynucleotide probes revealed an enhanced expression of decorin mRNA in the epidermal keratinocytes of OPLL patients. The increased expression of decorin mRNA in the epidermis of OPLL patients may be interpreted as reflecting abnormalities of the matrix associated with ossification of the ligaments. Studies on the role of decorin in ossification will contribute to clarification of the pathophysiology and pathogenesis of OPLL.

Expression of Sia alpha 2-->6Gal beta 1-->4GlcNAc residues on sugar chains of glycoproteins including carcinoembryonic antigens in human colon adenocarcinoma: applications of Trichosanthes japonica agglutinin I for early diagnosis

The N-linked sugar chain structures of the carcinoembryonic antigen (CEA) produced by liver metastases of colon cancers and the normal counterpart of CEA purified from human adult feces (NFA-2) were previously determined comparatively (K. Fukushima, T. Ohkura, M. Kanai, M. Kuroki, Y. Matsuoka, A. Kobata, and K. Yamashita. Glycobiology, 5:105-115, 1995). Seventy-five % of NFA-2 contained complex type sugar chains with Gal beta 1-->3GlcNAc residues, in contrast to the sugar chains of CEA, in which over 90% of the oligosaccharides contained Gal beta 1-->4GlcNAc residues, and Sia alpha 2-->6Gal beta 1-->4GlcNAc residues were detected in 18 to 65% of the oligosaccharides. The expression of Sia alpha 2-->6Gal beta 1-->4GlcNAc residues on CEA molecules in sera and tissues was investigated using Trichosanthes japonica agglutinin I (TJA-I), which interacts with Sia alpha 2-->6Gal beta 1-->4 GlcNAc residues. Ten purified CEA samples bound to a TJA-I column while seven NFA-2 samples passed through the column. Various concentrations of serum CEA samples from patients with metastatic colon cancers exclusively bound to the TJA-I column, reflecting that CEA molecules exfoliated into the blood circulation comprise sugar chains with Sia alpha 2-->6Gal beta 1-->4GlcNAc residues. In histochemical studies involving biotinylated TJA-I, normal mucosa (n = 20) and benign adenomas (n = 20) were not stained, and 83% of well and moderately differentiated colon adenocarcinomas (n = 53) reacted with TJA-I, although poorly differentiated ones (n = 9) and mucinous specimens (n = 10) were negative. Because over 90% of colon adenocarcinomas can be differentiated, TJA-I staining might be applicable to the early diagnosis of colon cancers.

Histopathological study on the effect of octreotide

The present investigation was performed to clarify the mechanism of action of octreotide. On a quantitative study by electron microscopy showed that lysosomes were markedly increased in the patients receiving octreotide. Growth hormone (GH) was shown to be in the secretory granules by the postembedding immunogold technique, but no GH immunostaining was noted of the lysosomes. The present investigation suggests that retention of secretory granules and subsequent lysosomal increase are the mechanism of GH-lowering effect of octreotide.

Pituitary adenylate cyclase activating polypeptide is an extraordinarily potent intra-pancreatic regulator of insulin secretion from islet beta-cells

Insulin secretion from pancreatic islets is controlled by peptides as well as by nutrients. We report here a novel, extraordinarily potent peptidergic regulation of insulin secretion. A 27-residue form of pituitary adenylate cyclase activating polypeptide (PACAP27) as low as 10(-14) to 10(-13) M stimulated insulin release from rat islets in a glucose-dependent manner. PACAP27 also increased cytosolic free Ca2+ concentration ([Ca2+]i) in islet beta-cells. Nitrendipine, a blocker of the L-type Ca2+ channel, abolished both [Ca2+]i and insulin responses. Vasoactive intestinal peptide, a peptide exhibiting 68% amino acid homology with PACAP, also increased [Ca2+]i in beta-cells but only at concentrations in the nanomolar range, indicating that PACAP27 is 4 logs more potent. A 38-residue form of the peptide (PACAP38) stimulated insulin release and increased beta-cell [Ca2+]i in a manner similar to that of PACAP27. PACAP-like immunoreactivity was demonstrated in pancreatic nerve fibers, islets, and capillaries. The results indicate that PACAP is a physiologically occurring peptide in pancreas and that PACAP, in a glucose-dependent manner, activates beta-cells presumably via a high affinity PACAP-selective receptor, raises [Ca2+]i by increasing the activity of L-type Ca2+ channels, and consequently stimulates insulin release. PACAP appears to be by far the most potent insulinotropic peptide known.

[Light and electron microscopic demonstration of acidic glycoconjugates by means of postembedding staining procedures using cationic colloidal gold]

The cytochemical detection of acidic glycoconjugates located in rat gastrointestinal epithelia was performed using tissue sections embedded in Lowicryl K4M and cationic colloidal gold (CCG). CCG was prepared from poly-L-lysine and colloidal gold solution (10 nm). The staining of CCG was amplified after a photochemical silver reaction using silver acetate as an ion donor at the light microscopic level. The staining solutions adjusted to pH 2.5, CCG (2.5) and pH 1.0, CCG (1.0) were used for the characterization of carboxylated and sulfated glycoconjugates. At light microscopic level, CCG (2.5) stained several cell types of mucous cells in the rat gastrointestinal tract, while CCG (1.0) stained selectively mucous cells in gastric pits, glandular pylorus, upper crypts of the proximal colon and entire crypts of the distal colon. At the electron microscopic level, both CCG (2.5) and CCG (1.0) labeled the trans side of the Golgi apparatus and mucous granules in some mucous cells. These results are consistent with previous glycoconjugates histochemistry of the rat gastrointestinal tract at both the light and electron microscopic levels. CCG (2.5) and CCG (1.0) staining methods are useful and reliable postembedding staining procedures for the light and electron microscopic demonstration of intra- and extracellular acidic glycoconjugates.

A case of epidermolysis bullosa hereditaria--dominant dystrophic type of Cockayne and Touraine

We report a patient with the Cockayne and Touraine type epidermolysis bullosa dystrophica domains. A 6-year-old Japanese female developed blisters and erosions on the extremities 3 months after birth. Immunohistology showed a linear binding pattern of the monoclonal antibody against type VII collagen (LH:2) on the epidermal basement membrane. By means of electron microscopy and morphometric analysis, it became apparent that the anchoring fibrils were rudimentary in structure and reduced in number.

Cationic colloidal gold--a probe for light- and electron-microscopic characterization of acidic glycoconjugates using poly-L-lysine gold complex

Cationic colloidal gold (CCG) was used to characterize acidic glycoconjugates in semithin and ultrathin sections of rat large intestine and salivary glands embedded in hydrophilic Lowicryl K4M resin. It was prepared from poly-L-lysine and 10 nm colloidal gold solution. The staining of CCG in semithin sections was amplified after photochemical silver reaction using silver acetate as a silver ion donor and examined under bright-field and epi-illumination microscopy. CCG adjusted to various pH levels was tested on various rat tissues whose histochemical characteristics with regard to acidic glycoconjugates are well known. At pH 2.5 CCG labelled tissues containing sialylated and sulphated acidic glycoconjugates such as the apical cell surface, mucous cells in the distal and proximal colon, and acinar cells of the sublingual gland. In contrast, CCG at pH 1.0 labelled tissues containing sulphated acidic glycoconjugates such as mucous cells in the upper crypt of the proximal colon and mucous cells in the whole crypt of the distal colon. This specificity of CCG was verified by the alteration of CCG staining following several types of cytochemical pretreatment. These results were further confirmed by electron microscopy. CCG staining is thus a useful postembedding procedure for the characterization of acidic glycoconjugates at both the light- and electron-microscopic levels.

Cardiomyopathy, mental retardation, and autophagic vacuolar myopathy. Abnormal MRI findings in the head

A 21-year-old man with childhood-onset mental retardation, non-obstructive hypertrophic cardiomyopathy, and vacuolar myopathy is presented. A histopathological study of biopsied skeletal muscle showed lysosomal glycogen storage mimicking acid maltase deficiency, but biochemical analysis showed normal acid alpha-glucosidase activity. Glycogenosomes were also recognized in endothelial cells on electronmicroscopic examination of biopsied skeletal muscle. Magnetic resonance imaging (MRI) findings in the head revealed the involvement of the central nervous system. This is a new type of lysosomal glycogen storage disease with multisystemic involvement. The specific biochemical defect in this disorder remains to be elucidated.

Subcellular localization of N-acetylglucosaminide beta 1----4 galactosyltransferase revealed by immunoelectron microscopy

We prepared a monoclonal antibody (MAb) against N-acetylglucosaminide beta 1----4 galactosyltransferase purified from F9 embryonal carcinoma cells. The MAb recognized the protein portion of the enzyme, since it inhibited galactosyltransferase activity, reacted with the enzyme both from F9 cells and from bovine milk, and did not exhibit anti-carbohydrate activity. Using this MAb, we studied the subcellular localization of the enzyme by immunoelectron microscopy. Intense staining was observed in trans-Golgi stacks within testicular interstitial cells and mucous neck cells, confirming the specificity of the immunological reaction. Cell surface galactosyltransferase was detected in the following regions: cultured cells such as F9 embryonal carcinoma cells, testicular interstitial cells, seminiferous tubule epithelial cells, Sertoli cells, the head of the epididymal sperm, epididymal epithelial cells, and apical surfaces of epithelial cells in the fundic gland and of intestinal goblet cells. The use of Triton X-100 intensified the cell surface immunoreactivity, and in certain cases the mode of distribution of the cell surface enzyme was different from that described in previous reports. In addition, nuclear envelopes of cultured cells were distinctly stained. The possible significance of the latter finding is discussed in relation to recent advances in nuclear localization of glycoproteins.

Subcompartment sugar residues of gastric surface mucous cells studied with labeled lectins

We examined the intracellular localization of sugar residues of the rat gastric surface mucous cells in relation to the functional polarity of the cell organellae using preembedding method with several lectins. In the surface mucous cells, the nuclear envelope and rough endoplasmic reticulum (rER) and cis cisternae of the Golgi stacks were intensely stained with Maclura pomifera (MPA), which is specific to alpha-Gal and GalNAc residues. In the Golgi apparatus, one or two cis side cisternae were stained with MPA and Dolichos biflorus (DBA) which is specific to terminal alpha-N-acetylgalactosamine residues, while the intermediate lamellae were intensely labeled with Arachis hypogaea (PNA) which is specific to Gal beta 1,3 GalNAc. Cisternae of the trans Golgi region were also stained with MPA, Ricinus communis I (RCA I) which is specific to beta-Gal and Limax flavus (LFA) which is specific to alpha-NeuAc. Immature mucous granules which are contiguous with the trans Golgi lamellae were weakly stained with RCA I, while LFA stained both immature and mature granules. The differences between each lectin's reactivity in the rough endoplasmic reticulum, in each compartment of the Golgi lamellae and in the secretory granules suggest that there are compositional and structural differences between the glycoconjugates in the respective cell organellae, reflecting the various processes of glycosylation in the gastric surface mucous cells.

Ultrastructural immunocytochemical studies of blood group substances in human eccrine glands

We investigated the ultrastructure of blood group antigens A, B, and H in human eccrine glands by means of the immunogold labeling technique. Blood group antigens A, B, and H were found in the Golgi apparatus, secretory granules, and over the apical and basolateral cell membranes of dark cells of eccrine glands depending on the blood group phenotype of the donors. Both A and B antigens were found in the dark cells of AB donors. The labeling pattern of the Golgi stacks seemed to have a polarity whereby the anti-blood group A antibody labeled all the stacks, whereas anti-blood groups B and H bound to the trans side of the Golgi complex. These observations suggest that the blood group substances are secreted into the lumen after being processed through the Golgi apparatus and the immature and mature granules in the dark cells of human eccrine glands.

A retinoic acid responsive gene MK found in the teratocarcinoma system is expressed in spatially and temporally controlled manner during mouse embryogenesis

A newly identified gene MK is transiently expressed in early stages of retinoic acid-induced differentiation of embryonal carcinoma cells (Kadomatsu, K., M. Tomomura, and T. Muramatsu, 1988. Biochem. Biophys. Res. Commun. 151:1312-1318). MK gene has been predicted to code a polypeptide that is rich in basic amino acids and cysteine and is not related to any other peptides so far reported. In the present study, we investigated MK expression during mouse embryogenesis by in situ hybridization. The MK transcript was detected all over the embryo proper of the 7-d embryo, while it was not detectable in the 5-d embryo. The ubiquitous expression continued in the 9-d embryo proper. On the 11th-13th d of gestation, the sites where MK gene was intensely expressed became progressively restricted; these sites were the brain ectoderm around the lens and brain ventricles, the anterior lobe of the pituitary gland, the upper and lower jaw, the caudal sclerotomic half of vertebral column, the limbs, the stomach, and the epithelial tissues of the lung, the pancreas, the small intestine, and the metanephros. These areas include the region where secondary embryonic induction is prominent. In the 15-d embryo, only the kidney expressed MK significantly. These data suggest that MK gene plays a fundamental role in the differentiation of a wide variety of cells; MK gene may also play some specific roles in generation of epithelial tissues, and remodeling of mesoderm.

Nasu-Hakola disease (membranous lipodystrophy). Clinical, histopathological and biochemical studies of three cases

We report 3 cases of Nasu-Hakola disease found in 2 families. These cases had identical clinical features with progressive spastic paraplegia and severe dementia after adolescence. They had no history of any skeletal symptoms, but roentgenographs of their bones presented characteristic evidence of polycystic osteodysplasia. All cases revealed not only manifestations of this condition in the central nervous system, but also peripheral neuropathy with axonal degeneration. The membranous structures in the adipose tissues appeared histochemically to be composed of a kind of compound glycolipid or glycoprotein. Histopathologically, the biopsied rectum showed the infiltration of many histiocytes in the mucosa and ultrastructurally, the granules in these histiocytes showed many membrane-bound vacuoles of different sizes. Interestingly, the histochemical reactivity of the material in the granules was very similar to that of membranous structures in adipose tissues. In the biochemical analysis of lipids in affected adipose tissues, no marked abnormalities were found in the patients. Nasu-Hakola disease is not a typical form of lysosomal storage disease, because lysosomal enzyme activities remain normal and there is no accumulation of urinary oligosaccharides and lipids, no vacuolation of lymphocytes, and no hepatosplenomegaly. However, histochemical findings suggest that the lysosomes may be secondarily involved in this disease, and that the formation of membranous structures might be related to the disturbance of glycolipid or glycoprotein metabolisms.

Glycoconjugate histochemistry of the rat fundic gland using Griffonia simplicifolia agglutinin-II during the development

The development and maturation of fundic glands of Wistar rats were studied using Griffonia simplicifolia agglutinin-II (GSA-II) histochemistry at the light microscopic and electron microscopic levels. In adult rats, mucous neck cells and cells intermediate between mucous neck cells and chief cells were specifically labeled with GSA-II, whereas other fundic gland cells were virtually negative. Ontogenetic studies revealed that GSA-II positive cells appeared at the bottom of the gland by 21 days of gestation. With differentiation and aging, the elongation of the fundic gland continued, and the labeling intensity of the mucous neck cells increased by 3 weeks after birth. Cells intermediate between mucous neck cells and chief cells were discernible from 3 days after birth. Typical mucous neck cells appeared at 3 weeks after birth, when their labeling intensity with colloidal gold (CG) particles approximated that of adults. On the other hand, the reactive cell population gradually moved from the bottom toward the middle portion of the gland. Finally, the reactive cells were localized at the neck portion of the fundic gland. These results suggest that GSA-II is a valuable marker for studying mucous neck cells and both their precursor cells and their derivatives.

Ultrastructural demonstration of Maclura pomifera agglutinin binding sites in the membranocystic lesions of membranous lipodystrophy (Nasu-Hakola disease)

This paper reports three cases of membranous lipodystrophy (Nasu-Hakola disease) in two families and studies the carbohydrate components of membranocystic lesions in all three cases, using twelve kinds of lectins labelled by horseradish peroxidase (HRP). Maclura pomifera agglutinin (MPA), which specifically binds alpha-D-galactose residues, strongly stained typical membranocystic lesions, whereas the other lectins did not. However, Helix pomatia agglutinin (HPA), which specifically binds to N-acetyl-D-galactosamine (GalNAc), stained the membranes of degenerated adipose cells. These were thought to appear during the initial or early stage of the membranocystic lesions. This suggests that a change of carbohydrate residues occurs during the formation of the membranocystic lesions. We also investigated the lectin binding sites at the ultrastructural level using MPA-HRP colloidal gold (CG) conjugate. In the well developed membrane, CG particles were arranged regularly along the minute tubular structures. On the other hand, there were a few irregularly spaced CG particles on the thinner membranes and also on the membranes of the degenerating adipose cells. No CG particles labelled the cell membranes of normal adipose cells. The presence of alpha-D-galactose residues in the membranocystic lesions is demonstrated for the first time at the electron microscopic level.

Purification and properties of N-acetylglucosaminide beta 1----4 galactosyltransferase from embryonal carcinoma cells

N-Acetylglucosaminide beta 1----4 galactosyltransferase was chromatographically purified about 1,700-fold from F9 embryonal carcinoma cells after solubilization with Triton X-100, using N-acetylglucosamine as the acceptor. As the last step of the purification, affinity chromatography was performed either on N-acetylglucosamine-Sepharose or on alpha-lactalbumin-Sepharose: in both cases, two protein bands with molecular weights of around 68,000 and 59,000 were detected by SDS-polyacrylamide gel electrophoresis of the purified preparations. The enzymological properties including behavior toward alpha-lactalbumin were very similar to those of the enzyme from other sources. The specificity of the enzyme was confirmed by determining the structure of the product; it was mostly Gal beta 1----4GlcNAc. beta-Galactosidase-treated embryoglycan (poly-N-acetyllactosamine) and asialo-agalactofetuin could serve as acceptors with the purified enzyme. Thus, the embryonic enzyme, apparently involved in the synthesis of poly-N-acetyllactosamines, has properties similar in several respects to those of the beta-galactosyltransferases so far studied.

Ultrastructural localization of lectin receptors in the monkey retinal photoreceptors and pigment epithelium: application of lectin-gold complexes on thin sections

The cell surface and intracellular binding sites of two lectins, wheat germ agglutinin (WGA) and Ricinus communis agglutinin-1 (RCA-1), in the monkey retina were investigated at the ultrastructural level by means of post-embedding staining of Lowicryl K4M-embedded specimens with lectin-colloidal gold complexes. Effects of pretreatment with neuraminidase were also studied. The techniques enabled us to detect lectin binding sites in the various intracellular compartments of photoreceptor cells, retinal pigment epithelium (RPE), and interphotoreceptor matrices. Wheat germ agglutinin, which recognizes N-acetylglucosamine and sialic-acid residues, showed a prominent and uniform binding to the disc membranes of rod outer segments (ROS), rod connecting cilia, interphotoreceptor matrices, and RPE microvilli. The intensity of these binding sites was markedly reduced when thin sections were pretreated with neuraminidase, except the labeling of ROS disc membranes. Cones were labeled sparsely. The staining of phagosomes in the RPE cytoplasm did not change after neuraminidase digestion. RCA-1, which recognizes galactose residues, revealed a moderate binding to the ROS disc membranes, with a noticeably greater intensity of binding to the basal region of ROS disc membranes. With neuraminidase treatment heavier binding with RCA-1 occurred in interphotoreceptor matrices, connecting cilia and RPE microvilli, whereas there was no significant alteration in binding to the ROS disc membranes. Phagosomes in the RPE were also labeled with this lectin. The results suggest the presence of sialic acid and galactose as the constituent carbohydrates of glycoconjugates in the interphotoreceptor matrices and RPE microvilli.