Hypertrophy of pheochromocytoma cells treated with nerve growth factor and activators of adenylate cyclase

PC12 pheochromocytoma cells treated with nerve growth factor (NGF) in combination with high concentrations of the activators of adenylate cyclase, forskolin or cholera toxin, become more neuron-like in size than cells treated with NGF or with activators of adenylate cyclase alone. Cells treated simultaneously with NGF plus forskolin or cholera toxin paradoxically show less process outgrowth than cells treated with NGF alone. Addition of forskolin or cholera toxin to cells pretreated with NGF, however, produces enlarged cells with intact processes that are indistinguishable from cultured neurons. One possible implication of these findings is that NGF might act in concert with agents that increase intracellular cyclic AMP to cause neuronal maturation during embryogenesis, and that the proper sequence of exposure to these signals is necessary for normal development. Specific activity of acetylcholinesterase is increased by NGF but is unaffected or slightly decreased by forskolin, suggesting that individual aspects of the developing neuronal phenotype are subject to different types of control.

New techniques in gene product analysis

Many of the new technologies that have developed as a result of advances in cellular and molecular biology, genetics, and immunology have had a major impact in clinical medicine and will continue to provide important diagnostic and investigative tools in the future. The ability to localize a wide variety of gene products in tissues has been accomplished largely through the use of immunohistochemistry. Characterization of gene expression at the levels of specific messenger RNAs and genomic DNAs is now possible through the use of both blot and in situ hybridization techniques. These molecular biological technologies provide important new approaches for understanding the pathobiology of disease and for providing more objective and rational diagnostic and prognostic criteria in biopsy specimens. The pathologist is in a unique position to coordinate, implement, and lead efforts utilizing these new methods for the study of human disease. In addition, the pathologist must assume a leadership role in the assessment of the efficacies of the new technologies in resolving specific clinical problems and in providing novel approaches for clinical and basic research.

Localization of thyrotropin-releasing hormone prohormone messenger ribonucleic acid in rat brain in situ hybridization

We studied the distribution of pro- TRH mRNA in rat brain by in situ hybridization histochemistry using radiolabeled single stranded cRNA probes to confirm the hypothesis that the TRH precursor is distributed beyond regions that contain immunoreactive TRH. All regions of the central nervous system previously recognized to contain TRH showed hybridization. Hypophysiotropic neurons in the medial parvocellular division of the paraventricular nucleus showed more intense hybridization than anterior parvocellular division cells, suggesting regional differences in expression. In addition, regions not previously recognized to contain TRH in neuronal perikarya by immunocytochemistry showed specific hybridization for pro-TRH mRNA. These include cells in the olfactory bulbs, dorsal motor nucleus of the vagus, ventrolateral periaqueductal gray, reticular nucleus of the thalamus, and anterior commissural nucleus. Only a single hybridizing band was observed on Northern blots of RNA extracts of the periaqueductal gray and reticular nucleus, identical to that seen in extracts of the paraventricular nucleus. The appearance of pro-TRH mRNA in neurons not previously recognized to contain TRH but which contain the prohormone suggests that non-TRH peptides within the TRH precursor may be preferentially expressed in certain regions of the brain.

Medullary thyroid carcinoma in the Syrian golden hamster: an immunohistochemical study

Spontaneously occurring thyroid neoplasms exhibiting solid and/or anaplastic growth patterns in the Syrian golden hamster have been thought to be derived from follicular cells. Eight neoplasms of this type have been analyzed immunohistochemically and have been classified as medullary thyroid carcinomas (MTC) on the basis of their content of calcitonin (CT). Well differentiated MTCs in this species were composed of polyhedral cells showing uniform CT immunoreactivity while the poorly differentiated MTCs most often had spindle patterns of growth with marked variation in CT immunoreactivity. Both well and poorly differentiated MTCs contained entrapped follicles which were CT negative. In contrast to MTC in the rat and in humans with familial MTC, the tumors in hamsters were not associated with C-cell hyperplasia. The Syrian golden hamster may, therefore, serve as a useful model to study the factors which are responsible for the development of spontaneous (non-familial) MTC.

Hyperplastic lesions of the gastrointestinal endocrine cells

A substantial body of knowledge is presently available on the morphologic, histochemical, ultrastructural, and functional characteristics of both the normal endocrine cell population of the gut and their related endocrine tumors. In contrast to this, we have only recently begun to recognize the existence of hyperplastic proliferations of various endocrine cell types, and information is therefore steadily accumulating on the morphologic criteria for their recognition, their clinicopathologic correlates and the clinical relevance of this morphologic finding. Hyperplastic proliferations of various endocrine cell types most often develop as a secondary phenomenon in a variety of clinical situations, and may modify the clinical course of the associated condition in a manner that underscores the functional interrelationships these endocrine cells have not only with each other but with other cell types as well. However, similar proliferations may also occur as a primary event (e.g. primary antral G-cell hyperplasia) and give rise to clinical and biochemical features attributable to the overproduction of their specific hormonal product (e.g. Zollinger-Ellison Syndrome, type I). This communication provides a broad overview of the current state of our knowledge of hyperplastic lesions of a variety of gut endocrine cell types in humans, their pathophysiologic significance, their relationship (if any) to the subsequent development of endocrine tumors (i.e. the hyperplasia-neoplasia sequence), and the utility of certain experimental models for the study of such proliferations in a variety of animal species.

A prospective trial of colchicine for primary biliary cirrhosis

We entered 60 patients with primary biliary cirrhosis in a double-blind randomized controlled trial to determine whether colchicine is therapeutically effective. Thirty patients had early disease (Stages 1 and 2), and 30 had advanced disease (Stages 3 and 4). Fifteen patients with early disease and 15 with advanced disease received colchicine (0.6 mg twice daily), and the remainder received placebo. Patients were studied about every two months; those remaining in the blind phase at two years underwent repeat liver biopsy and were then placed on open-label colchicine (0.6 mg twice daily). With a few exceptions, the results in patients with early disease were similar to those in patients with advanced disease; hence, data on patients in all stages were combined in the main analysis. During the two-year study period the colchicine-treated patients, as compared with the placebo-treated patients, had improvement in levels of serum albumin, serum bilirubin, alkaline phosphatase, cholesterol, and aminotransferases. However, there was no such improvement in the severity of symptoms or physical findings; moreover, there was no significant difference in the histologic changes noted at liver biopsy in the two treatment groups. At four years after entry, the cumulative mortality from liver disease was 21 percent in patients given colchicine and 47 percent in those given placebo (P = 0.05). The only side effect of colchicine was diarrhea, noted in three patients. The consistent and significant improvement in a number of markers of liver disease and the apparent decreased mortality from liver disease suggest that colchicine may provide some long-term clinical benefit in patients with primary biliary cirrhosis. However, the failure of colchicine to reduce hepatic inflammation and fibrosis leaves uncertain the effect of the drug on the longterm outcome of this disease.

In situ hybridization methods for the detection of somatostatin mRNA in tissue sections using antisense RNA probes

In situ hybridization studies with [32P] and [3H] labelled antisense RNA probes were undertaken to determine optimal methods of tissue fixation, tissue sectioning, and conditions of hybridization, and to compare the relative merits of the two different radioactive labels. The distribution of somatostatin mRNA in neurons of rat brain using a labelled antisense somatostatin RNA probe was employed as a model for these studies. The highest degree of sensitivity for in situ hybridization was obtained using paraformaldehyde fixation and vibratome sectioning. Optimal autoradiographic localization of mRNA was obtained within 7 days using [32P] labelled probes. However, due to the high energy emittance of [32P], precise intracellular localization of hybridization sites was not possible. [3H] labelled RNA probes gave more precise cellular localization but required an average of 18-20 days autoradiographic exposure. The addition of the scintillator, PPO, decreased the exposure time for the localization of [3H] labelled probes to seven days. We also report a method for combined in situ hybridization and immunocytochemistry for the simultaneous localization of somatostatin in mRNA and peptide in individual neurons.

Lymphatic and blood vessel invasion in breast carcinoma: a useful prognostic indicator?

Recent studies have presented compelling evidence to support the prognostic importance of peritumoral lymphatic and blood vessel invasion in breast cancer. This parameter appears to be particularly valuable in the hands of pathologists who are experienced in diseases of the breast and who have developed standardized criteria and expertise in their recognition. However, its application is seriously hampered by various factors, especially interobserver and intraobserver differences in interpretation. A more uniform and objective approach, such as the use of immunohistochemical techniques, may be helpful in overcoming these obstacles. This may render lymphatic and blood vessel invasion a reliably reproducible indicator that a practicing pathologist can utilize to recognize high-risk patients and recommend appropriate therapy. The extension of this approach to evaluate neoplasms of other organs--such as malignant melanomas and thyroid, uterine, and cervical carcinomas--should also be explored.

Anti-lymphocyte antibody Leu-7 (HNK-1) recognizes a constituent of neuroendocrine granule matrix

Anti-lymphocyte monoclonal antibody HNK-1 (Leu-7) reacts with the cell surfaces of natural killer (NK) lymphocytes and with myelin-associated glycoprotein (MAG). This antibody reacts intensely with normal and neoplastic adrenal medullary cells. A small proportion of normal pancreatic islet cells, anterior pituitary, and gastroenteropancreatic endocrine cells also show Leu-7 immunoreactivity. In adrenal medulla, ultrastructural immunocytochemical studies and immunoblot analyses reveal that Leu-7 reacts with an intracellular protein of MW 75 KD which is localized within the matrices of the chromaffin granules. The MW of this protein differs from those of MAG and chromogranin A. The findings suggest that Leu-7 immunoreactivity might be a new marker for specific subsets of secretory granules.

Argyrophil cells in Brenner tumors: histochemical and immunohistochemical analysis

Argyrophil cells were identified by the single-impregnation Grimelius technique in 11 of 28 (39%) Brenner tumors, accounting for less than 1% of the tumor cell population in all the cases. All tumors with argyrophil cells were stained to demonstrate calcitonin, somatostatin, gastrin, adrenocorticotropic hormone, neurotensin, insulin, glucagon, and serotonin; and four of them (three benign and one borderline) were also stained for chromogranins with the monoclonal antibody LK2H10. Serotonin was present in nine of the 11 cases with argyrophil cells. Neurotensin and somatostatin were found in one borderline tumor, which also contained serotonin. Chromogranin reactivity was demonstrated in all four cases in which it was examined. Ultrastructural examination of one tumor revealed that the argyrophil cells contained secretory granules, 80 nm in diameter, and had elongated cytoplasmic processes that extended between the more numerous nonargyrophil tumor cells. The argyrophil cells of Brenner tumors are similar to those of urothelium in the frequency with which they are immunoreactive for serotonin and the rarity with which they are reactive for peptide hormones. These cells differ from those of mucinous ovarian tumors, which often contain both serotonin and peptide hormones. The findings of this study lend additional support to the close similarity of the epithelial components of Brenner tumors and urothelium.

Intramammary lymphatic invasion in breast carcinomas. Evaluation using ABH isoantigens as endothelial markers

Recent studies indicate that intramammary lymphatic invasion represents an important prognostic parameter in breast carcinomas. However, the identification of intramammary lymphatic invasion in tissue sections is a subjective procedure, frequently hampered by factors such as fixation artefacts and interobserver variations. In this study, monoclonal antibodies to ABH isoantigens were applied on formalin-fixed, paraffin-embedded breast carcinoma tissue by using the avidin-biotin-peroxidase complex technique. In addition, the H antigen was localized using the Ulex europeus agglutinin I lectin binding technique. Isoantigen localization provided excellent delineation of lymphatics and blood vessels, in general unhampered by the retention of isoantigen expression in some breast carcinomas. In comparison, Factor VIII-related antigen localization required prior trypsin enhancement and was less sensitive and less consistent. The staining for isoantigens was more intense in vascular than in lymphatic endothelium. ABH isoantigen localization of lymphatic channels identified lymphatic tumor emboli peripheral to and within the carcinomas, and distinguished bona fide intramammary lymphatic invasion from tissue shrinkage artefacts. The applicability to routinely processed tissue permits retrospective studies and renders the identification of intramammary lymphatic invasion a more objective procedure. Further studies are needed to assess the role of this technique in evaluating the prognostic value of intramammary lymphatic invasion; the technique may be extended also to the study of other neoplasms.

Establishment of a continuous somatostatin-producing line of medullary thyroid carcinoma cells from BALB/c mice

A continuous line of somatostatin-producing medullary thyroid carcinoma cells was established from a transplantable tumour in BALB/c mice. Virtually all of the somatostatin immunoreactivity co-chromatographed with somatostatin 14. The tumour cells replicated in spinner cultures with a doubling time of approximately 4 days, and the concentration of somatostatin released into the culture medium increased in proportion to the number of cells. Two- to threefold increases in amounts of stored and released somatostatin were observed after treatment of the cells with bromodeoxyuridine. This cell line might be valuable for studies of somatostatin regulation in normal and neoplastic C-cells, and for other studies of C-cell biology which require a mouse model.

Immunocytochemical demonstration of growth hormone-releasing factor in gastrointestinal and pancreatic endocrine tumors

Growth hormone-releasing factor (GRF), a linear peptide that exists in a number of different molecular forms (GRF-44, -40, -37, and-31) has been shown to be responsible for the acromegaly associated with certain endocrine tumors of the pancreas and other foregut-derived structures. With the use of two anti-sera (#1A850 and G59/901) directed against different segments of the GRF molecule, a series of 24 pancreatic and 35 gastrointestinal endocrine tumors, not associated with acromegaly, were surveyed systematically for immunocytochemical localization of GRF in the tumor cells. Strong immunoreactivity for GRF was encountered in 10 tumors (6 pancreatic and 4 gastrointestinal). While all ten tumors were immunoreactive against G59/901, which recognizes GRF-44, -40, and -37, two jejunal carcinoids showed additional immunostaining with 1A850 that is specific for GRF-44. Seven of these ten tumors were also immunoreactive for a variety of other regulatory peptides and neurotransmitters, including gastrin, insulin, glucagon, serotonin, substance P, somatostatin, pancreatic polypeptide, vasoactive intestinal peptide (VIP), and adrenocorticotropic hormone (ACTH). No consistent pattern of association between GRF and the other regulatory substances was evident. These findings indicate that, even in the absence of associated acromegaly, up to 17% of endocrine tumors of the gastro-entero-pancreatic (GEP) axis show immunoreactivity for GRF and that such reactivity is associated more frequently with pancreatic (25%) than with gastrointestinal (11%) endocrine tumors.

Tumor marker expression in breast carcinomas and relationship to prognosis. An immunohistochemical study

A collaborative immunohistochemical study was carried out to examine the expression and prognostic significance of tumor markers in a retrospective series of 233 invasive breast carcinomas. The patterns of tumor marker expression in 94 patients with short remission duration (recurrence within five years) were compared with 50 patients with intermediate (at five to ten years) and 89 patients with long (no recurrence at ten years or longer) remission durations. The antigens examined were carcinoembryonic antigen (CEA), human chorionic gonadotropin (HCG), placental lactogen, alpha-lactalbumin, and pregnancy-specific beta-1 glycoprotein. Carcino-embryonic antigen was the most frequently expressed antigen, whereas HCG was demonstrated least frequently. Also, the ABH isoantigen status was examined using monoclonal antibodies; isoantigen expression was observed in a subset of breast carcinomas, contrary to previous reports of total deletion in breast cancer. Two of the markers, CEA and HCG, were examined by both laboratories, each with two different antisera and also with both PAP and ABC immunohistochemical technics. Meticulous efforts were taken to provide quality control and ensure reproducibility of results. These included the use of serial sections of duplicate pathologic material by both institutions, standardization of experimental conditions and interpretation criteria, double-blind evaluation of exchanged slides, and use of standardized data sheets to record staining extent and intensity. No significant disagreements were observed between data obtained through the different approaches. The steps that were taken to minimize interobserver and interinstitutional differences in this study are presented as a model for collaborative immunohistochemical studies. The expression of tumor markers, alone or in combination, was not found to bear any significant relationship to prognostic indicators, such as the likelihood of recurrence, interval before recurrence, or presence of metastasis.

Spontaneous proliferative lesions of the adrenal medulla in aging Long-Evans rats. Comparison to PC12 cells, small granule-containing cells, and human adrenal medullary hyperplasia

Aging rats of the Long-Evans strain spontaneously develop diffuse and nodular hyperplasia of the adrenal medulla in association with other abnormalities commonly encountered in human multiple endocrine neoplasia syndromes. The cells which comprise the adrenal nodules resemble those in the parent tumor of the rat PC12 pheochromocytoma cell line in that they show varying degrees of spontaneous or nerve growth factor-induced neurite outgrowth in culture and they contain little or no epinephrine. In addition, cells from at least some of the nodules contain immunoreactive neurotensin and neuropeptide-Y, which are also found in PC12 cells. There are a number of striking resemblances between the cells in adrenal nodules and the small granule-containing cells in the normal rodent adrenal. The findings suggest that spontaneous rat adrenal medullary nodules and PC12 cells might be derived from small granule-containing cells, or that cells within the nodules might regain properties of immature chromaffin cells and acquire characteristics of small granule-containing cells and of PC12 cells in the course of neoplastic progression. They further suggest a possible relationship between proliferative capacity and neurotransmitter phenotype in the adult rat adrenal medulla. By virtue of their sparse epinephrine content and their small granules, the cells in adrenal medullary nodules of Long-Evans rats differ from those in adrenal medullary nodules of humans with multiple endocrine neoplasia syndromes.

ABH blood group isoantigen expression in breast carcinomas--an immunohistochemical evaluation using monoclonal antibodies

The ABH blood group isoantigen status of a retrospective series of 233 invasive breast carcinomas was examined, employing monoclonal antibodies (MCAB) against A, B, and H antigens with the avidin-biotin-peroxidase complex method. In addition, the H antigen was localized with Ulex Europeus Agglutinin I (UEAI) binding. The MCABs provided consistent and specific staining of erythrocytes and endothelium, as well as normal and neoplastic breast epithelium. The anti-H MCAB yielded cleaner background and less intense staining, but otherwise the staining distribution was comparable to the UEA I technique. Contrary to previous reports, deletion of isoantigen expression was not universal in all invasive carcinomas. Whereas 64%, 77%, and 73% of carcinomas from groups A, B, and AB patients, respectively, demonstrated total isoantigen loss, the remaining tumors exhibited variable degrees of isoantigen expression. Moreover, those carcinomas with complete loss of A and B determinants still displayed variable degrees of H immunoreactivity. Carcinomas from group O patients had different degrees of H antigen deletion, with only 12% showing total loss. Statistical analysis revealed that the isoantigen status bore no significant relationship to various epidemiologic, clinical, and pathologic parameters and did not serve as a useful prognostic determinant.

Nerve growth factor may function as a survival factor for human neuroblastoma cells in culture

Cells from two human neuroblastomas were found to exhibit a marked dependency on nerve growth factor (NGF) for survival in primary cultures. Cells from both tumors also responded to NGF by forming processes, but survival was not necessarily associated with process outgrowth. Lines of replicating cells could not be obtained from either tumor. NGF-dependent survival has not previously been reported as a characteristic of NGF-responsive human neuroblastoma cells in primary cultures or in cultures of established cell lines. Our findings suggest that tumors which require NGF for survival might constitute a biologically distinctive subset of neuroblastomas, or that NGF might function as a survival factor for some human neuroblastomas only in suboptimal or deleterious environments.

G-cell hyperplasia in chronic hypercalcemia. An immunocytochemical and morphometric analysis

The distribution of antropyloric G cells was mapped immunocytochemically and quantitated morphometrically in chronically hypercalcemic and normocalcemic patients. In the normocalcemic (control) patients, the G-cells were sparse in number and confined to the lower third of the antropyloric mucosa, where they were distributed singly or in small clusters within the glands. The absolute G cell (AGC) counts were 5.8 +/- 0.26 (mean +/- SE) per 0.25 sq mm of mucosa. The hypercalcemic patients showed a marked increase in their antropyloric G-cell population. The cells were uniformly distributed throughout the lower two-thirds of the mucosal thickness and were present in large numbers in practically every gland. The AGC counts in these hypercalcemic patients were 48.2 +/- 13.0, a statistically significant increase. These observations indicate that in man chronic hypercalcemia of diverse etiology is associated with antropyloric G-cell hyperplasia. The physiologic significance of this finding and its role in the pathogenesis of peptic ulcer disease needs to be elucidated.

Multidirectional differentiation in neuroendocrine neoplasms

Histopathological and experimental observations indicate that tumors composed wholly or in part of neuroendocrine elements may arise in tissues derived from ectoderm (including neuroectoderm), mesoderm, and endoderm. These tumors frequently exhibit multidirectional differentiation as manifested by multihormonality and by the presence of morphological features indicative of divergent differentiation both in vivo and in vitro. The existence of stem cells, plasticity of differentiated cells, microenvironmental influences, and random events are factors which might all interact to determine the characteristics of any particular tumor. The production of characteristic regulatory peptide products in association with tumors of specific histological subtypes and with other neuroendocrine markers suggests mechanisms for nonrandom activation of multiple genes common to neuroendocrine-programmed cells. Future studies applying new molecular biological techniques to intact tissues and to in vitro models may help to clarify the mechanisms that regulate the expression of the neuroendocrine phenotype in normal and neoplastic states.

Endometrial carcinoma with argyrophil cells: a histochemical and immunohistochemical analysis

Fourteen of fifty-three cases of endometrial carcinoma (26 per cent) contained varying, usually small numbers of argyrophil cells, as demonstrated by Grimelius silver nitrate staining of formalin-fixed paraffin-embedded sections. In eight cases the argyrophilia was present in the apical region of glandular cells (type 1 cells) or throughout the cytoplasm of glandular or squamous cells (type 2 cells). The distribution of argyrophilia in these cells closely paralleled that of mucin or glycogen, and pretreatment of the sections with disease resulted in a loss of argyrophilia in the glycogen-rich tumors. In six cases individual round, ovoid, and flask-shaped argyrophilic cells were present also within the glandular epithelium (type 3 cells). In all six cases, similarly distributed cells were positive immunohistochemically for serotonin. Immunohistochemical staining for a battery of polypeptide hormones (calcitonin, gastrin, somatostatin, adrenocorticotropin [ACTH], and neurotensin) revealed positive staining for ACTH in one of the six tumors that contained type 3 cells and positive staining for somatostatin in another. Ultrastructural examination of the ACTH- and serotonin-positive tumor disclosed cells with granules 80 nm in diameter. Types 1 and 2 argyrophil cells were found in small numbers in several specimens of normal proliferative and secretory endometrium, but type 3 argyrophil cells were not identified in these specimens. Although focal argyrophilia is a frequent feature of endometrial carcinomas (26 per cent), the presence of type 3 argyrophil cells containing hormones, as evidenced by the immunohistochemical demonstration of serotonin and occasionally polypeptide hormones, is much less common (11 per cent).

Thyroglobulin and calcitonin immunoreactivity in canine thyroid carcinomas

Although thyroid gland neoplasms are well-recognized entities in dogs, the diagnosis and classification of these tumors often is difficult. In contrast to human thyroid carcinomas, which are predominantly of the papillary or follicular types, a relatively high proportion of the canine tumors contain compact cellular areas and resemble, to some extent, medullary thyroid carcinomas. In order to assess the value of immunohistochemical techniques in the identification and classification of these neoplasms, 21 canine thyroid carcinomas were examined for the presence of thyroglobulin and calcitonin using the peroxidase-antiperoxidase technique. Four major patterns of thyroglobulin immunoreactivity were present in the tumors, including diffuse cytoplasmic positive reaction, apical staining in the cells bordering the neoplastic follicular lumens, intracytoplasmic droplet staining, and staining of intrafollicular colloid. All follicular and mixed compact cellular/follicular tumors contained immunoreactive hormone, while only four of six compact cellular carcinomas were thyroglobulin-positive. The extent of thyroglobulin reactivity was consistently greater in tumors of the follicular and mixed patterns than in carcinomas of the purely compact cellular type. Two of four metastases, each of which retained the mixed pattern of the primary tumors, were thyroglobulin-positive. No medullary thyroid carcinomas were identified, but scattered calcitonin-positive cells in one mixed and in one compact cellular tumor were interpreted as entrapped nonneoplastic C cells. Immunohistochemical localization of thyroglobulin should facilitate the diagnosis of canine tumors of suspected thyroid follicular cell origin, particularly those arising in ectopic sites (i.e., heart base) and those presenting as metastases.

Alpha-lactalbumin as an immunohistochemical marker for metastatic breast carcinomas

Alpha-lactalbumin (ALA), a milk protein, was demonstrated by immunohistochemistry with polyclonal antisera from three different sources in primary and metastatic breast carcinomas, and mammary Paget's disease. ALA localization was observed in 67% of mammary carcinomas, and in 62% of their metastases to sites which included lymph nodes, lung, bone, liver, pericardium, skin, and subcutaneous tissue. There was close correlation between primary and metastatic breast carcinomas in ALA positivity, but no correlation between ALA positivity and histologic differentiation. A variety of nonmammary neoplasms were examined for ALA immunoreactivity. In contrast to ALA immunoreactivity of breast tissue, which was removed by preabsorption of antiserum with ALA antigen, a number of skin appendage tumors, salivary gland tumors, and mesotheliomas demonstrated positive staining which was not abolished by preabsorption and was most likely due to the presence of cross-reacting antibodies. One commercial ALA antiserum also reacted with pancreatic islet cells in a distribution similar to glucagon. Our results demonstrate the presence of ALA in breast carcinomas and its potential value to the surgical pathologist in the workup of metastatic carcinomas of unknown primary sites. However, the staining encountered in some nonmammary tumors necessitates caution in its interpretation.

Psammomatous somatostatinomas of the duodenum

The presence of psammoma bodies in carcinoid tumors of the gastrointestinal tract is a rare occurrence; it has also been reported to be associated with features of somatostatin production by the tumor cells. The morphologic features of three such tumors arising in the duodenum were studied by a combination of histochemical, immunocytochemical, and ultrastructural techniques in an effort to delineate their secretory profile and further subclassify them. All tumors showed a mixed architectural pattern with prominent areas of glandular differentiation. The psammoma bodies were almost exclusively located within the glandular lumina. In each instance, the majority of tumor cells showed histochemical and immunocytochemical features of somatostatin-containing cells, and one tumor studied ultrastructurally showed numerous large- and small-sized intracytoplasmic secretory granules, both of which contained somatostatin. In contrast to other endocrine tumors of the duodenum that frequently have a multihormonal secretory profile, psammomatous duodenal carcinoids are associated with the exclusive presence of somatostatin within tumor cells. While many more of such examples of this uncommon tumor need to be systematically investigated for their immunocytochemical and ultrastructural characteristics, duodenal somatostatinomas need to be included in the differential diagnosis of psammomatous tumors.

Clonal strains of rat medullary thyroid carcinoma cells that produce neurotensin and calcitonin. Functional and morphologic studies

Strains of rat medullary thyroid carcinoma cells were established by two different techniques which were designed to ensure that clonal populations originated from single cells. The clonal strains (44-3C1 and 6-23C6) secreted both immunoreactive calcitonin (CT) and neurotensin (NT) and had growth characteristics that were similar to those of the parent cell lines. Both the 44-3C1 strain and the parent 44-2 cell line consistently produced more CT and NT than the 6-23C6 clonal strain or the parent 6-23 cell line. Peptide secretion in these clonal strains was stimulated by calcium and norepinephrine. Both clonal strains, similar to the parent lines, produced 4 to 12 times more NT than CT. Immunohistochemical studies showed that all cells in both clonal strains stained positively for CT. NT was also present in all cells from both strains with approximately 2% of the cells showing intense staining for this peptide. Ultrastructurally, the cells contained membrane-bound secretory granules which had a mean diameter of 95 nm. Secretory granules were relatively numerous in only 2% of the cells where they tended to be concentrated in cell processes. These studies demonstrate that single rat medullary thyroid carcinoma cells produce both CT and NT and that these strains are useful models for studies of NT and CT biosynthesis and for investigations of the regulation of secretion of two peptides from a single cell type.