Ultrastructural and morphometric studies related to expression of the cell adhesion molecule PECAM-1/CD31 in developing rat lung

It has recently been postulated that platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) might play a role in vascular tube formation. To evaluate the role of PECAM-1/CD31 in the formation of the capillary network in vivo, we conducted an ultrastructural immunohistochemical evaluation of the localization of PECAM-1/CD31 and its developmentally regulated expression in the periphery of the lungs of fetal, newborn, and adult rats. PECAM-1/CD31 was present mainly on luminal surfaces and at the junctions between endothelial cells. Moreover, in fetal lung, products of the immunoreaction were also found on the abluminal surfaces of endothelial cells. To relate those findings to the developmental changes in the capillary area of the lung, we performed a morphometric study of electronmicrographs. The cross-sectional area of blood vessels at the periphery of the lungs was significantly greater in 15-19-day-old fetuses than in postpartum animals (p<0.0001). Disappearance of the expression of PECAM-1/CD31 on the abluminal endothelial surface paralleled the changes in the cross-sectional area of blood vessels that occurred during the perinatal period. (J Histochem Cytochem 48:1283-1289, 2000)

[Clinical studies of azithromycin, a new macrolide antibiotic, for infections in the field of surgery]

The efficacy of a newly developed macrolide antibiotic, azithromycin, for infections in the field of surgery, was investigated clinically by means of collaborative studies conducted in 17 major institutes and their affiliated hospitals throughout Japan. The following results were obtained. Clinical assessment: Azithromycin was administered at a dose of 250 mg or 500 mg once a day for 3 days. Clinical efficacy was evaluated in 170 patients. These subjects consisted of 81 with superficial purulent diseases, 12 with mastitis, 25 with periproctal abscess, 42 with superficial secondary infection due to trauma, burn and operative wound, 5 with cholecystitis or cholangitis, and 5 with other infections. The clinical efficacy rate was 96.3% (78/81) for superficial purulent diseases, 83.3% (10/12) for mastitis, 84.0%(21/25) for periproctal abscess, and 76.2%(32/42) for superficial secondary infection due to trauma, burn and operative wound. The overall clinical efficacy rate was 88.8%(151/170) respectively. The bacteriological eradication rate was 87.9%(116/132) for gram-positive bacteria, 85.0%(34/40) for gram-negative bacteria, and 100%(63/63) for anaerobic strains of casual bacteria, which were isolated from 140 patients. The overall bacteriological eradication rate was 90.6%(213/235) respectively. Adverse effects were observed in 6 of 170 patients in whom they were evaluated. They consisted of gastrointestinal symptoms in 5 patients and exanthema in 1. Abnormal changes in clinical laboratory test values were observed in 5 patients, and consisted of eosinophilia in 1, elevations of S-GOT and S-GPT in 1, elevations of S-GOT, S-GPT and gamma-GTP in 1, elevation of S-GPT in 1, and elevations of AL-P and gamma-GTP in 1. These results suggest that azithromycin is very useful for surgical infections in the field of surgery.

A case of orbital lymphoproliferative lesion diagnosed as malignant lymphoma after recurring 11 years later

Background: Most primary lymphoproliferative lesions in the ocular adnexa, including the eyelid, conjunctiva, and orbit, are diagnosed as low-grade malignant lymphomas. Recurrence and dissemination of these tumors are rare in Japan. The long-term prognosis for this disorder still remains to be clarified.Case and Method: A 53-year-old woman was first referred to us for right orbital tumor in 1986. After subtotal resection of the tumor, the patient received no additional treatment. She visited us in 1997 with the complaint of bilateral orbital tumor. Biopsied specimens were examined histologically using hematoxylin-eosin and immunohistological staining. Southern blot hybridization was used to detect immunoglobulin gene rearrangement. The paraffin-embedded specimen obtained in 1986 was also examined for immunoglobulin gene rearrangement using nested polymerase chain reaction technique. Findings: The specimens from 1997 and 1986 were both diagnosed as lymphoid type of inflammatory pseudotumor, based on polyclonal B cell immunohistological staining. Immunoglobulin gene rearrangement was present in both specimens.Conclusions: The orbital tumor resected in 1986 was a low-grade malignant lymphoma which disseminated systematically 11 years later. This case shows a long-term course of orbital lymphoproliferative lesion with positive immunoglobulin gene rearrangement. It also shows the importance of follow-up over 10 years in the case of low-grade malignant lymphoma of the ocular adnexa.

Activation of the TCL1 protein in B cell lymphomas

The TCL1 gene, localized near the break point of chromosome 14q32.1 often involved in T cell leukemias, is also expressed in normal precursor T and B cells, and B cell lymphoma cell lines. We investigated the expression of the TCL1 protein in various types of B cell lymphomas according to the Revised European-American Classification of Lymphoid neoplasms. Paraffin-embedded tissue sections of lymphoma specimens were subjected to TCL1 immunohistochemistry, and positivity was scored on a three-tiered scale: - (< 25% cells), + (25-50% cells), and ++ (> 50% cells). The TCL1 protein was expressed in low-grade B cell lymphomas including mucosa-associated lymphoid tissue type in ocular adnexa (18/20, 90%). It was also expressed in follicular, lymphoplasmacytic, and mantle cell lymphoma, but not in high-grade diffuse large B cell lymphoma (2/11, 18%). These data suggest that the expression of the TCL1 gene characterizes low-grade B cell lymphomas, and may be involved in certain processes of lymphomatogenesis.

[A case of orbital lymphoproliferative lesion diagnosed as malignant lymphoma after recurring 11 years later]

BACKGROUND

Most primary lymphoproliferative lesions in the ocular adnexa, including the eyelid, conjunctiva, and orbit, are diagnosed as low-grade malignant lymphomas. Recurrence and dissemination of these tumors are rare in Japan. The long-term prognosis for this disorder still remains to be clarified.

CASE AND METHOD

A 53-year-old woman was first referred to us for right orbital tumor in 1986. After subtotal resection of the tumor, the patient received no additional treatment. She visited us in 1997 with the complaint of bilateral orbital tumor. Biopsied specimens were examined histologically using hematoxylin-eosine and immunohistological staining. Southern blot hybridization was used to detect immunoglobulin gene rearrangement. The paraffin-embedded specimen obtained in 1986 was also examined for immunoglobulin gene rearrangement using nested polymerase chain reaction technique.

FINDINGS

The specimens from 1997 and 1986 were both diagnosed as lymphoid type of inflammatory pseudotumor, based on polyclonal B cell immunohistological staining. Immunoglobulin gene rearrangement was present in both specimens.

CONCLUSION

The orbital tumor resected in 1986 was a low-grade malignant lymphoma which disseminated systemically 11 years later. This case shows a long-term course of orbital lymphoproliferative lesion with positive immunoglobulin gene rearrangement. It also shows the importance of follow-up over 10 years in the case of low-grade malignant lymphoma of the ocular adnexa.

Mutations of p53 in thyroid carcinoma with an insular component

Thyroid carcinoma with an insular component (TCIC) is considered noteworthy in view of its peculiar histopathological features and clinicopathological behavior. The purpose of the present study was to clarify the rate of mutation in the p53 gene in TCIC as compared with rates in papillary and follicular carcinomas of the thyroid. Formalin-fixed and paraffin-embedded blocks of tissue from 46 cases of TCIC were analyzed. DNA was extracted from tissues and exons 5 through 8 of the p53 gene were amplified by the polymerase chain reaction. Mutations were detected by analysis of single-strand conformation polymorphism. Of the 46 cases of TCIC, 6 had a mutation in exon 5, 2 in exon 7, and 5 in exon 8, while 1 case had mutations in all exons examined. The mutation rate of the p53 gene in TCIC was 38%. Immunostaining revealed overexpression of p53 in nuclei that were mainly in areas of the insular component rather than in surrounding areas of well-differentiated carcinoma. The frequency of positive immunostaining in TCIC was 53%. Considering that TCIC is intermediate between papillary plus follicular carcinoma and anaplastic carcinoma in terms of survival and the rate of mutation of the p53 gene, we can speculate that mutation in the p53 gene might be associated with the insular component and might play an important role in the clinicopathological behavior of thyroid carcinoma.

Morules with biotin-containing optically clear nuclei in colonic tubular adenoma

Morules have been reported in pulmonary endodermal tumors (PET) resembling fetal lung, in thyroid carcinoma, and in endometrial and colonic neoplasms. A morule has biotin-containing optically clear nuclei (OCN) in PET and thyroid carcinoma. Biotin-containing OCN have been also reported in endometrial tissue during pregnancy and in endometrioid carcinoma of the ovary, and it has been postulated that morules or OCN develop under the influence of female sex hormones. The authors report here the first case, to their knowledge, of morules with OCN in a colonic adenoma from a 68-year-old man. The colonic polyp consisted of ordinary tubular adenomatous tissue and morules. Many cells in the morules contained OCN. The OCN were immunopositive for biotin and reacted with streptavidin. The neoplastic cells in the morules were immunopositive for oncofetal antigens. Serum levels of female sex hormones were within the normal range, and no cells in the adenoma were immunopositive for receptors for progesterone and estrogen. The results indicate that OCN are rich in biotin and that morules may be embryologically immature elements that develop independently of influence by female sex hormones.

Changing trends and prognoses for patients with papillary thyroid cancer

OBJECTIVE

To analyze differences in the demographic backgrounds, and in treatments, prognosis, and risk factors of patients with papillary thyroid cancer operated on from 1965 to 1990, by dividing them into 3 chronological groups.

DESIGN

Retrospective cohort study of 2423 patients with papillary thyroid cancer (tumor size, > or = 10 mm) who underwent curative surgery at the Noguchi Thyroid Clinic, Oita, Japan.

SETTING

A center for the treatment of thyroid disease, at which about 1400 thyroid operations are performed per year.

PATIENTS

There were 596 patients treated during from January 1, 1965, to December 31, 1973; 964 patients treated from January 1, 1974, to December 31, 1982; and 959 patients treated from January 1, 1983, to December 31, 1990.

RESULTS

Of the 2519 patients treated, 96 were excluded from the study because they had undergone noncurative surgery. Therefore, the analyses are based on data for 2423 patients who underwent curative surgery. Three groups were defined as follows: group 1, underwent surgery during the period 1965-1973 (n = 577); group 2, underwent surgery during the period 1974-1982 (n = 924); and group 3, underwent surgery during the period 1983-1990 (n = 922). The mean age of the patients in group 1 was 42.4 years, in group 2, 45.0 years, and in group 3, 47.8 years. The mean tumor size was 30.4 mm, 26.5 mm, and 24.6 mm, respectively, for groups 1, 2, and 3. The 10- and 20-year disease-specific survival rates were significantly improved from group 1 (95.5% and 90.3%, respectively) to group 2 (97.8% and 93.9%, respectively), and the 10-year rate was significantly improved for group 3 (98.2%). In the multivariate analysis, age, sex, tumor size, and gross nodal metastasis were significant predictors of survival for group 1; however, only age and gross nodal metastasis were significant for group 3.

CONCLUSIONS

Over time, papillary thyroid cancer has become diagnosed at an earlier stage, but the age of the patients at diagnosis is older. The disease-specific survival rate was significantly improved, mainly owing to earlier treatment, and the change in the risk factor profile for cancer mortality may be due to the changes in the demographic backgrounds and diagnostic and therapeutic modalities. These considerations derived from risk factor analysis should be considered for treating the patient and for the prediction of patient survival.

Ultrastructural studies on selected elements of the extracellular matrix in the developing rat lung alveolus

As the respiratory system adapts to the extrauterine life, the extracellular matrix (ECM) plays an important structural and regulatory role during its development. Therefore the purpose of this investigation was to analyze ultrastructurally several elements of extracellular connective tissue during the process of rat lung development. Morphological observations were mainly focused on the terminal part of respiratory system. To outline different components of connective tissue network, several ultrastructural techniques were used (both histochemical and immunohistochemical). The distribution and amount of the following proteins were studied: laminin, collagen type IV, collagen fibrils (CFs), elastic fibers (EFs) and fibronectin (FN). Additionally localization of glycosaminoglycans (GAGs) was examined. The present study deals with four periods of lung development: pseudoglandular, canalicular, saccular and alveolar. In all these stages localization and amount of ECM components change rapidly. In early periods of lung development, the amount of connective tissue fibers was low, basement membranes (BMs) were incomplete, and FN was distributed nearly uniformly. Later when the process of lung alveoli formation begins, the number and thickness of both CFs and EFs rapidly increased, BMs became complete, the content and distribution of FN were irregular. In all stages of lung development GAGs were distributed in BMs and among connective tissue fibers. The results described in the present study summarize morphologically ECM changes occurring during formation of lung alveolus.

Chronic thyroiditis as a favorable prognostic factor in papillary thyroid carcinoma

A subgroup of patients with papillary thyroid carcinoma (PTC) also has chronic thyroiditis (CT) as an associated disease of the thyroid. To assess the prognostic value of CT in patients with PTC, we reviewed the histological slides of 2225 patients with PTC who had undergone surgery between 1971 and 1992. Of the 2225 patients, 692 were excluded from the analysis because regional lymph nodes and/or nonneoplastic thyroid tissues were unavailable for histological assessment. The series included 281 patients with CT in nonneoplastic thyroid tissue and 1252 without CT. We performed statistical analyzes by the log-rank test and Cox's proportional-hazard method. Sixty-two (5.0%) of the 1252 patients without CT died of metastatic disease during the follow-up period and the relapse-free 10-year survival rate was 85%. By contrast, only 2 (<1.0%) of the 281 patients with CT died, and their relapse-free 10-year survival rate was 95%. The difference between patients with CT and those without CT in terms of relapse-free and overall survival was statistically significant (p < 0.0001). Risk factors for unfavorable outcome were age 45 years or more, absence of psammoma bodies, and absence of CT (p < 0.0001), followed by vascular invasion (p = 0.0007), male sex (p = 0.0013), and metastasis to regional lymph nodes (p = 0.047). Multivariate analysis indicated that all of these factors with the exception of gender were independent factors in the final model for overall survival. Chronic thyroiditis in the nonneoplastic thyroid of patients with PTC is a powerful prognostic factor for both relapse-free and overall survival.

Expression of splice variants of CD44 in thyroid neoplasms derived from follicular cells

Isoform expression of CD44 in follicular carcinoma (FC) of the thyroid was analyzed by immunohistochemical staining and compared to the isoforms in follicular adenoma (FA) and papillary carcinoma (PC) of the thyroid. Variant isoforms of CD44 (CD44v) were detected in these neoplastic cells but not in non-neoplastic cells. CD44v6 was expressed in PC with nodal metastasis and also in FC at significantly higher frequencies than those in PC without metastasis and FA. The frequency of expression of CD44v3 was significantly higher in PC with nodal metastasis than in PC without metastasis. The reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blotting analysis revealed the presence of a transcript for a variant of CD44 that contained variant exon 6 in FA, FC and PC. DNA sequencing of the products of RT-PCR yielded three species of cDNA for CD44v. One of the cDNA corresponded to a transcript that contained variant exon 6. These results suggest that immunohistochemical staining and RT-PCR with Southern blotting analysis for CD44v6 might be a useful diagnostic tool for the differentiation of FC from FA and that the expression of CD44v3 and CD44v6 might be important for the development of nodal metastasis in cases of PC.

Antibiotic susceptibility of enterohemorrhagic Escherichia coli O157:H7 isolated from an outbreak in Japan in 1996

The antibiotic susceptibilities of 43 strains of Escherichia coli O157:H7 identified in the summer of 1996 in Japan were investigated. Growth of 90% of O157 strains was inhibited at a concentration of < or = 0.5 micro/ml by several agents including fosfomycin with glucose-6-phosphate.

Hermaphroditic Freshwater Clams in the Genus Corbicula Produce Non-Reductional Spermatozoa With Somatic DNA Content

Hermaphroditic freshwater clams in the genus Corbicula produce non-reductional spermatozoa. The DNA content of spermatozoa was almost identical with that of somatic cells in C. leana from Mie Prefecture, Japan. Hermaphroditic C. aff. fluminea from Saga Prefecture and C. fluminea from Taiwan also produce non-reductional spermatozoa. On the other hand, spermatozoa of the dioecious C. sandai had half the DNA found in somatic cells. Analysis of chromosome numbers suggests that C. leana (3n = 54 in somatic cells and 18 in meiotic cells) from Mie Prefecture and C. aff. fluminea (2n = 36 in gills and 18 bivalents in meiotic cells) from Saga Prefecture are triploids and diploids, respectively. C. leana, C. aff. fluminea, and C. fluminea may lack either first or second meiosis, resulting in non-reductional spermatozoa. We assume that gynogenetic reproduction occurs in both species; maternal chromosomes are also nonreductional, and spermatozoa activate development of the eggs, but do not contribute to the offspring.

Thyroid cancer associated with adenomatous goiter: an analysis of the incidence and clinical factors

We evaluated the incidence of thyroid cancer in patients with adenomatous goiter and investigated the clinical factors distinguishing patients with occult thyroid cancer, defined as a tumor size smaller than or equal to 10 mm, from those with clinical thyroid cancer, defined as a tumor size larger than 10 mm. Of 835 patients with histologically confirmed adenomatous goiter, 256 (30.7%) also had thyroid cancer, being occult in 137 patients and clinical in 119 patients. There was no correlation between the maximum size of the thyroid cancer tumor and the age of the patient, and the percentage of patients with thyroid cancer in each group was not influenced by age. There were no significant differences in age, sex, the serum concentrations of free triiodothyronine, free thyroxine, thyrotropin, and thyroglobulin, or the urinary iodine creatinine ratio. The frequency of calcified lesions being detected by ultrasonography (US) and/or neck X-ray in the patients with clinical thyroid cancer was significantly greater than that in those with occult cancer at 83% vs 57%, respectively (P < 0.0001). This study disclosed a high prevalence of thyroid cancer associated with adenomatous goiter, and the results suggest that a considerable number of associated carcinomas remain occult. The detection of calcification in the thyroid gland is one of the surgical indications for patients with adenomatous goiter.

A ciliated cyst as a component of pleomorphic adenoma of the parotid gland

A large cyst, lined with ciliated cells (ciliated cyst), was found as a component of a pleomorphic adenoma of the left parotid gland in a 34-year-old Japanese man. The dimensions of the tumor were 25 x 33 mm and it consisted of a solid mass with a centrally located cyst 20 x 23 mm, which contained yellowish-brown material of muddy consistency. The tumor was encapsulated and the solid mass had features typical of a pleomorphic adenoma. The inner surface of the cyst was lined with ciliated cells and scattered mucus-secreting cells in addition to cuboidal-to-flattened cells. In some regions, the neoplastic cells of the pleomorphic adenoma were exposed to the cavity of the cyst. A histological transformation from ciliated cells to pleomorphic adenomatous cells was also observed. These findings indicated that the ciliated epithelium was an element of the tumor. This is the first report, to our knowledge, of a ciliated cyst derived from some elements of a pleomorphic adenoma of the salivary gland.

Effects of acidic and basic fibroblast growth factors on cell proliferation in pleomorphic adenoma of the parotid gland

Localization and biochemical characteristics of acidic and basic fibroblast growth factor (aFGF and bFGF) were studied in the normal parotid gland (NPG) and in pleomorphic adenoma (PA). In addition, the effects of these factors on proliferation activity were investigated in cultured PA cells. aFGF and bFGF were detected immunohistochemically in 62% and 58% of NPG and 44% and 58% of PA, respectively, and they localized in the cytoplasm of the ductal segments of the NPG, and of the tubular, trabecular and squamous components of PA. Both aFGF and bFGF, each with a molecular weight of 18 kDa, were identified in PA using heparin-sepharose chromatography and Western blot analysis. Both recombinant human aFGF and bFGF stimulated [3H]-thymidine incorporation by cultured PA cells. These results indicated that aFGF and bFGF, probably produced by neoplastic cells, play important roles in the proliferation of PA of the parotid gland.

Rhabdomyosarcoma of the urachus. A case report

BACKGROUND

Rhabdomyosarcoma of the urachus is extremely rare, and only two cases have been reported. Cytologic, histologic, immunochemical and electron microscopic findings in embryonal rhabdomyosarcoma of the urachus are presented.

CASE

Embryonal rhabdomyosarcoma of the urachus developed in a 2-year-old boy. Imprint smears prepared prior to a histologic examination for a rapid report contained many malignant cells isolated or in clusters in a myxoid background. They were uniformly small, with round to oval nuclei and scant cytoplasm, and immunohistochemically positive for desmin and alpha-sarcomeric muscle actin but negative for myoglobin. This tumor was diagnosed cytologically as embryonal rhabdomyosarcoma because of its skeletal muscle origin and because of its similarity to one of the so-called small round cell tumors of childhood. Histologic examination confirmed the cytologic diagnosis.

CONCLUSION

Cytologic, histologic and electron microscopic findings were identical to those described previously for embryonal rhabdomyosarcoma at other sites. In immunochemical examinations, cytologic samples fixed in ethanol are more useful than histologic ones fixed in formalin. Then, in order to differentiate poorly differentiated rhabdomyosarcoma from other small round cell tumors in children, desmin and alpha-sarcomeric actin, rather than myoglobin, are recommended.

Cytoplasmic biotin-like activity interferes with immunohistochemical analysis of thyroid lesions: a comparison of antigen retrieval methods

Cytoplasmic biotin-like activity was identified in formalin-fixed and paraffin-embedded human thyroid lesions by immunostaining for biotin by use of the peroxidase-antiperoxidase method or by peroxidase-labeled streptavidin alone. The reactivity of cytoplasmic biotin-like activity was markedly enhanced both by pretreatment with trypsin and after heating by autoclaving. Of 208 thyroid lesions, 93 showed positive immunostaining for biotin with use of trypsin pretreatment. The positive incidence of cases and positive cell ratio were highest in papillary carcinoma, followed by follicular carcinoma but lowest in the lethal types of thyroid carcinoma: anaplastic carcinoma, squamous cell carcinoma and poorly differentiated insular carcinoma. We conclude that cytoplasmic biotin-like activity in the common thyroid neoplasms should be considered as an interfering factor for immunostaining with avidin-biotin combined with selected antigen retrieval methods and with in situ hybridization with biotinylated probes.

Sarcomatoid hepatocellular carcinoma with osteoclast-like giant cells: case report and immunohistochemical observations

Hepatocellular carcinoma (HCC) with osteoclast-like giant cells (OGC) developed in the cirrhotic liver of a 42-year-old male. Serum protein induced by vitamin K absence or antagonist II was elevated preoperatively. The patient died of the disease on the 28th postoperative day. Histologically, the tumor consisted of OGC and mononuclear cells (MC). The OGC were characterized by benign-appearing nuclei, whereas the MC had atypical nuclei with a considerable number of mitoses. A vaguely trabecular pattern was observed in the focal area of the tumor, but no evidence of overt HCC was found. Immunohistochemical analysis revealed that both OGC and MC were diffusely positive for histiocytic and mesenchymal markers. Some MC were focally positive for cytokeratins 7, 8 and 19, and for albumin. Our clinical, histological and immunohistochemical findings suggest that the MC were derived from hepatocytes, with some mesenchymal features, but the OGC were non-neoplastic and reactive histiocytes.

Immunohistochemical study on tissue transglutaminase and copper-zinc superoxide dismutase in human myocardium: its relevance to apoptosis detected by the nick end labelling method

The influence of free radicals on apoptosis was studied in the human heart; 45 autopsy cases were examined by the nick end labelling method (NELM) that detects DNA fragmentation. Immunostaining for copper-zinc superoxide dismutase (CuZn-SOD) and tissue transglutaminase (tTG) induced frequently during apoptosis were also studied. Positive immunoreaction for tTG was detected in mucinous degeneration of myocardial cells; these same cells were also positive for CuZn-SOD but negative for NELM. Myocardial cells showing basophilic alterations after haematoxylin and eosin staining were also positive for CuZn-SOD but negative for the other markers examined. Positive nuclear reaction by NELM was only observed in myocardial cells showing contraction band necrosis or irregularly shaped nuclei surrounding recent or long-standing infarcted foci. In these the other two markers were negative. Since mucinous degeneration lacks the distinguishing morphological features of apoptosis, immunoreactive tTG in this lesion may not imply that the cells are undergoing apoptosis. tTG can be induced in non-apoptotic conditions and may not be involved in apoptosis induced by infarction. Histological disassociation between CuZn-SOD expression and apoptosis suggests the possibility of a cytoprotective role played by endogenous CuZn-SOD against free radical generation in the human heart.

Cytologic features of solid and cystic tumor of the pancreas

OBJECTIVE

To describe the cytologic features of solid and cystic tumor of the pancreas.

STUDY DESIGN

Cytologic features of four cases of solid and cystic tumor of the pancreas (SCT) were reported and compared with those of three cases of islet cell tumor of the pancreas.

RESULTS

Aspiration and imprint cytology of the tumor cells obtained from three cases of SCT showed papillary structures or rosette formations in part and demonstrated uniformly round to oval nuclei that contained finely granular chromatin, a fairly distinct nucleolus and a scant to moderate amount of granular or vesicular cytoplasm. Another case of SCT consisted of multinucleated giant cells with coherent chromatin as well as mononuclear cells with nuclear grooves. Islet cell tumor consisted mainly of clustered or isolated uniform mononuclear cells with rosette formations but without a papillary structure and occasional multinucleated giant cells in all cases. The nuclei of islet cell tumors had peculiar, fine chromatin aggregates with a "salt-and-pepper" appearance and slightly enlarged nucleoli.

CONCLUSION

SCT is cytologically distinguishable from islet cell tumor in spite of having many cytologic features in common with it.

Effects of gastrin on the histamine-secretory and proliferative activity of cultured carcinoid cells derived from the stomach of the rodent Mastomys natalensis

The effects of gastrin on the synthesis and release of histamine and on cellular proliferation were investigated in a homotransplantable carcinoid tumor implanted in the rodent Mastomys natalensis and in cultured cells derived from the tumor. The homotransplanted tumor was immunopositive for histamine, synaptophysin and protein gene product 9.5, and its cells contained numerous secretory granules that were visualized by electron microscopy. When carcinoid cells were cultured in a medium with a high concentration of gastrin-I (10(4) pg/mL) for 7 days, large electron-dense secretory granules were characteristically observed in the cytoplasm. By contrast, only a few such granules and numerous secondary lysosomes were seen in cells that had been cultured in the same medium without gastrin-I. A high concentration of gastrin-I (10(4) pg/mL) significantly increased the release of histamine into the culture medium from the carcinoid cells compared with the control (P < 0.05). Cellular proliferation, as determined by monitoring the incorporation of [methyl-3H]-thymidine into the carcinoid cells increased significantly at lower concentrations of gastrin-I (10(2) and 10(3) pg/mL), (P < 0.05). At higher concentrations (10(4) pg/mL or more), gastrin-I had no effect on proliferation. These findings indicate that gastrin stimulates the synthesis and release of histamine by carcinoid cells, as well as their proliferation.