Pituitary Folliculo-Stellate-Like Cells Stimulate Somatotroic Pituitary Tumor Growth in Nude Mice

A new cell line (TtT/GF) established from a murine pituitary thyrotropic tumor having characteristics similar to those of pituitary folliculo-stellate cell (FS cell) was implanted into nude mice together with cells from a rat pituitary somatotrophic tumor cell line (MtT/S) to determine whether the former enhances pituitary tumor growth. For as long as 2-3 mo after implantation, MtT/S cells implanted either alone or together with fibroblasts formed either no tumors or only very small tumors in the nude mice. In contrast all of the nude mice that had received MtT/S cells implanted together with TtT/GF cells developed large tumors. Furthermore, the mice bearing the MtT/S and TtT/GF implants showed a significantly higher body weight and serum growth hormone level than those bearing only MtT/S cells or a combination of MtT/S cells and fibroblasts. The TtT/GF cell line itself had no tumorigenicity during the experimental period. Therefore, the TtT/GF cell line as a model of FS cells enhanced pituitary endocrine cell tumor formation. Additionally, immunocytochemistry showed that TtT/GF cells positive for glial fibrillary acidic protein (GFAP) or S-100 protein were present in the parenchymatous tissue elements or connective tissue surrounding the tumor nests. In the parenchymatous tissue, the TtT/GF cells exhibited a stellate appearance and surrounded neighboring tumor cells with their long cell processes. These results suggest that TtT/GF cells can serve as a model for pituitary FS cells, and are capable of stimulating pituitary tumor growth either by modifying the microenvironment or producing growth factors.     

Cross-linking of Fc(gamma)-receptor on monocytes inhibits hepatitis C virus-specific cytotoxic T-lymphocyte induction in vitro.

In hepatitis C virus (HCV) infection, immune complex (IC)-type virus particles are frequently observed in circulation. The IC leads to cross-linking of Fcgamma receptors (FcgammaR) on monocytes and exerts immunoinhibitory function. To test the roles of IC in HCV-specific cytotoxic T lymphocyte (CTL) induction, we generated HCV CTL from peripheral blood mononuclear cells of chronic hepatitis C patients with or without HCV-IC- or immunoglobulin G (IgG)-coated culture plates and compared their lytic activities. HCV-IC or adherent IgG, which induces FcgammaR cross-linking, significantly reduced CTL activity. Expression of B7-1 on monocytes decreased on adherent IgG. In addition, tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) production increased from cells on adherent IgG and their mRNA expression in monocytes was enhanced. Anti-TNF-alpha antibody during induction on adherent IgG inhibited lysis; however, anti-TGF-beta completely reversed its inhibitory effect. These results demonstrated that HCV-IC or adherent IgG impaired HCV-CTL induction in vitro. The FcgammaR-mediated CTL suppression occurred via decreased expression of monocyte B7-1 and/or enhanced production of TGF-beta1.     

Augmentation of human monocyte chemiluminescence by iron-saturated lactoferrin

The effect of Fe3+ bound lactoferrin (LF) on chemiluminescence (CL) generation in human monocytes in the presence and absence of opsonized zymosan was examined. Fe3+ bound LF (10(-6) or 10(-7) M) augmented the CL response in the presence but not the absence of zymosan. In contrast, Apo LF, Fe3+ bound transferrin and Fe3+ itself had no significant effect. It appears that the effect of LF on zymosan-induced chemiluminescence is dependent on iron and is receptor specific. The augmentation of CL by LF was inhibited by superoxide dismutase (SOD) and ETYA (fatty acid cyclooxygenase and lipoxygenase inhibitor), but not indomethacin (fatty acid cyclooxygenase inhibitor). Thus the enhancement of CL by LF depends on superoxide anion production and is related to the lipoxygenase pathway. The significance of this observation in terms of microbicidal or tumoricidal mechanisms remains to be determined.     

Enhancement of lipopolysaccharide-stimulated cyclooxygenase-2 mRNA expression and prostaglandin E2 production in gingival fibroblasts from individuals with Down syndrome

It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.     

Frozen-section services by telepathology: Experience of 100 cases in the San-in District, Japan

The early experience is reported here of the use of Intra-operative frozen-section service by telepathology using the Integrated Service Digital Network (ISDN), a commercially available system that is being connected between the Department of Pathology of Tottori University and Matsue City Hospital, a distance of 30 km. The transfer rate is currently 64kbit/s. The frozen-section service was conducted for a total of 117 tissue specimens (organs) from 100 patients between August 1993 and May 1995. The average time taken for examination of each specimen of frozen section was 13min, ranging between 2 and 42min. The average number of transmitted Images was 6.2. Six cases necessitated more than 11 transmitted Images to make a diagnosis, while 13 cases could be diagnosed from two images only. Correct and permissible diagnoses were obtained in 109 (93.2%) out of 117 specimens when comparing the telepathology diagnosis with that of direct microscopy. Improper or misdiag-nosis was made for eight cases (specimens), which were misinterpreted as papillary carcinoma in Basedow's disease, adenoma and hyperplasia in two pheochromocytomas, solid-tubular carcinoma in phyilodes tumor, mastopathy in invasive carcinoma, metastatic carcinoma in astrocytoma, follicular lymphoma in reactive hyperplasia, and lymphadenitis in follicular lymphoma. in retrospect, diagnosis of these cases should have been deferred. From the results, it was concluded that the Intraoperatlve frozen-section service by telepathology may be a worthwhile substitute for hospitals with limited accessibility to local pathology service, in spite of pitfalls in some cases. Well prepared, high-quality frozen sections, sufficient verbal communication with surgeons, and a rather conservative attitude on the part of a well-trained pathologist seem to be the essential Ingredients for reaching an accurate decision when using telepathology.     

Hemopoietic growth factors regulate the survival of human basophils in vitro.

Human basophils were purified from normal peripheral blood, using density gradient followed by negative panning selection. We tested the effects of hemopoietic growth factors on the survival of these basophils in vitro. In the absence of exogenous factors, basophils (purity greater than 90%) decreased in number rapidly. At day 7 only 11% of the cells remained alive in cultures; less than 1% of cells survived at day 14. Interleukin (IL)-3 maintained numbers of viable cells; cell viability was 67% at day 7 and 45% at day 14. Granulocyte-macrophage (GM)-colony-stimulating factor (CSF) exhibited slight effect on the survival; 33% of cells remained at day 7. Other growth factors including granulocyte (G)-CSF, macrophage (M)-CSF, and IL-4 had no significant effect on the survival of basophils at all. Morphological and functional characterization of cells maintained by IL-3 revealed that they belonged to the basophil lineage. These observations indicate that normal basophils possess functional receptors for IL-3 and GM-CSF and that both factors modulate immediate- and delayed-type hypersensitivity reactions by prolonging the life span of basophils.     

Membrane properties and inhibitory innervation of the circular muscle cells of guinea-pig caecum

1. The membrane properties of the circular muscle cells of guinea-pig caecum and nervous factors influencing the muscle activity were studied with micro-electrodes using partition and field stimulating methods.2. The mean membrane potential was -52 mV. Spontaneous discharges appeared as regular bursts between silent periods, as regular spikes without silent period, or as regular slow potential changes with superimposed spikes.3. Spontaneous spikes with overshoot were frequently observed. The mean maximum rate of rise was 5.2 V/sec. The mean conduction velocity of evoked spikes was 5.4 cm/sec.4. The amplitude of the elctrotonic potential was linearly proportional to the current applied by the partition stimulating method. The spatial decay of the electrotonic potential along the tissue was exponential, with a mean length constant of 1.7 mm.5. The time constants of the membrane calculated from the electrotonic potential, and from the conduction velocity, length constant and time course of the foot of the spike were about 200 and 100 msec respectively. These results indicate that the circular muscle of guinea-pig caecum possesses cable like properties.6. Field stimulation (0.3 msec pulse duration) to the circular muscle evoked three different responses successively, i.e. initial depolarization (initial excitatory junction potential) with or without spike, hyperpolarization (inhibitory junction potential) and delayed depolarization (delayed excitatory junction potential) with or without spikes.7. These three different potential changes were completely blocked by treatment with tetrodotoxin (5 x 10(-6) g/ml.), and both the initial and late excitatory junction potentials were blocked by treatment with atropine (5 x 10(-5) g/ml.).8. The distribution of inhibitory nerves in the circular muscle cells was investigated. The results indicate that inhibitory nerves arise from Auerbach's plexus situated just beneath the taenia coli and the nerve branches spread over the whole distance from one taenia coli to the next along the ciruclar muscle cells, a width of about 3 mm.9. The mean conduction velocity of excitation of the inhibitory nerves was 16.0 cm/sec. Hexamethonium, in a concentration of 5 x 10(-6) g/ml. depolarized the circular muscle membrane and lowered the rate of rise and fall of spike, but did not block the generation of inhibitory junction potentials.     

Bone bonding behavior of three kinds of apatite containing glass ceramics

We have produced three kinds of apatite-containing glass ceramics of the same chemical composition: MgO (4.6), CaO (44.9), SiO2 (34.2), P2O5 (16.3), CaF2 (0.5) (in weight ratio). They contain different crystal combinations and have different mechanical properties. The first glass ceramic (A-GC) was prepared by heating a glass plate to 870 degrees C. It contains only oxy- and fluoroapatite (35 wt%). The second glass ceramic (A-W-GC), and the third (A-W-CP-GC), were prepared by heating glass powder compacts to 1050 degrees C and 1200 degrees C, respectively. A-W-GC contains oxyapatite and fluoroapatite (Ca10(PO4)6(O,F2] (35 wt%) and beta-wollastonite (40 wt%). A-W-CP-GC contains oxyapatite and fluoroapatite (20 wt%), beta-wollastonite (CaO X SiO2) (55 wt%), and beta-whitlockite (3CaO X P2O5) (15 wt%). The bending strengths of A-GC, A-W-GC, and A-W-CP-GC were 88MPa, 178MPa, and 213MPa, respectively, in air. Rectangular ceramic plates (15mm X 10mm X 2mm) were implanted into a rabbit tibia. Ten and 25 weeks after implantation, the segment of tibia with implant was excised for examination. The segment was held by a special jig and the traction breaking load (failure load) was measured by an autograph. A-GC showed a lower load than A-W-GC and A-W-CP-GC. The loads for A-W-GC and A-W-CP-GC were almost equal. The failure loads did not change significantly between 10 and 25 weeks for any of the materials. The interface was examined by Giemsa surface staining, contact micro-radiography, and SEM-EPMA. Giemsa surface staining and CMR revealed direct bonding between the materials and the bone for all the three materials. SEM-EPMA showed that Si and Mg content decreased, Ca content did not change, and P content increased at the reaction zone between all three glass ceramics and bone. This was observed at 10 weeks, as well as at 25 weeks, after implantation. The reaction zone was narrowest with A-GC, wider with A-W-GC, and widest with A-W-CP-GC.