Isolation and characterization of two polypeptides that form intermediate filaments in bovine esophageal epithelium.

Cells in the stratified squamous epithelium of bovine esophagus contain abundant tonofilaments measuring 6-10 nm in diameter. Two polypeptides, extracted from esophageal epithelium with 0.05 M Tris, pH 7.4, containing 8 M urea and 25 mM beta-mercaptoethanol, comprise 35% of the total extractable protein. These polypeptides have apparent molecular weights of 46,000 and 56,000 daltons and are rich in glutamic acid-glutamine, glycine, and serine. Each polypeptide can be partially purified by DEAE-cellulose chromatography. Mixtures of the purified polypeptides from filaments in vitro that measured 6-10 nm in diameter. Neither polypeptide formed filaments by itself. Filaments formed in vitro give an alpha-keratin type x-ray diffraction pattern.. These data indicate that the tonofilaments in esophageal epithelium are formed primarily from these two polypeptides.

Intermediate filaments in non-neuronal cells of invertebrates: isolation and biochemical characterization of intermediate filaments from the esophageal epithelium of the mollusc Helix pomatia.

To screen invertebrate tissues for the possible expression of intermediate filaments (IFs), immunofluorescence microscopy with the monoclonal antibody anti-IFA known to detect all mammalian IF proteins was used (Pruss, R. M., R. Mirsky, M. C. Raff, R. Thorpe, A. J. Dowding, and B. H. Anderton. 1981. Cell, 27:419-428). In a limited survey, the lower chordate Branchiostoma as well as the invertebrates Arenicola, Lumbricus, Ascaris, and Helix pomatia revealed a positive reaction primarily on epithelia and on nerves, whereas certain other invertebrates appeared negative. To assess the nature of the positive reaction, Helix pomatia was used since a variety of epithelia was strongly stained by anti-IFA. Fixation-extraction procedures were developed that preserve in electron micrographs of esophagus impressive arrays of IFs as tonofilament bundles. Fractionation procedures performed on single cell preparations document large meshworks of long and curvilinear IF by negative stain. These structures can be purified. One- and two-dimensional gels show three components, all of which are recognized by anti-IFA in immunoblotting: 66 kD/pl 6.35, 53 kD/pl 6.05, and 52 kD/pl 5.95. The molar ratio between the larger and more basic polypeptide and the sum of the two more acidic forms is close to 1. After solubilization in 8.5 M urea, in vitro filament reconstitution is induced when urea is removed by dialysis against 2-50 mM Tris buffer at pH 7.8. The reconstituted filaments contain all three polypeptides. The results establish firmly the existence of invertebrate IFs outside neurones and demonstrate that the esophagus of Helix pomatia displays IFs which in line with the epithelial morphology of the tissue could be related to keratin IF of vertebrates.

Expression of simple epithelial type cytokeratins in stratified epithelia as detected by immunolocalization and hybridization in situ.

Multi-layered ("stratified") epithelia differ from one-layered ("simple") polar epithelia by various architectural and functional properties as well as by their cytoskeletal complements, notably a set of cytokeratins characteristic of stratified tissue. The simple epithelial cytokeratins 8 and 18 have so far not been detected in any stratified epithelium. Using specific monoclonal antibodies we have noted, in several but not all samples of stratified epithelia, including esophagus, tongue, exocervix, and vagina, positive immunocytochemical reactions for cytokeratins 8, 18, and 19 which in some regions were selective for the basal cell layer(s) but extended into suprabasal layers in others. In situ hybridization with different probes (riboprobes, synthetic oligonucleotides) for mRNAs of cytokeratin 8 on esophageal epithelium has shown, in extended regions, relatively strong reactivity for cytokeratin 8 mRNA in the basal cell layer. In contrast, probes to cytokeratin 18 have shown much weaker hybridization which, however, was rather evenly spread over basal and suprabasal strata. These results, which emphasize the importance of in situ hybridization in studies of gene expression in complex tissues, show that the genes encoding simple epithelial cytokeratins can be expressed in stratified epithelia. This suggests that continual expression of genes coding for simple epithelial cytokeratins is compatible with the formation of squamous stratified tissues and can occur, at least in basal cell layers, simultaneously with the synthesis of certain stratification-related cytokeratins. We also emphasize differences of expression and immunoreactivity of these cytokeratins between different samples and in different regions of the same stratified epithelium and discuss the results in relation to changes of cytokeratin expression during fetal development of stratified epithelia, in response to environmental factors and during the formation of squamous cell carcinomas.

Glycoconjugate expression in normal, metaplastic, and neoplastic human upper gastrointestinal mucosa.

Glycoconjugate structure in upper gastrointestinal epithelium was studied using five lectins to determine the relationship between aberrant differentiation and glycoconjugate expression. Specimens of normal esophagus, stomach, and duodenum were examined and compared with specimens of columnar metaplasia in the esophagus (Barrett's esophagus) and specimens of adenocarcinoma of the esophagus and stomach. Specific terminal glycoconjugate structures were found for the esophagus, stomach, and duodenum. Minor differences were found between the antral and fundic gland mucosae, reflecting their respective cell populations. In biopsies of Barrett's esophagus, gastric-type columnar metaplasia expressed glycoconjugates indistinguishable from those in the normal stomach. In specialized-type columnar metaplasia, a more restricted expression of glycoconjugates was seen resembling the normal duodenum. The presence of low grade dysplasia in Barrett's esophagus associated with adenocarcinoma had no impact on glycoconjugate expression. However, a distinctive difference in glycosylation was seen in high grade dysplasia of the columnar-lined esophagus and in adenocarcinoma of the esophagus and stomach. Barrett's esophagus is a morphological mosaic in which the glycoconjugate expression resembles that seen in the normal stomach and duodenum. However, in high grade dysplasia and carcinoma, variable deletion of glycoconjugate expression can be found.

Studies on zinc deficiency: changes in trace elements and enzyme activities in tissues of zinc-deficient rats.

Zinc content of testes, bones, esophagus, kidneys, and muscles was decreased, whereas iron content was increased in the testes of zinc-deficient rats compared to restrictedly fed control rats. Histochemical enzyme determinations revealed reduced activities of certain enzymes in the testes, bones, esophagus, and kidneys. In the testes, lactic dehydrogenase (LDH), malic dehydrogenase (MDH), alcohol dehydrogenase (ADH), and NADH diaphorase; in the bones, LDH, MDH, ADH, and alkaline phosphatase; in the esophagus, MDH, ADH, and NADH diaphorase; and in the kidneys, MDH and alkaline phosphatase were decreased in zinc-deficient rats compared to restrictedly fed controls. Succinic dehydrogenase (SDH) revealed no significant changes under the conditions of our experiments in various groups of rats that were investigated. In a "repleted" group of rats, content of zinc in testes and bones increased significantly, compared to the deficient group. The iron content of the testes decreased after repletion with zinc. In the testes, bones, esophagus, and kidneys, the activities of various enzymes increased after repletion with zinc. Inasmuch as the major manifestations of zinc deficiency syndrome in the rat include growth retardation, testicular atrophy, and esophageal parakeratosis, our results suggest that the content of zinc in the above tissues most likely controls the physiological processes through the formation of zinc-dependent enzymes.

Novel protein in human epidermal keratinocytes: regulation of expression during differentiation.

Recently, two groups of cDNA clones have been isolated from human epidermal keratinocytes; the clones correspond to genes whose expression is stimulated by exposure of the cells to UV light or treatment with 4-nitroquinoline 1-oxide or 12-O-tetradecanoylphorbol 13-acetate (T. Kartasova and P. van de Putte, Mol. Cell. Biol. 8:2195-2203, 1988). The proteins predicted by the nucleotide sequence of both groups of cDNAs are small (8 to 10 kilodaltons), are exceptionally rich in proline, glutamine, and cysteine, and contain repeating elements with a common sequence, PK PEPC. These proteins were designated sprI and sprII (small, proline rich). Here we describe the characterization of the sprIa protein, which is encoded by one of the group 1 cDNAs. The expression of this protein during keratinocyte differentiation in vitro and the distribution of the sprIa protein in some human tissues was studied by using a specific rabbit antiserum directed against a synthetic polypeptide corresponding to the 30 amino acids of the C-terminal region of the sprIa gene product. The results indicate that the expression of the sprIa protein is stimulated during keratinocyte differentiation both in vitro and in vivo.

Metabolism of benzo[a]pyrene on the nasal mucosa of Syrian hamsters: comparison to metabolism by other extrahepatic tissues and possible role of nasally produced metabolites in carcinogenesis.

The formation of metabolites of nasally instilled benzo[a]pyrene [(BP) CAS: 50-32-8] was determined. The study was prompted by a report that a high incidence of tumors occurred in tissues of the upper respiratory and alimentary tracts of Syrian hamsters exposed to BP aerosols. The esophagi of anesthetized hamsters were surgically catheterized so that radiolabeled material instilled as BP in the nose could be collected and analyzed for metabolites. About 50% of the instilled BP was metabolized in the nose and, potentially, would have been swallowed in an awake animal. In auxiliary experiments, homogenates of respiratory and alimentary tissues were tested for metabolic activity for BP. The nose, trachea, and lungs had about equally high activities on a per organ basis (5-7 nmol/hr), whereas all other tissues had considerably less activity. The results of the study indicate that nasal metabolism may be important in causing tumors in alimentary as well as upper respiratory tissues.

Covalent DNA damage in tissues of cigarette smokers as determined by 32P-postlabeling assay.

Covalent DNA addition products (adducts) formed by the reaction of chemical carcinogens or their metabolites with DNA are critically involved in the initiation of chemical carcinogenesis and may serve as molecular markers and dosimeters for environmental carcinogen exposures. Using a highly sensitive 32P-postlabeling assay for DNA adduct analysis, we studied DNA damage elicited by cigarette smoke in tissues of smokers. A multitude of characteristic smoking-induced, presumably aromatic DNA adducts were found to occur in a dose- and time-dependent manner in the lung, bronchus, and larynx of smokers with cancer of these organs and to decline only slowly after cessation of smoking. Low levels of adducts appeared to persist for up to 14 years in the lungs of exsmokers with high previous exposures. These results corroborate data of epidemiological studies showing that the lung cancer risk and mortality of smokers increase with the intensity and duration of smoking and decline only slowly after cessation of smoking. Tissue distribution studies in autopsy samples revealed the presence of smoking-associated DNA lesions also in the kidney, bladder, esophagus, heart, ascending aorta, and liver. The most extensive DNA damage was found in lung and heart, i.e., 1 aromatic adduct in about 10(7) DNA nucleotides. Our results suggest that cigarette smoking-induced DNA adduct formation is causally related to cancer in the target organs.

Keratin expression in normal esophageal epithelium and squamous cell carcinoma of the esophagus.

The 8-nm keratin filament is a major component of the cytoskeleton of epithelial cells and epithelial-derived cancers (carcinomas). Recently, it has been shown that the pattern of keratins produced by an esophageal epithelial cell undergoes change upon malignant transformation. In order to evaluate the potential importance of these differences in providing improved diagnostic techniques for pathology, we have investigated the consistency of the patterns of keratins expressed in normal esophageal epithelium, squamous cell carcinoma (SQCC) of the esophagus, and cultured esophageal epithelial cells. In six patients, the keratin pattern expressed by SQCC of the esophagus and corresponding normal esophageal epithelium was consistently different as judged by immunoblot analysis of electrophoretically separated protein extracts. Whereas the SQCCs typically expressed major keratins with molecular weights of 58,000, 56,000, 50,000, and 46,000, the normal esophageal epithelium produced two major keratins with molecular weights of 58,000 and 52,000 and a minor keratin with a molecular weight of 56,000. When normal esophageal epithelial cells were grown in tissue culture, their keratin pattern changed, and keratins with molecular weights of 58,000, 56,000, 52,000, 50,000, 46,000, and 40,000 were expressed. Although some minor variations in keratin patterns were seen, the major differences in keratin pattern expressed by normal esophageal epithelial tissue, SQCC of the esophagus, and cultured esophageal cells were consistent and reproducible.

Activation of c-Ki-ras in human gastrointestinal dysplasias determined by direct sequencing of polymerase chain reaction products.

Activation of c-Ki-ras by point mutation within exon 1 was studied in 33 specimens of dysplastic gastrointestinal lesions or of cancers presumed to arise from dysplasia. Samples were obtained from patients with underlying ulcerative colitis or Barrett's esophagus, two diseases associated with dysplasia and increased rates of colonic or esophageal adenocarcinoma, respectively. Genomic DNA was amplified using primers bounding this exon in the polymerase chain reaction. Polymerase chain reaction products were analyzed by direct dideoxy sequencing. Three point mutations in codon 13 of c-Ki-ras were found, all in colonic specimens (two high-grade dysplasias and one adenocarcinoma arising in ulcerative colitis). No point mutations were observed in the second exon of c-Ki-ras or in and around codons 12, 13, and 61 of c-N-ras and C-Ha-ras in a partial sampling of the specimens. These data indicate that ras family protooncogene activation is an uncommon event at this level of malignant progression in these disease states. Carcinogenesis in ulcerative colitis and Barrett's esophagus may proceed via different pathways than in sporadic colon cancer, perhaps involving loss or inactivation of suppressor genes.

Immunocytochemical evaluation of human esophageal neoplasms and preneoplastic lesions for beta-chorionic gonadotropin, placental lactogen, alpha-fetoprotein, carcinoembryonic antigen, and nonspecific cross-reacting antigen.

Human esophageal neoplasms were studied in comparison to normal, uninvolved, and preneoplastic human esophageal epithelium for the presence of human chorionic gonadotropin (HCG), human placental lactogen (HPL), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and nonspecific cross-reacting antigen (NCA) using the unlabeled antibody peroxidase-antiperoxidase technique. HCG immunoreactivity was identified in 10 of 33 squamous cell carcinomas (33%), in 1 of 6 adenocarcinomas (17%), and 1 of 6 preneoplastic esophageal lesions (17%); while 9 of 33 squamous cell carcinomas (33%) and 1 of 6 adenocarcinomas (17%) contained immunoreactive AFP. Immunoreactive HPL was detected in 6 of 33 squamous cell carcinomas (20%), but in none of the adenocarcinomas. Neither AFP nor HPL immunoreactivity was identified in the 6 hyperplastic lesions which were studied. When stained with an antiserum that was able to detect both CEA and NCA, 27 of 33 squamous cell tumors (82%) and 6 of 6 adenocarcinomas (100%) showed positive immunostaining reactions. Of these, 8 squamous cell carcinomas and 1 adenocarcinoma were subsequently shown to contain only NCA immunoreactivity, while 19 squamous cell carcinomas and 5 adenocarcinomas contained both NCA and CEA immunoreactivity. NCA immunoreactivity alone was identified in 3 of 6 preneoplastic lesions and NCA and CEA immunoreactivity in 1 of 6 preneoplastic lesions. None of the markers was detected in 8 specimens of normal esophageal epithelium which were studied as controls, nor in 6 specimens of uninvolved esophageal epithelium obtained from patients with esophageal cancer. Most tumors expressed 2 or 3 markers, and some tumors were identified which expressed up to 4 of the 5 markers investigated. Only 3 tumors failed to express any of the markers studied. No association was found between the degree of tumor differentiation and presence or absence of HCG immunoreactivity. However, HPL immunoreactivity was more common in poorly differentiated squamous cell carcinomas. In contrast, immunoreactive AFP was more common in well-differentiated squamous cell carcinomas than in other tumor types. Similarly, both CEA and NCA were more frequently expressed in well-differentiated squamous cell carcinomas, adenosquamous carcinomas, and adenocarcinomas than in less differentiated tumors. Our results suggest that HCG, HPL, AFP, CEA, and NCA are tumor-associated antigens in esophageal cancer. Therefore, they could be of value in screening tests for esophageal neoplasms and could be useful in subclassification of esophageal neoplasms.

Distribution and molecular forms of peptides containing somatostatin immunodeterminants in extracts from the entire gastrointestinal tract of man and pig.

Specimens from human porcine mucosal and muscular tissue from the entire gastrointestinal tract were extracted in acid ethanol, subjected to chromatography and analysed for somatostatin-like immunoreactivity by region-specific radioimmunoassays. The concentration of somatostatin-like immunoreactivity from man and pig ranged from 1.13 +/- 0.37 to 101.15 +/- 33.93 pmol/g wet weight, and from 7.64 to 159.48 +/- 23.79 pmol/g wet weight, respectively. In both species the highest concentrations were found in the jejunum. The immunoreactivity in intestinal mucosal extracts was distributed among four major peaks, two of which were identified by HPLC as somatostatin 1-28 and somatostatin 1-14, respectively. A peak of approx. 10 kDa was resolved by ion exchange plus HPLC into three components, two containing at least part of the somatostatin 1-14 sequence as well as (part of) the somatostatin 1-28(1-14) sequence (but differing in charge), the third containing only the 1-28(1-14) sequence. These peptides probably represent uncleaved and partially cleaved prosomatostatin. The fourth component to be identified by gel filtration was slightly larger than somatostatin 1-14. Extracts from the antrum, the pancreas and from muscular tissues contained almost exclusively somatostatin 1-14, and very little somatostatin 1-28, indicating that the somatostatin precursor is processed differently at these sites. Furthermore, extracts of porcine gastric antrum, analysed for somatostatin 1-28(1-14) immunoreactivity, showed two immunoreactive forms in the mucosa and three major forms in the muscular layers.

Somatostatin modulation of neurally mediated pepsinogen secretion from frog esophageal mucosa.

Frog esophageal mucosa contains peptic glands which are innervated by cholinergic neurons. When incubated in a medium containing 1.5 mM CaCl2, pepsinogen release from esophageal mucosa was increased by a high potassium concentration (55 mM KCl), 1,1-dimethyl-4-phenylpiperazinium (DMPP) or bethanechol. Whereas the response to bethanechol remained little changed, the response to high KCl concentrations or DMPP was abolished in the absence of Ca2+. The stimulatory effects of high KCl concentrations and DMPP were also eliminated by the presence of atropine or somatostatin. Furthermore, pepsinogen release in response to bethanechol was dose-dependently inhibited by somatostatin. Frog esophagus was found to contain somatostatin-like immunoreactivity, with a higher density at the end adjacent to the stomach. Chromatography of mucosa extract on Sephadex G-50 revealed a single peak of somatostatin-like immunoreactivity that coeluted with somatostatin-14. Immunohistochemical staining of the mucosa with peroxidase antiperoxidase technique demonstrated the presence of two varieties of somatostatin-like immunoreactivity-containing cells, one individually dispersed within the intercalated septa and the other in groups within the interlobular septa of the peptic glands. These results seem to indicate that somatostatin or somatostatin-like immunoreactivity may play a modulatory role in neurally mediated pepsinogen secretion in the frog esophagus.

Distribution of certain peptide-containing nerve fibres and endocrine cells in the gastrointestinal mucosa in five mammalian species.

The distribution of mucosal nerve fibres containing vasoactive intestinal peptide (VIP), substance P, somatostatin, neuropeptide Y (NPY), and enkephalinlike immunoreactivity was mapped by conventional immunohistochemical techniques throughout the mucosa of the esophagus, stomach, small and large intestines, and gall bladder. In addition, the distributions of endocrine cells immunoreactive for three peptides localized by these antisera (namely somatostatin, pancreatic polypeptide, and substance P) were recorded. Tissues from guinea pigs, rats, dogs, marmosets, and humans were studied. It was hoped that this information would enable possible target tissues and functional roles for the peptides to be identified. In the mucosa, peptide nerve fibres were found throughout the lamina propria, including some which were close to the epithelium and others associated with small blood vessels. Although there was a general similarity of peptide nerve distribution between regions and species, many small variations were observed. VIP and substance P fibres were the most prevalent nerve type; NPY fibres were also usually quite common. The distribution of somatostatin fibres was extremely variable between regions and species, and enkephalin fibres were usually rare. Endocrine cells of open (flask- or pyramid-shaped) and closed (rounded) types were seen; basal cytoplasmic processes (of variable length) were seen on many cells immunoreactive for somatostatin or pancreatic polypeptide. Epithelial cells immunoreactive for substance P were seen in the dog, marmoset, and human. The distributions and shapes of endocrine cells varied widely between areas and species. These studies provide a basis for the correlation of nerve distribution with pharmacological and physiological studies.

Dysplasia in Barrett's esophagus. A clinicopathologic study of six patients.

To evaluate the consequences of dysplasia in Barrett's esophagus, six patients with esophageal mucosal biopsies showing dysplastic Barrett's mucosa in the absence of clinically evident esophageal carcinoma were identified and their clinicopathologic features reviewed. The patients, four men and two women, averaged 60 years and had long histories of gastroesophageal reflux. Four patients had high-grade dysplasia; two had low-grade. Dysplastic Barrett's mucosa appeared to arise most commonly from specialized-type Barrett's mucosa. After a mean follow-up of 29 months, four patients, all with high-grade dysplasia, had esophageal resections. Three of the four were found to have invasive adenocarcinoma, which extended through the esophageal wall in two patients. The fourth patient had a noninvasive adenomatous polyp ("Barrett's adenoma"), an infrequently described form of dysplasia in Barrett's esophagus. The two patients with low-grade dysplasia had developed no clinical indications of carcinoma. The results confirm that dysplastic Barrett's mucosa, particularly the high grade, is a morphologic marker for adenocarcinoma. Biopsy surveillance of patients with Barrett's esophagus is histologically feasible, but prospective studies are required to prove its effectiveness.

Immunohistological localization of alpha 1-microglobulin in normal rat tissues.

The tissue distribution of rat alpha 1-microglobulin (alpha 1-m) was studied by indirect immunofluorescence in various rat tissues using a polyvalent rabbit antiserum to the purified antigen and a monoclonal antibody (H23) to the human homologue, in parallel with a polyclonal anti-rat IgA antiserum. It was found that all tissues stained by anti-IgA were also alpha 1-m positive; these tissues included tissues of the stomach, duodenum, ileum, colon, pancreas, trachea, esophagus and jejunum. However, the observation that IgA plasma cells as well as secretory cells, while positively stained by anti-IgA, are alpha 1-m negative suggests that the association between IgA and alpha 1-m occurs at a postsecretory stage, after the IgA molecules have been transported across the epithelial cells. Additionally, hepatocytes were intensely stained by anti-alpha 1-m antibodies, indicating that the liver, as already suggested by metabolic studies on isolated guinea-pig liver explants, may be responsible for the synthesis of this protein. Among lymphoid tissues, an intense and homogeneous staining was observed in the thymus and the white pulp of the spleen. Sections of lymph nodes, however, showed differential staining; apart from a few isolated dendritic cells in the mantle region of the lymphoid follicles, the germinal centers and medullary cords showed no staining with anti-alpha 1-m antibodies. The paracortical cells, macrophages in the subcapsular sinus, and interfollicular lymphocytes showed intense cytoplasmic staining with anti-alpha 1-m antibodies. In other tissues, macrophages, monocytes, tissue histiocytes, and dendritic cells were alpha 1-m positive. Although they confirm the presence of alpha 1-m in the lymphoid tissues, as already reported in man, these results show that the protein is also present in hepatocytes and in exocrine fluids containing IgA. Since alpha 1-m, like secretory component, can bind to IgA to form stable complexes, these two heavily glycosylated proteins may have similar biologic properties.

Cellular distribution of alpha B-crystallin in non-lenticular tissues.

alpha B-Crystallin is a subunit of alpha-crystallin, a major protein component of the vertebrate lens. Recently, its expression in various extra-lenticular tissues has been demonstrated by both Western and Northern blotting. In this study, the cellular distribution of alpha B-crystallin in rat organs was examined in detail using immunohistochemistry. Positive reactions were observed in lens, iris, heart, skeletal muscle (type 1 and type 2A fibers), striated muscle in skin and esophagus, Henle's loop and medullary collecting duct of the kidney, Schwann cells of peripheral nerves, glia of the central nervous system, and decidual cells of the placenta. A close correlation with markers of oxidative activity suggests that alpha B-crystallin is expressed in cells that have high levels of oxidative function.

Immunohistochemical distribution of hepatic fatty acid-binding protein in rat and human alimentary tract.

Tissues from rat and human alimentary tract were immunostained with rabbit antibodies to fatty acid-binding protein (FABP) isolated from rat liver, since the precise immunohistochemical localization of the protein in gut has not been determined. The results obtained indicated that FABP immunoreactivity was found almost exclusively in intestinal absorptive cells, the sole exception being its presence in the cytoplasm of a few goblet cells. In small bowel, FABP-positive cells were most often found in the upper and middle segments, and less frequently in the lower to terminal portion. Immunoreactive cells were also found in large bowel of rat and human, but with differing patterns of distribution. In rat, positive cells were found mainly in the lower portion of the large intestine, whereas in human positive cells were present in all portions. Immunoreactive cells were detected in rat and human cecum, in the upper half of human rectum, and in human vermiform appendix. No such cells were found in esophageal and nonmetaplastic gastric mucosa or in pancreatic tissue, whereas they were present in great numbers in metaplastic gastric mucosa. The results of this study therefore suggest that FABP is a useful marker for research into the physiology or pathology of absorptive cells in the gastrointestinal tracts of both species.

Isolation and characterization of calcitonin from pericardium and esophagus of eel.

Calcitonin was extracted from the pericardium and esophagus of eel in quantities sufficient to permit purification and chemical characterization. Homogeneous calcitonin could be isolated by a six-step fractionation starting from acetone powder of the organs. The fractionation procedure consisted of acid extraction, gel filtration on Sephadex G-75, chromatography on SP-Sephadex C-25, gel filtration on the Sephadex G-50, chromatography on carboxymethylcellulose, and gel filtration on Sephadex G-50. Fractionation of the hormone was monitored by assay of its biological activity and from its behaviour on thin layer chromatography and polyacrylamide gel disc electrophoresis. The hormone contained 32 amino acid residues, like calcitonins from other species of animals, but its amino acid composition was different from those of previously characterized hormones. Eel calcitonin possessed almost the same, or higher, biological activity as the salmon or chicken hormone, which show the highest specific activity among calcitonins so far isolated.

Unusual histological appearances of barium sulphate--a case report with scanning electron microscopy and energy dispersive x ray analysis.

Multiple birefringent rhomboidal crystals seen on histological examination of a resected oesophagus were subsequently found to contain elemental barium and sulphur on energy dispersive x ray ( EDX ) analysis. Scanning electron microscopy and EDX analysis of readily available commercial barium sulphate suspensions suggested that the two forms of barium sulphate previously described in tissue sections may be a result of the method of preparation of the commercial suspension used. With increased use of barium sulphate prepared by crushing the natural compound, birefringent rhomboidal crystals should be found with increasing frequency in endoscopic biopsy samples and resected specimens.