Responses of monkeys with pollinosis to two major allergens of Japanese cedar pollen

We examined the responses of two Japanese monkeys with pollinosis to two major allergens (Cry j 1 and Cry j 2) of Japanese cedar pollen. The two monkeys (A and B) had specific IgE antibodies to the allergens and showed a strong positive reaction to both of them in the intradermal test. In the histamine release test with peripheral blood mononuclear cells (PBMC), monkey A showed a typical pattern similar to that seen in human patients, while monkey B released a low level of histamine. The proliferative response of PBMC to both allergens in monkey A was weak, but was typical in monkey B. From clinical as well as immunological points of view, these monkeys may be a suitable animal model for Japanese cedar pollinosis in humans.

Insular component as a risk factor of thyroid carcinoma

Forty-four thyroid carcinomas with an insular component (IC) were reviewed from 2457 tumors diagnosed as papillary (PC) or follicular carcinoma (FC). These tumors were classified as FC with an IC (FCIC; 30 cases) and PC with an IC (PCIC; 14 cases). Both tumors were composed of solid cell nests in some areas and had a tendency toward a characteristic nuclear size: FCIC had a small nucleus and PCIC contained a nucleus of an intermediate type or a large nucleus similar to that of PC, although there were numerous tumors with an exceptional nuclear size. The mean age and tumor diameter were the highest and largest in FCIC, respectively, followed by PCIC. Among the 44 cases, 17 patients died of the disease, two were alive with the disease and 18 were alive without the disease. From 13 clinicopathological factors, the presence of an IC, age, non-encapsulation, tumor size, vascular invasion and necrosis were found to be independent variables for actual prognosis of FC and PC based on univariate analysis followed by multivariate analysis. The results of the present study indicate that the presence of an IC is an independent aggressive prognostic factor for patients with PC and FC.

Oncofetal expression of blood group-related antigen on morules in thyroid carcinoma

Morule formation in association with characteristic biotinrich 'optically clear nuclei' were found in 7 of 2514 cases of thyroid carcinoma. The seven patients were all young females aged from 20 to 36 years who were suffering from either papillary carcinoma (six cases) or follicular carcinoma (one case). The ABH (O) blood group (BG) types were A in three, AB in two and H(O) in two patients. Immunohistochemical study revealed that ABH(O) and Lewis BG antigens were expressed more specifically on morules than on ordinary neoplastic cells of papillary or follicular carcinoma. Lewis BG antigens tested in the present study were as follows: CA50, CA19-9, stage-specific embryonic antigen 1 (SSEA-1), and sialyl SSEA-1. Ulex europaeus agglutinin I (UEA-I) histochemistry showed a positive reaction on all the morules of blood groups A and H(O) patients, but yielded completely negative results on the morules of type AB patients. Sequential digestion by neuraminidase and alpha-galactosidase unmasked the reactivity for UEA-I even on the morules of type AB patients. The consistent reactivity for UEA-I on the morules seemed to be related to specific expression of BG antigens, which were characterized as oncofetal expression. It is suggested that the morules in thyroid carcinoma might be a kind of fetal component induced by the differentiation of the neoplastic cells to the stage of immature embryonic cells.

Quantitative age-related changes in apical dendrites and dendritic spines of CA1 pyramidal neurons among senescence accelerated mice (SAMP1TA/Ngs)

SAMP1TA/Ngs, a substrain of senescence accelerated mouse, is a useful animal model for research on brain dysfunction due to senescence. In a previous study it was reported that the age-related changes in basal dendrites and spines of CA1 pyramidal neurons coincide with the behavioral characteristics found in SAMP1TA/Ngs. The goal of the present study was to investigate morphological changes in apical dendrites and dendritic spines of CA1 pyramidal neurons among 3-, 5-, 7-month-old SAMP1TA/Ngs. Pyramidal neurons of the hippocampus were stained by the rapid Golgi method, and the number of apical dendrites, the number of their spines and the density of the dendritic spines were evaluated. The number and density of the spines of apical dendrites were significantly higher at 5 months than at 3 or 7 months of age. We propose that the low number of dendritic spines in 3-month-old animals was caused by immaturity, while the changes in the density and number of dendritic spines in 7-month-old mice were due to accelerated aging. The data on the morphology of apical dendrites are a useful complement to the results reported previously. The findings of the present study also support the hypothesis that this model mouse demonstrates changes in respective developmental stages, i.e. immaturity, adulthood and senescence. This pattern of postnatal growth has special meaning because it indicates the usefulness of the strain in the study of geriatric disorders in humans.

Intake ratio of water-insoluble dietary fiber to the water-soluble one in Japanese: an estimation on dietary records and the secular consideration on the national nutrition survey

Thirty-four foods were analyzed in order to determine the content of water-soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Using the results with the standard table for 227 foods, the intake ratio of IDF/SDF of an average Japanese was calculated for the period 1946-1990. The ratio was 3.22 in 1990 as calculated on the food intakes shown in the national nutrition survey, and the secular change was not detected since 1946 when the ratio was 3.30. The ratio was also shown to be well preserved between types of households including the age of the head. Using dietary records of 60 healthy city workers (average 42.8 years) for 4 weeks, however, the weekly average ratio for an individual was found to vary in the range of 2.25-5.13 although the total average for 60 individuals was 3.33. Thus, the well preserved IDF/SDF intake ratio for an average Japanese showed, on the contrary, a wide variation of food selection between each person.

c-myc expression is associated with increased proliferation activity in thyroid follicular cells of Graves' disease as stimulated by autoantibodies

Expression on thyroid follicular cells of HLA-DR, c-myc protein and proliferating cell nuclear antigen (PCNA) was examined immunohistochemically in 28 cases of Graves' disease (GD) and in 29 cases of Hashimoto's thyroiditis (HT). Immunoreactivity for PCNA in GD was seen not only in follicular cells adjacent to a lymphocytic infiltration, where the follicular cells were positive for HLA-DR, but also in hyperplastic follicular cells without the infiltration. The distribution of expressed c-myc protein was similar to that of PCNA in GD but not in HT. Semiquantitatively graded degrees of lymphocytic infiltration and expression of HLA-DR, c-myc and PCNA in GD showed a high correlation with one another. However, the degrees of c-myc expression in HT showed no significant correlation with any other degrees. Intraperitoneal injection of bovine TSH or of immunoglobulins derived from a patient with GD in rabbits induced hyperplastic change of thyroid follicular cells, as reflected in PCNA and c-myc immunoreactivity, as well as strong peroxidase and acid phosphatase activity. Immunization with synthesized peptide of thyrotropin receptor also exhibited the same results in the rabbit thyroids. Our results indicate that c-myc expression on follicular cells of GD may reflect a stimulation by autoantibodies mediated through the thyrotropin receptor.

Second case of zoonotic Onchocerca infection in a resident of Oita in Japan

A non-gravid female Onchocerca was found in histopathological sections of a biopsy specimen taken from a painful nodule in the wrist of a 57-year old woman in Oita, in southern Japan. Six species of Onchocerca have been found in animals in Japan: two in wild bovids, one in equids, and three in domestic bovids of which one, Onchocerca sp., is only known by the microfilaria and infective stage. Distinctive morphological features of the worm, including a three-layered thick cuticle with prominent annular ridges at wide intervals, high somatic muscles and narrow lateral chords, resembled those of O. gutturosa, one of the three bovine Onchocerca species transmitted in the Oita region. However Onchocerca sp., which is also transmitted in this region, cannot be excluded. An ELISA test of the patient serum suggests that infections by Onchocerca spp. might be distinguished from those by Dirofilaria immitis, of which the number of human cases is increasing in Japan.

Small carcinomas of the thyroid. A long-term follow-up of 867 patients

OBJECTIVE

To determine the adequate extent of surgery for small carcinomas of the thyroid.

DESIGN

Retrospective cohort study of 867 consecutive patients with small carcinomas of the thyroid (lesions < 10 mm in diameter) who were operated on at the Noguchi Thyroid Clinic, Oita, Japan, between 1965 and 1987. Mean follow-up was 12.8 years.

SETTINGS

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

PATIENTS

Thyroidectomy was performed in patients with a preoperative diagnosis of Graves' disease, Graves' disease with nodules, solitary thyroid nodules, multinodular goiters, cysts, chronic thyroiditis and small carcinomas of the thyroid, in 394, 22, 136, 193, 18, 28, and 76 patients, respectively.

RESULTS

Operations were conservative. Three patients who had adenomatous nodular goiters underwent total thyroidectomy. Modified radical neck dissection was performed in 66 patients. Of these 66 patients, 30 had grossly noticeable nodal metastases and 17 had microscopic metastases. Another 50 patients underwent selective lymph node excision, and 28 patients had nodal metastases. Recurrence from remnants of thyroid was seen in five patients. They were treated by surgery. Recurrence in lymph nodes was observed in five patients, and four of them were successfully treated. Recurrence in bone was observed in two patients; one with recurrence in the femur was successfully treated. Two patients died with recurrent cancer.

CONCLUSIONS

Small carcinomas of the thyroid can be fatal. Total thyroidectomy is unnecessary. Modified radical neck dissection is unnecessary unless gross nodal metastases are present. Long-term follow-up is mandatory. A

Pulmonary surfactant migrates into the alveolar capillaries of newborn rats: an immunoelectron microscopic study

The goal of the present study was to elucidate the migration of surfactant-like material into the alveolar capillaries of newborn rats. The lungs of experimental animals were studied by ultrastructural techniques-standard electron microscopy as well as immunoelectron microscopy-using antibodies against synthetic polypeptide complementary to the noncollagenous part of surfactant protein A (SP-A). Antibodies exhibited specific reaction with native rat SP-A in Western blot and immunohistochemical analysis. Surfactant was observed in the alveolar space, type II pneumocytes, macrophages, type I pneumocytes, endothelial cells, the extracellular space of the alveolar septa and in the alveolar capillaries. Lamellar structures observed in all elements of the blood-air barrier as well as in the alveolar capillaries were stained positively with anti-SP-A antibodies. Transport of the pulmonary surfactant into the circulatory system was observed more frequently during the first 6-8 h of extrauterine life of newborn rats, although it was also seen in the blood vessels till 48 h after delivery. The results of our investigation suggest that clearance of surfactant via the circulatory system plays an important role in the early postnatal period.

The connective tissue compartment in the terminal region of the developing rat lung. An ultrastructural study

The present study was designed to analyze the connective tissue compartment in the terminal region of the developing rat lung. Lungs of rat fetuses (at 17, 19 and 21 days of gestation) and of newborns (2, 4, 7, 10, 14 and 21 days after birth) were examined by several ultrastructural techniques; staining with tannic acid for elastic fibers (EFs), collagen fibers (CFs) and basement membranes (BMs); staining with ruthenium red for glycosaminoglycans; and immunoelectron microscopy for visualization of collagen type IV, laminin and fibronectin (FN). Dynamic changes in the levels and distribution of the components of the extracellular connective tissue were observed in parallel with the formation and maturation of the alveoli. The terminal regions of the respiratory tract of the rat fetus and of the lungs of early newborns contained few CFs and EFs, and the Bms in these lungs were incomplete. However, strong immunolabeling of FN was observed (in BMs, CFs and in spaces among fibroblasts). Starting from 4 to 7 days newborns had increasing numbers of Cfs and EFs and BMs became more extensive. In rat newborns, immunolabeling specific for FN was weak and irregularly distributed. Furthermore, the present results provide a summary of the changes in connective tissue that occur in the rat lung during different stages of its development, from the pseudoglandular stage, through the canalicular and saccular stages, to the alveolar stage.

Relationship between cell proliferation activity and morphological characteristics of papillary microcarcinoma in the thyroid of Graves' disease

Three hundred and seven lesions of papillary microcarcinoma of the thyroid (PMT), found in 6830 cases of Graves' disease, were reviewed to evaluate the morphological characteristics. The prevalence rate and incidence of multiplicity of PMT in Graves' disease were higher (P < 0.05 and P < 0.005, respectively) in females (4.03% and 0.73%, respectively) than in males (2.68% and 0.12%, respectively). All lesions of PMT were classified histologically into three types: sclerosing non-encapsulated (SNE), non-sclerosing encapsulated (NSE) and non-sclerosing non-encapsulated (NSNE). Comparison of the three types of PMT revealed that the mean age and tumor size of NSNE were less than those of NSE and SNE (P < 0.001 and P < 0.005, respectively), and 13 of 19 lesions less than 1 mm belonged to NSNE. In addition, cell proliferation and expression of estrogen and progesterone receptors were examined immunohistochemically in 257 lesions of PMT. The Ki-67 labeling index of NSE was lower than that of NSNE and SNE (P < 0.005). None of the cases of PMT was positive for estrogen or progesterone receptors. The present study indicated that NSNE may be an early stage in tumor progression, and that fibrous encapsulation has the potential to modify neoplastic cell proliferation.

Morule with biotin-containing intranuclear inclusions in thyroid carcinoma

One thousand and sixty cases of thyroid carcinoma were reviewed to compare morules with squamous metaplasia clinicopathologically and immunohistochemically. Morules and squamous metaplasia were found in five (0.47%) and 32 cases (3.0%) respectively. The five patients with morules were all female (age 20-36 years) including four with papillary carcinoma and one with follicular carcinoma. The 32 patients with squamous metaplasia consisted of 30 females and 2 males (age 14-78 years), all of whom had papillary carcinoma except for one follicular carcinoma. The morules demonstrated characteristic 'optically clear nuclei' (OCN), which ultrastructurally showed filamentous structures in the nuclei. The OCN were immunohistochemically demonstrated to contain intranuclear biotin. Furthermore, the morule often accompanied with the OCN was positive for Ulex Europaeus agglutinin l (UEA-l) but negative for bovine muzzle epidermal keratin (EK). On the contrary, squamous metaplasia unaccompanied with the OCN was negative for UEA-l, but positive for EK. Follow-up information revealed that one of the five patients with morules had died of the disease, one was alive with pulmonary metastasis, and three were disease-free. Eight of 32 patients with squamous metaplasia had died of the disease; of the others who were alive, four patients have had recurrence.

Aldosterone inhibits nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 beta

We investigated the effects of aldosterone on nitric oxide (NO) synthesis in vascular smooth muscle cells. We measured the production of nitrite, a stable metabolite of NO, and the expression of inducible NO synthase mRNA and protein in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1 beta (10 ng/ml) for 24 h caused a significant increase in nitrite generation. The interleukin-1 beta-induced nitrite production by vascular smooth muscle cells was significantly inhibited by aldosterone in a dose (10(-9) approximately 10(-6) M)-dependent manner. Incubation with interleukin-1 beta for 12 approximately 24 h caused inducible NO synthase mRNA expression in vascular smooth muscle cells, whereas aldosterone had a suppressive effect on its expression. Aldosterone also decreased interleukin-1 beta-induced NO synthase protein accumulation. These results indicate that aldosterone inhibits NO synthesis under interleukin-1 beta-stimulated conditions in vascular smooth muscle cells.

Angiotensin II transduces its signal to focal adhesions via angiotensin II type 1 receptors in vascular smooth muscle cells

In cultured vascular smooth muscle cells (VSMCs), angiotensin II (Ang II) stimulated tyrosine phosphorylation of several proteins including a cluster of 70-80-kDa proteins as assessed by anti-phosphotyrosine immunoblotting. These 70-80-kDa proteins were identified as a focal adhesion-associated protein, paxillin, by anti-paxillin immunoprecipitation. Ang II-stimulated tyrosine phosphorylation of paxillin was detectable within 1 min and maximal at around 10 min and was concentration dependent (half-maximal effect at around 1 nM). Ang II also stimulated tyrosine phosphorylation of focal adhesion kinase in a time- and concentration-dependent manner. The Ang II type 1 (AT1) receptor antagonist, CV-11974, but not the Ang II type 2 receptor antagonist, PD123319, inhibited these reactions. These results indicate that Ang II transduces its signal to focal adhesions via AT1 receptors in cultured VSMCs.

Contribution of Epstein-Barr virus to development of malignant lymphoma of the thyroid

Epstein-Barr virus (EBV)-related mRNA, their products and apoptosis were investigated in 32 cases of malignant lymphoma of the thyroid (MLT) and 30 cases of Hashimoto's thyroiditis (HT) by in situ hybridization, immunohistochemistry and nick end labeling method on routinely processed tissue sections. In MLT, EBV-encoded small RNA (EBER) were detected in three cases, consisting of a follicular, predominantly large cell type (FL), a diffuse, large cell type (DL) and a large cell, immunoblastic type (IBL). In EBER-positive cases, IBL that was positive for T cell marker, exhibited neither BamHl H Left Frame 1 (BHLF1) transcript, EBV-encoded latent membrane protein (LMP) nor BamHl Z Left Frame 1 (BZLF1) gene product (ZEBRA), whereas both BHLF1 and ZEBRA were found in a small portion of the tumor cells in the FL and DL that expressed B cell marker and LMP. Apoptotic cells were observed in only a few lymphocytes in HT, and in a few non-neoplastic lymphocytes and various numbers of lymphoma cells in MLT. The apoptotic cell ratio of MLT tended to be higher in lower grade lymphomas. These results suggest that EBV may participate in the malignant transformation from HT to MLT.

The kinetics of copper-zinc superoxide dismutase in experimentally induced ischemia-reperfusion injury of the canine jejunum

In this study, the kinetics of copper-zinc superoxide dismutase (CuZn-SOD) in experimentally induced ischemia-reperfusion injury of the canine jejunum were examined using immunohistochemical procedures, and evaluated as an index for the viability of transplants. A pedicled jejunal graft was subjected to arterial reperfusion after clamping the supplying blood vessels for 30 min. Under nonischemic conditions, some of the goblets in the goblet cells and the mucin covering the surface of the villi were stained positively with luxol fast blue, von Kossa, and immunohistochemistry for CuZn-SOD. Between 5 and 30 min after reperfusion, the appearance of goblets with positive immunoreaction for CuZn-SOD in the intestinal glands and the disappearance of these goblets in the villi were observed in the grafts of animals that received arterial reperfusion after 30 min of clamping of the arteries and veins at room temperature. Thereafter, the former disappeared gradually and the latter returned toward the nonischemic condition. The administration of allopurinol led to a decrease in tissue damage and a significantly higher number of goblets with positive immunoreaction for CuZn-SOD than in untreated animals. Furthermore, the goblets in the intestinal glands showed a negative reaction for CuZn-SOD 5 to 30 min after reperfusion. Preservation at 4 degrees C during ischemia revealed similar results to those observed in the animals given allopurinol. Thus, the distribution and intensity of CuZn-SOD positive goblets seems to be a useful indicator for the evaluation of tissue damage induced by free radicals mediating ischemia-reperfusion injury.

Alteration in gastric nerve fibers containing gastrin-releasing peptide in relation to the gastrin-producing cell population after truncal vagotomy in a rat model

The fine structural alteration in the gastric nerve fibers containing gastrin-releasing peptide (GRP) was studied in relation to the dynamics of gastrin-producing cells (G-cells) after truncal vagotomy in a rat model. The circulating gastrin levels were markedly elevated from the 1st day after vagotomy and the number of G-cells with positive immunoreaction for G17 and G34(1-15) was significantly increased in the vagotomized group. On the 3rd day after vagotomy, the G-cells showed conspicuous ultrastructural changes characterized by hypertrophy of the Golgi complexes and increased numbers of secretory granules. The GRP-positive nerve fibers formed a fine network in the gastric wall and were densely distributed in the oxyntic mucosa close to the blood vessels and showing varicosities composed of either small clear or GRP-positive large vesicles containing an electron-dense core. In the oxyntic mucosa of the vagotomized rats, axonal swelling of the nerves occurred on the 3rd day, and a depletion of GRP immunoreactivity was evidenced by a markedly decreased number of large-cored vesicles on the 7th day, when the serum GRP levels were also found to be markedly elevated. These findings indicate that the alteration in gastric nerve fibers containing GRP after truncal vagotomy may be related to hypergastrinemia and antral G-cell hyperplasia in the rat gastric mucosa.

Angiotensin II inhibits cytokine-stimulated inducible nitric oxide synthase expression in vascular smooth muscle cells

In cultured vascular smooth muscle cells (VSMC), inflammatory cytokines such as interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha stimulated nitric oxide (NO) production via the expression of an inducible type of NO synthase (iNOS). A potent vasoconstrictor, angiotensin II (Ang II), which causes a rapid phospholipase C-mediated phosphoinositide hydrolysis via the Ang II type 1 (AT1) receptor in VSMC, by itself did not stimulate the production of nitrite, a stable metabolite of NO, but dose dependently inhibited the IL-1 beta-induced nitrite production. This inhibitory effect of Ang II was blocked by an AT1 receptor antagonist, CV-11974, but not by an Ang II type 2 receptor antagonist, PD 123319. The presence of Ang II during the early induction phase of iNOS was required for this inhibition. Consistently, Ang II suppressed IL-1 beta-induced increases in iNOS mRNA and protein levels. Ang II also inhibited increases in nitrite production and iNOS mRNA and protein levels caused by tumor necrosis factor alpha. A protein kinase C-activating phorbol ester, phorbol 12-myristate 13-acetate, and a membrane-permeable diacylglycerol, 1,2-dioctanoyl-glycerol, similarly inhibited the IL-1 beta-induced nitrite production and iNOS mRNA and protein expression, although repetitive additions were needed in the case of diacylglycerol. These results indicate that Ang II negatively modulates cytokine-induced NO production by blocking iNOS expression via the AT1 receptor in VSMC and suggest that protein kinase C could be involved in this process.

Immunohistochemical localization of acidic and basic fibroblast growth factors in human benign and malignant thyroid lesions

The localization of acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) was investigated immunohistochemically in human benign and malignant thyroid lesions. Immunostaining for aFGF and bFGF displayed diffuse or granular deposits of the reaction products in the cytoplasm of neoplastic cells, especially in the marginal region of follicular adenoma, follicular carcinoma and papillary carcinoma. All lesions except for diffuse hyperplasia, which was completely negative in immunostaining for all antibodies, showed an increased immunostaining for bFGF (Ab-1) over that of aFGF and bFGF (Ab-2). Basement membranes of follicular and papillary structure and the fibroblasts located in the stromal tissues were free from immunostaining for all antibodies. The ratio of positive immunostaining for all antibodies was highest in papillary carcinoma, with an incidence of more than 80.0%, followed, in descending order, by widely invasive follicular carcinoma, minimally invasive follicular carcinoma, follicular adenoma and normal thyroid, in which some follicular cells exhibited weak reaction products. aFGF with a molecular weight of 18 kDa was identified in papillary carcinoma of the thyroid. From these data, we concluded that aFGF is synthesized in the neoplastic follicular cells of the thyroid, and aFGF and bFGF may have important roles in the neoplastic proliferation of follicular cells.

Sex chromosome polymorphism and heterogametic males revealed by two cloned DNA probes in the ZW/ZZ fish Leporinus elongatus

In order to study the divergence of teleost sex chromosomes, subtractive cloning was carried out between genomic DNA of males and females of the rainbow trout (XX/XY) and of Leporinus elongatus (ZW/ZZ). Inserts cloned in a plasmid vector were individually tested on Southern blots of DNA of males and females for sex specificity. No sex-specific insert was obtained from trout, but two out of ten inserts cloned from L. elongatus showed sex-specific patterns in this species: one corresponds to a sequence present on both Z and W chromosomes, while the other is W specific. Sequences of these two inserts show neither clear homology with other known sequences, nor an open reading frame. They cross-hybridize with the genomic DNA of Leporinus friderici, but without sex-specific patterns. Twenty-four L. elongatus adults were sexed by gonadal observation, chromosomed examination and Southern hybridization with one or the other insert. Ten males and 11 females had chromosomes and hybridization patterns typical of their sex. One ZW female was recognized as a male with the W-specific probe. This was also the case for two unusual ZW males, one having a male hybridization pattern with the other probe. These three atypical individuals may result from single genetic exchanges between four regions of the Z and the W, giving rise to three atypical W chromosomes. Finding males with such atypical heterochromosomes in a female heterogametic species may indicate that a gradual transition occurs between the heterogametic systems.

Expression of nitric oxide synthase by cytokines in vascular smooth muscle cells

In cultured vascular smooth muscle cells, the baseline mRNA and protein levels of an inducible type of nitric oxide synthase were barely detectable. Interferon gamma, tumor necrosis factor-alpha, and interleukin-1 beta each markedly increased mRNA and protein levels of this enzyme in parallel with the production of nitrite, a stable oxidative metabolite of nitric oxide. Actinomycin D abolished the cytokine-induced increases in mRNA levels and nitrite production. Cycloheximide, which abolished the cytokine-induced increase in nitrite production, had no effect on the interferon-gamma-induced increase in mRNA levels but partially inhibited that induced by interleukin-1 beta and markedly inhibited that induced by tumor necrosis factor-alpha. Transforming growth factor-beta 1, which inhibited the interferon gamma-, interleukin-1 beta-, and tumor necrosis factor-alpha-induced nitrite production, did not affect the increases in mRNA levels caused by these cytokines. Transforming growth factor-beta 1, however, significantly inhibited the increase in protein levels caused by these cytokines. These findings suggest that interferon gamma directly induces the expression of the inducible nitric oxide synthase gene, whereas tumor necrosis factor-alpha and interleukin-1 beta induce it, at least in part, via the induction of intermediary protein(s), and that transforming growth factor-beta 1 inhibits cytokine-induced nitric oxide production by blocking the posttranscriptional synthesis of inducible nitric oxide synthase.

Cyclic AMP-elevating agents induce an inducible type of nitric oxide synthase in cultured vascular smooth muscle cells. Synergism with the induction elicited by inflammatory cytokines

In cultured vascular smooth muscle cells, interferon gamma (IFN-gamma) induced the accumulation of nitrite, a stable metabolite of nitric oxide, in a dose- and time-dependent manner. In parallel with this reaction, this cytokine increased the mRNA and protein levels of an inducible macrophage-type of nitric oxide synthase (iNOS). Forskolin, a direct activator of adenylate cyclase, or dibutyryl cAMP alone caused small increases in nitrite accumulation and iNOS mRNA and protein levels and synergistically enhanced the IFN-gamma-stimulated reactions. 8-Bromo-cGMP neither increased by itself nor synergized with IFN-gamma to increase the same reactions. Prostaglandin E1 and beraprost, a stable analogue of prostaglandin I2, which by themselves showed only marginal effects on these reactions, also synergized with IFN-gamma to stimulate the reactions. Interleukin 1 beta or tumor necrosis factor alpha stimulated the same reactions which were similarly enhanced by forskolin. These results indicate that an elevation of intracellular cAMP, particularly in combination with inflammatory cytokines, positively regulates nitric oxide production at the level of iNOS mRNA expression in vascular smooth muscle cells.