Growth factor-dependent regulation of transferrin receptor in proliferating and quiescent macrophages

Transferrin receptor (TfR) expression in a population of murine macrophages was investigated during the colony-stimulating factor-1 (CSF-1)-induced proliferation and quiescence. Depletion of CSF-1 from the culture medium of bone marrow cell-derived macrophages (BMM) resulted in a simultaneous decrease in the total (cell surface + intracellular) amount of TfR and complete cessation of proliferating activity [( 3H]thymidine incorporation). The addition of CSF-1 to quiescent BMM resulted in a bimodal increase in surface TfR activity. A rapid but transient twofold increase only on the cell surface due to changes in the cycling of TfR was followed by a steady increase of total cellular TfR due to de novo synthesis. A similar transient increase in surface TfR was also induced by another hemopoietic colony-stimulating factor, GM-CSF, which is mitogenic for BMM. IL-3, which did not stimulate the clonal growth of these cells, failed to modulate surface TfR. In contrast to its effect on the cycling rate of TfR in quiescent cells, CSF-1 had little effect on the TfR distribution on proliferating BMM as well as on the J774 cells (a macrophage-like tumor cell line) despite the latter expressing high levels of CSF-1 receptor. This study showed that (i) cell surface modulation by growth factor is a function of state of cellular proliferation, and (ii) rapid changes in the cell surface distribution of TfR result from changes in its cycling rates.

Non-peptide angiotensin II receptor antagonists discriminate subtypes of 125I-angiotensin II binding sites in the rat brain

We have utilized quantitative autoradiography to define subtypes of 125I-angiotensin II (AII) binding in rat brain. AII-1 binding (displaced by DuP 753) was found in the nucleus of the solitary tract and the hypothalamus, while AII-2 binding (displaced by WL 19) was found in the thalamus and lateral septum. These results indicate that subtypes of the AII receptor are present in the brain and the AII-1 receptor subtype is present in regions consistant with the known actions of angiotensin.

The treatment of progressive non-Hodgkin's lymphoma with intensive chemoradiotherapy and autologous marrow transplantation

Intensive chemoradiotherapy, with or without additional local radiotherapy, and unpurged autologous marrow transplantation was given to 68 patients with progressive non-Hodgkin's lymphoma. Responses were attained in 44 patients (65%, 95% confidence intervals [CI], 52% to 76%), including 37 who achieved complete responses. Fifteen patients (22%, 95% C.I. 13% to 34%) remain free of disease (including 11 continuously) at a median of 5.3 (range 3.1 to 9.1) years later. Higher Karnofsky scores (P less than .01, Mann-Whitney U test) and the absence of a history of prior radiotherapy (P = .02, chi 2 test) were associated with achievement of complete plus partial responses. Higher Karnofsky scores (P less than .01, Mann-Whitney U test) and less resistant disease status at transplantation (P = .04, chi 2 test) were significant when calculations were limited to complete responses. Karnofsky scores were also associated with the probability of freedom from progression (P = .02, log-rank) for responding patients. Also, Karnofsky scores and the absence of prior radiotherapy (P less than .01 and P = .01, respectively, log-rank) were associated with improved survival. Progressive lymphoma was the chief cause of failure; progression usually occurred less than 6 months after transplantation, most often at the sites of active disease before the transplant. However, five patients (including four with high-grade non-Hodgkin's lymphoma) suffered hematogenous patterns of relapse; four of these five patients had no prior history of marrow involvement. Other causes of mortality included interstitial pneumonitis, sepsis, hemorrhage and renal failure. Intensive chemoradiotherapy and autologous marrow transplantation produces durable remissions in some patients with progressive non-Hodgkin's lymphoma. Since such therapy is more effective when given to patients with signs of less advanced disease, earlier treatment would be the simplest way to produce improved results. However, improved conditioning regimens will also be needed, and measures to reduce occult lymphoma stem cell contamination with the autograft may also be required to increase the likelihood of cure in some patients.

Comparison of the inhibitory effect of polyunsaturated fatty acids on prostaglandin synthesis. II. Fibroblasts

In a previous publication we reported that PUFAs of the n-6 and n-3 series caused significant inhibition of synthesis of both PGE2 (28.4-92.8%) and PGF2 alpha (24.4-84.0%) in the oral squamous carcinoma cell line SCC-25. In this report we describe the inhibitory effect of the same acids on PG synthesis in normal human gingival fibroblasts under the same experimental conditions. It was found that a combination of EPA + DCHA (6:4), DCHA and ALA caused significant reduction in synthesis of PGE2 (10.1-87.8%) and PGF2 alpha (14.0-54.6%) at the four dose levels studied. The rank order of potency of acids in reduction of PG synthesis was: EPA + DCHA greater than DCHA greater than EPA greater than ALA greater than LA greater than DGLA greater than GLA. The data suggest that although PUFAs are effective inhibitors of PG synthesis by gingival fibroblasts and SCC-25, the fibroblast is less susceptible to the inhibitory effect of fatty acids.

Comparison of the inhibitory effect of polyunsaturated fatty acids on prostaglandin synthesis I oral squamous carcinoma cells

Polyunsaturated fatty acids (PUFAs) have been shown to suppress the growth rate of human osteogenic sarcoma cells and to have selective cytotoxic activity against human cancer cells. The purpose of this study was to investigate the efficacy of various PUFAs on inhibition of prostaglandin (PG) synthesis by oral squamous carcinoma cells (SCC-25). A significant inhibition of PGE2 and PGF2 alpha synthesis in SCC-25 was observed by all PUFAs tested except in the case of linoleic acid (LA) at 10 microM level. At 10 microM level the rank order of inhibition of PG synthesis by PUFAs was docosahexaenoic (DHA) greater than eicosapentaenoic (EPA) + DHA greater than dihomogamma-linolenic (DGLA) greater than EPA greater than alpha-linolenic (ALA) greater than linoleic (LA). At 50, 75, 100 microM the rank order of inhibition was DGLA greater than EPA greater than EPA + DHA greater than DHA greater than ALA greater than LA.

Regulation of systemic macrophage IL-1 gene transcription: the involvement of tumor-derived macrophage growth factor, CSF-1

Previous data indicated that progressive growth of the C57BL/6J sarcoma, MCA/76-9, was associated with a systemic increase in the level of IL-1 activity in peritoneal and tumor-associated macrophages. In this paper, the hypothesis was tested that macrophage IL-1 alpha and beta gene expression was regulated by the specific macrophage growth factor, CSF-1, produced by tumor cells. The data indicated that all of the nine C57BL/6J, BALB/cJ, and C3H/HeJ sarcomas tested transcribed the CSF-1 gene. The tumor cell culture supernates induced proliferation of bone marrow cells that differentiated into macrophages. Moreover, proliferative activity of conditioned medium and the ability to induce macrophage differentiation were abrograted by neutralization with the 5A1, rat-anti-mouse monoclonal anti-CSF-1 antibody. Conditioned medium from tumor cell cultures, as well as recombinant CSF-1 and L cell-conditioned medium, induced transcription of the IL-1 alpha and beta genes, the latter being more strongly expressed. IL-1 gene transcription was not induced after neutralization of the culture supernates by the monoclonal antibody, 5A1. The overall data would support the hypothesis that the pathway in vivo leading to the increased IL-1 expression by macrophages is regulated by at least one tumor cell product, CSF-1.

A sandwich enzyme-linked immunoadsorbent assay for detection of murine macrophage colony-stimulating factor (CSF-1)

A simple three-layer sandwich enzyme-linked immunoadsorbent assay (sandwich-ELISA) has been developed for murine macrophage colony-stimulating factor-1 (CSF-1) using the two monoclonal antibodies on which we recently reported (J. Immunol. (1988) 141, 483). The anti-CSF-1 monoclonal antibodies used in this assay recognize different epitopes of the same antigen, thereby permitting the detection of low amounts of CSF-1. This assay is specific to murine CSF-1. Recombinant human macrophage colony-stimulating factor, murine GM-CSF, or IL-3, either alone or together with CSF-1, does not interfere with the assay. The advantage of this assay over other reported immunoassays for CSF-1 is that radiolabeled or large quantities of purified CSF-1 are not required. This sandwich-ELISA compares favorably with other assays in its rapidity, simplicity, and sensitivity.

Treatment of progressive Hodgkin's disease with intensive chemoradiotherapy and autologous bone marrow transplantation

Twenty-six patients with progressive Hodgkin's disease after conventional chemotherapy received intensive chemoradiotherapy and autologous bone marrow transplantation (ABMT); 19 also received additional involved-field radiotherapy. Twenty-one patients [81%, 95% confidence intervals (CI) 61% to 94%] attained complete (n = 18) or partial responses. Ten patients (38%, 95% CI 20% to 59%) are disease-free a median of 4.5 years later (range 3.5 to 7.0 years), including seven patients with continuous complete responses. The likelihood of overall response was not significantly influenced by any clinical or treatment variable examined. However, there was a trend favoring patients with higher Karnofsky scores, and higher scores were associated with attainment of complete responses (P = .06 and P = .02, respectively, Mann-Whitney U test). Both higher Karnofsky scores and shorter durations of disease before transplantation were associated with improved survival in a stepwise Cox multivariate analysis. The chief cause of failure was progression at sites previously involved with Hodgkin's disease. No patient relapsed in the marrow, and two of three patients with a history of marrow involvement with Hodgkin's disease achieved durable complete responses after transplantation. These data suggest that inadequate pretransplant conditioning, and not the reinoculation of occult tumor cells in the autologous marrow, caused most relapses. Fatal treatment-related toxicity occurred in six patients. Three patients died of idiopathic interstitial pneumonitis; each had previously received local mediastinal irradiation before intensive chemoradiotherapy. Intensive chemoradiotherapy and ABMT produces durable responses in some patients with Hodgkin's disease incurable with conventional therapy. Use of such therapies at the first sign of failure with conventional chemotherapy and development of more effective conditioning regimens should further improve results.

Purification and characterization of a benzodiazepine-like substance from mammalian brain

An endogenous brain ligand which competes with [3H]-flunitrazepam for the binding to benzodiazepine receptor has been isolated and purified to homogeneity. The purification procedures involve the extraction of the endogenous ligand by homogenizing the brain tissue in water containing various protease inhibitors followed by filtration through a PM 10 membrane (exclusion limit: 10,000-dalton), column chromatographies on Sephadex G-50, Bio-Rad P2 and a series of C18 reverse phase HPLC columns. The purified endogenous ligand was eluted as a single and symmetrical peak monitored at either 220 or 280 nm. Furthermore, the ligand activity coincided with the absorption peak. The purified endogenous ligand is thermostable, insensitive to various peptidases and proteolytic enzymes, resistant to DNAse, RNAse, and carbohydrate enzyme e.g. neuraminidase (EC 3.2.1.18) and acid treatment. It has a major absorption peak at 220 nm and a minor one at 313 nm. The endogenous ligand appears to be quite specific since it only inhibits the binding of ligand to the central type benzodiazepine receptor but not to other receptors, e.g. peripheral type benzodiazepine receptor, alpha 1-adrenoceptor, alpha 2-adrenoceptor, beta-adrenoceptor and muscarinic cholinergic receptor. Furthermore, the inhibition of the receptor binding by the endogenous ligand is enhanced by GABA suggesting that the endogenous ligand is a benzodiazepine receptor agonist. The structure of the endogenous ligand is unknown.

Both granulocyte-macrophage CSF and macrophage CSF control the proliferation and survival of the same subset of alveolar macrophages

The effect of granulocyte-macrophage (GM)-CSF on the proliferation of murine pulmonary alveolar macrophages in vitro was investigated. About 20% of freshly isolated alveolar macrophages formed colonies in both liquid and soft agar cultures in the presence of GM-CSF. GM-CSF was also found to be capable of maintaining the survival of these colony-forming cells in vitro. Moreover, GM-CSF could substitute for CSF-1 in maintaining the survival of CSF-1-responding pulmonary alveolar macrophage colony-forming cells in the absence of CSF-1. The concentration of GM-CSF required for maintaining the survival of colony-forming cells without proliferation was much lower than that required for the proliferation of these cells in vitro. It also enhanced the CSF-1-dependent clonal growth of alveolar macrophages. These data suggest that the colony-forming cells that respond to GM-CSF are the same subset of macrophages that form colonies in the presence of CSF-1. GM-CSF did not inhibit the binding of 125I-CSF-1 to alveolar macrophages at 0 degrees C. However, the preincubation of macrophages with GM-CSF at 37 degrees C resulted in a transient down-regulation of CSF-1 binding activity.

Both granulocyte-macrophage CSF and macrophage CSF control the proliferation and survival of the same subset of alveolar macrophages

The effect of granulocyte-macrophage (GM)-CSF on the proliferation of murine pulmonary alveolar macrophages in vitro was investigated. About 20% of freshly isolated alveolar macrophages formed colonies in both liquid and soft agar cultures in the presence of GM-CSF. GM-CSF was also found to be capable of maintaining the survival of these colony-forming cells in vitro. Moreover, GM-CSF could substitute for CSF-1 in maintaining the survival of CSF-1-responding pulmonary alveolar macrophage colony-forming cells in the absence of CSF-1. The concentration of GM-CSF required for maintaining the survival of colony-forming cells without proliferation was much lower than that required for the proliferation of these cells in vitro. It also enhanced the CSF-1-dependent clonal growth of alveolar macrophages. These data suggest that the colony-forming cells that respond to GM-CSF are the same subset of macrophages that form colonies in the presence of CSF-1. GM-CSF did not inhibit the binding of 125I-CSF-1 to alveolar macrophages at 0 degrees C. However, the preincubation of macrophages with GM-CSF at 37 degrees C resulted in a transient down-regulation of CSF-1 binding activity.

Unusual ultrastructural features in the superficial pineal gland of the yellow-bellied country rat (Rattus losea Swinhoe)

The ultrastructure of the superficial pineal gland of the yellow-bellied country rat (Rattus losea Swinhoe), living under natural climatic conditions at the margin of the tropical region, was studied with special reference to the seasonal changes. In the rainy season with average monthly rainfall of 400 mm (light phase of 13.5 h, and temperature of 28 degrees C) the gland was characterized by the presence of frequent large vacuoles containing flocculent material (LVFs), large condensed inclusions (LCIs) in the pinealocytes, and extensive accumulations of presumptive secretion in the extracellular compartment, suggesting an enhanced secretory activity. In the dry season with average monthly rainfall of 13 mm (light phase of 11 h, and temperature of 19 degrees C), however, the pinealocytes were characterized by the presence of numerous clear spindles, which exhibited acid phosphatase activity; at this time there were few LVFs and LCIs and rare extracellular accumulations, suggesting a declined glandular activity. We conclude that the cellular activity of the pineal gland in R. losea, living under tropical climatic conditions, is synchronized with the annual changes of rainfall, which is apparently more important than the annual changes of photoperiod and temperature.

Biochemical mechanisms underlying the development of radioresistance by cultured peritoneal exudate macrophages

We investigated changes in radiosensitivity of peritoneal exudate macrophage colony-forming cells (PE-CFC) when exudative peritoneal macrophages were cultured in vitro. The change in the shape of the dose-response curve of PE-CFC to ionizing irradiation was partly dependent on the concentration of oxygen in the gas phase of the incubators. When cells were incubated in an environment containing 20% oxygen, the value of both Dq and D0 for PE-CFC increased. The dose-response curve of PE-CFC cultured for 3 days resembled that of alveolar macrophage colony-forming cells (AL-CFC). The changes in radiosensitivity were accompanied by an increase in the level of three antioxidant enzymes: superoxide dismutase, catalase, and glutathione peroxidase. However, when they were cultured in a 6% oxygen environment, only the value of Dq increased. When alveolar macrophages were incubated in vitro, no significant change in the shape of the dose-response curve of AL-CFC was noted whether they were cultured in gas phase containing either 20 or 6% oxygen. It is concluded that the radiosensitivity of PE-CFC changes when they are cultured in vitro. The increase in D0 appears to be related to the intracellular level of antioxidant enzymes.

Development and characterization of monoclonal antibodies to murine macrophage colony-stimulating factor

The macrophage-specific CSF (CSF-1), purified from murine L cell-conditioned medium, supports the in vitro proliferation and survival of various murine mononuclear phagocyte colony-forming cells. In this report we describe the production and functional characterization of two monoclonal antibodies (mAb) to CSF-1 obtained from rat X rat hybridomas. These two mAb are functionally distinct and recognize different epitopes on CSF-1. The mAb 5A1 binds to and inhibits the biologic function of CSF-1, and the second mAb (D24) binds CSF-1 but does not neutralize its biologic activity. The mAb 5A1 inhibits colony formation of tissue mononuclear phagocyte colony-forming cells as well as the committed bone marrow stem cells for both granulocytes and monocytes. The extent of colony inhibition by mAb 5A1 is dependent on the tissue origin of colony-forming cells. CSF-1 complexed with mAb 5A1 does not bind to its cell surface receptor of peritoneal exudate macrophages, and mAb 5A1 does not complex with cell-bound CSF-1. Although both bone marrow cell-derived macrophages and J774.1 macrophages bind CSF-1, mAb 5A1 inhibits the proliferation of only bone marrow cell-derived macrophages. The non-neutralizing mAb D24 does not block binding of CSF-1 to its cellular receptor, and it recognizes cell-bound CSF-1.

Development and characterization of monoclonal antibodies to murine macrophage colony-stimulating factor

The macrophage-specific CSF (CSF-1), purified from murine L cell-conditioned medium, supports the in vitro proliferation and survival of various murine mononuclear phagocyte colony-forming cells. In this report we describe the production and functional characterization of two monoclonal antibodies (mAb) to CSF-1 obtained from rat X rat hybridomas. These two mAb are functionally distinct and recognize different epitopes on CSF-1. The mAb 5A1 binds to and inhibits the biologic function of CSF-1, and the second mAb (D24) binds CSF-1 but does not neutralize its biologic activity. The mAb 5A1 inhibits colony formation of tissue mononuclear phagocyte colony-forming cells as well as the committed bone marrow stem cells for both granulocytes and monocytes. The extent of colony inhibition by mAb 5A1 is dependent on the tissue origin of colony-forming cells. CSF-1 complexed with mAb 5A1 does not bind to its cell surface receptor of peritoneal exudate macrophages, and mAb 5A1 does not complex with cell-bound CSF-1. Although both bone marrow cell-derived macrophages and J774.1 macrophages bind CSF-1, mAb 5A1 inhibits the proliferation of only bone marrow cell-derived macrophages. The non-neutralizing mAb D24 does not block binding of CSF-1 to its cellular receptor, and it recognizes cell-bound CSF-1.

Self-renewal of pulmonary alveolar macrophages: evidence from radiation chimera studies

Radiation-induced chimeric mice were used to study the origin of pulmonary alveolar macrophages. Unlike in other studies, these radiation chimeras were prepared by using a special fractionated irradiation regimen to minimize the killing of alveolar macrophage colony-forming cells, putative local stem cells. For this study CBA mice with or without T6 chromosome marker were used. Under this experimental condition, the majority of alveolar macrophages in mitosis are of host origin even after 45 weeks. These data suggest that alveolar macrophages are a self-renewing population under normal steady-state conditions.

Prostaglandin synthesis by squamous carcinoma cells of head and neck, and its inhibition by non-steroidal anti-inflammatory drugs

The purpose of this study was to determine the nature and amounts of prostaglandins (PGs) produced by squamous carcinoma cells (SCC) and the sensitivity of these cells to non-steroidal anti-inflammatory drugs. SCC of four lines of the tongue and one line of facial epidermis of humans were incubated in phosphate buffer solution with 14C-arachidonic acid (AA). Radioactive metabolites in aqueous methanol were chromatographed on Sep-Pack C18 cartridges, separated and quantitated by means of TLC, autoradiography, and liquid scintillation counting. The results showed that cyclooxygenase products, PGs, were the major products formed by all cell lines, and PGE2 was predominant among the PGs detected. Two radioactive bands corresponding to PGF2 alpha and three unseparated standards of PGA2, 15-keto-PGE2, and 13,14-dihydro-15-keto-PGE2 were detected in lesser amounts. Very small amounts of the lipoxygenase products 12- and 15-HETE were found. The concentrations of indomethacin, ibuprofen and aspirin required to inhibit 50% of PGE2 synthesis (IC50) by SCC lines were .008-.080, .080-6.4 and 32-88 microM, respectively.

Effect of effervescent buffered aspirin on prostaglandin synthesis by human gingival fibroblasts

Cultured human gingival fibroblasts were incubated with 14C-arachidonic acid (AA) at 37 degrees C for 2 hours. The metabolites formed were extracted from the cell-free medium in methanol, separated and identified by thin layer chromatography, using two solvent systems that allowed resolution of cyclooxygenase and lipoxygenase products. The predominant cyclooxygenase products were PGE2 and 6-keto-PGF1 alpha. PGA2, PGF2 alpha, PGD2, 15-keto-PGE2, TXB2 were also detected in smaller amounts. No detectable radioactivity corresponding to lipoxygenase products 5-HETE, 12-HETE, and 15-HETE was found. Incubation of fibroblasts with effervescent buffered aspirin (EBA) (.02%, .04%, .06%), or sodium bicarbonate, citric acid and aspirin, individually, (in concentrations equivalent to those present in EBA) resulted in stimulation of synthesis of PGs except PGE2 which was inhibited by EBA and aspirin.

Three dimensional visualization of the Golgi apparatus and endoplasmic reticulum in the subcommissural organ cells with high voltage electron microscopy

Fine structure and stereo-images of the Golgi apparatus and endoplasmic reticulum (ER) in the subcommissural organ (SCO) cells were visualized by the application of zinc-iodide osmium tetroxide (ZIO) impregnation, conventional electron microscopy and high voltage electron microscopy (HVEM). The Golgi apparatus in the SCO cells of rats, gerbils and hamsters consisted of flattened saccules stacked in parallel array. It showed a selective staining toward ZIO mixture and might form a complex network of tubular structures because of the presence of numerous fenestrations in the flattened Golgi saccules. The cytoplasm of the SCO cells in the rat and gerbil was crowded by dilated cisternae of the ER with a few flattened profiles. In the hamster SCO cells, however, the dilated cisternae of the ER were not observed. Flattened cisternae of ER in all species studied showed a positivity for ZIO impregnation and formed a complex tubular network, whereas dilated cisternae of the ER in the rats and gerbils did not show any reactivity. It was thus determined that the observation of thin and thick sections selectively stained with appropriate reagent for defined cellular organelles under conventional electron microscopy and HVEM offered valuable information about three-dimensional organization of the cell. A definite species-specific variation of SCO ultrastructure and cytochemistry was also demonstrated.

Immunocytochemical identification of growth hormone cells in the adenohypophysis of the golden hamster

Somatotrophs or growth hormone (GH) cells in the adenohypophysis of golden hamsters were identified by immunocytochemical staining with polyclonal rabbit anti-human GH. They were oval or columnar in shape, and had secretory granules of two size ranges, 90-150 nm and 280-320 nm, which were present in the same cells; no subtypes of GH cells were observed. Secretory granules were located in the peripheral portion of the cytoplasm or concentrated at the vascular pole of the cell. Flattened cisternae of the rough endoplasmic reticulum in parallel array and a moderately developed Golgi apparatus were often found in the cytoplasm. No sex difference was noticed in the population ratio of GH cells. Immunocytochemical staining with anti-GH or anti-prolactin (PRL) antibodies on separate adjacent sections revealed that the GH and PRL were stored in two different cell types.

Fine structural and cytochemical studies on the hamster subcommissural organ

The subcommissural organ (SCO) of the golden hamster (Mesocricetus auratus) was studied by conventional electron microscopy, freeze-fracture technique, zinc-iodide-osmium (ZIO) and acid phosphatase cytochemical reactions. The ultrastructure of hamster SCO cells shows a few flattened cisternae of rough endoplasmic reticulum (ER) without dilated ones in the cytoplasm. The Golgi apparatus is very well developed. Freeze-fracture studies also indicate only short profiles of flattened ER in the cytoplasm endorsing the absence of dilated ER cisternae. After the treatment with ZIO mixture, reaction products were observed over flattened cisternae of the ER and the nuclear envelope. The Golgi apparatus was also reactive toward the ZIO mixture. Acid phosphatase activities are localized in the inner one or two saccules of the Golgi apparatus and dense bodies. From these results we suggest that (1) hamster SCO cells do not accumulate secretory material in the cytoplasm in the form of discrete secretory granules or dilated cisternae of ER, and (2) hamster SCO cells may possess extremely high secretory activity or may not be actively involved in secretory function at all as in rats or other rodents.

A centrosomal inclusion (striped nebulous body) in pinealocytes of the golden hamster

Electron microscopy has revealed the presence of a special cytoplasmic body in the centrosomal area of pinealocytes of the golden hamster, Mesocricetus auratus. It consists of branching electron-dense ribbons embedded in a flocculent matrix of moderate electron density, and is tentatively named the 'striped nebulous body' (SNB). The dense ribbon usually appears as a thick band accompanied by a parallel thin one to one side. The SNB is not bounded by a membrane, and is roughly round or kidney-shaped. Closely associated with the SNB are centrioles, microtubular sheaves and striated fibrils, the latter two being centriolar derivatives. The observations suggest that the SNB might be formed by the amalgamation of these microtubular sheaves and striated fibrils. In golden hamsters, pinealocytes often have multiple centrioles and centriolar derivatives. The SNB of adult hamsters is seen in the pinealocytes of both sexes, irrespective of the season of the year and the activity of the pineal gland. The functional significance of this body remains to be studied.

Immunocytochemical studies on prolactin cells in the adenohypophysis of the golden hamster

Mammotrophs or prolactin (PRL) cells were identified in the adenohypophysis of adult golden hamsters by immunocytochemical techniques with a polyclonal anti-PRL, that was proved to be specific to PRL by the dot immunoblotting test. Postembedding immunostaining was performed on Araldite thin sections by immunoperoxidase and immunogold methods. PRL cells were classified into three types according to the different size of the secretory granules. The Type A cells were usually small and angular or oval in shape, and had secretory granules ranging in diameter from 100-230 nm, and showed poorly developed organelles. The Type B and C cells were larger and round or ovoid in shape, contained larger granules, 230-280 nm and 280-570 nm, respectively, and displayed well developed organelles. Immunoreactive PRL cells in the male pituitaries were far less numerous than in the nonpregnant female glands, and were mostly of the Type A and B, whereas in the female the Type C and B cells predominated. In pregnant females, Type C cells became activated and increased in number, while the other two types decreased in proportion. In lactating females, Type A and B cells significantly increased in number at the expense of the Type C cells; meanwhile, the exocytosis of secretory granules was frequently found in all types of PRL cells. The present findings suggest that Type C and B PRL cells, especially the former, are potent in producing and releasing PRL and highly responsive to various physiological stimuli, while Type A cells are probably relatively inert in synthetic activity.

Brain L-glutamate decarboxylase: purification and subunit structure

Glutamate decarboxylase (GDCase; L-glutamate-1-carboxy-lyase, EC 4.1.1.15) was purified from whole rat brain approximately equal to 1300-fold to apparent homogeneity with a specific activity of 2.4 units per mg of protein by a combination of column chromatographies on DEAE-cellulose, hydroxylapatite, and gel filtration, and preparative nondenaturing polyacrylamide gel electrophoresis. The purified preparation contained a single protein band that comigrated with GDCase activity in three diverse analyses: nondenaturing regular (5%) and gradient (3.6-25%) polyacrylamide gel electrophoresis and isoelectric focusing at pH 4-7. The native molecular mass was calculated to be 120 +/- 10 kDa from gradient polyacrylamide gel electrophoresis and 110 +/- 10 kDa from gel filtration. Under the treatment with NaDodSO4 and 2-mercaptoethanol, GDCase dissociated into two subunits of 40 +/- 2 and 80 +/- 4 kDa, as estimated from NaDodSO4 gel electrophoresis. However, only a 40-kDa subunit was detected when GDCase was treated with 4 M urea plus NaDodSO4 and 2-mercaptoethanol, suggesting that the 80-kDa subunit is the dimer of the 40-kDa subunit. In immunoblotting, polyclonal antibodies against GDCase reacted with both 40- and 80-kDa subunits, while monoclonal antibody reacted with only 80-kDa subunits. The isoelectric point of the native enzyme was 5.4. The Km for glutamate was 1.59 X 10(-3) M. In addition to L-glutamate, cysteine sulfinic acid was also decarboxylated at approximately equal to 10% of the rate of glutamate. The pH optimum was fairly broad, with a maximum at approximately equal to 7.3. The enzyme was strongly inhibited by carbonyl-trapping agents, sulfhydryl reagents, thiol compounds, and beta-methylene-DL-aspartate.