Inhibition of hepatic metastasis of colon carcinoma by asialo GM1--positive cells in the liver

This study investigates the role of hepatic asialo GM1-positive cells in inhibiting hepatic metastasis of colon carcinoma (colon adenocarcinoma 38) in mice after administration of a biological response modifier, streptococcal derivative (OK432). Administration of OK432 increased the number of asialo GM1-positive cells in the liver, enhanced natural killer activity of hepatic mononuclear cells and reduced the number of hepatic metastases of colon carcinoma inoculated into the superior mesenteric vein. Administration of antiserum against asialo GM1 reduced the number of hepatic asialo GM1-positive cells, abolished natural killer activity of hepatic mononuclear cells and increased the number of hepatic metastases. In addition, administration of antiserum against asialo GM1 even after OK432 treatment also decreased the number of asialo GM1-positive cells, reduced natural killer activity of hepatic mononuclear cells and increased the number of hepatic metastases of colon carcinoma. However, administration of gadolinium chloride, which suppresses phagocytic function of Kupffer cells, did not influence the natural killer activity of hepatic mononuclear cells or the number of hepatic metastases. In vivo tumor-neutralization assay revealed that tumor growth was inhibited by the hepatic mononuclear asialo GM1-positive cells, but not by T lymphocytes or Kupffer cells after OK432 administration. These results suggest that an increased number of hepatic asialo GM1-positive cells after administration of OK432 plays an important role in protecting against metastasis of colon carcinoma in the liver.

[Influence of affect on everyday memory: self-reference of retrieval cue]

There have been two views as to mood congruent recall: The one interprets it as an automatic process, while the other explains that it appears only when self-referent information processing is running. In this study, one experiment was conducted in order to examine these two opposing views. By false feedback of task performance, positive or negative mood had been induced in each subject, who was given two "cue" words, and asked to retrieve everyday events. The result was that mood congruent recall occurred when the word "self" was presented as a cue; but no effect of mood with neutral cues. This result supports the hypothesis that mood congruent recall is found only when self-referent information is processed. However, such effect was not evident in positive mood condition. In positive mood condition, there remains a possibility that mood congruent recall may be an automatic process. The effects of mood on memory were discussed from various viewpoints.

Spatial organization of the auditory nerve according to spontaneous discharge rate

Auditory-nerve fibers in mammals have been classified into three functional subclasses according to spontaneous discharge rate (SR). In cat, the peripheral terminals of these SR groups are segregated around the sensory cell circumference (Liberman, '82, Science 216:1239-1241). The present study shows that this spatial segregation is at least partly maintained through the peripheral axonal course from sensory cell to spiral ganglion. Analysis of intracellularly labeled auditory-nerve fibers shows that peripheral axons and cell bodies of low- and medium-SR fibers tend to be found closer to scala vestibuli than high-SR fibers. Since low- and medium-SR fibers tend to be thinner, this SR-based segregation can also be demonstrated as a fiber-caliber gradient in the osseous spiral lamina. The issue of SR-based spatial segregation is relevant to reports that ganglion cells near scala vestibuli project to different regions of the cochlear nucleus than cells near scala tympani (Leake and Snyder, '89, J. Comp. Neurol. 281:612-629). Combining the results of the two studies suggests that there may be some SR-based spatial segregation of inputs to the cochlear nucleus.

Aluminum fluoride induces a reversible Ca2+ sensitization in alpha-toxin-permeabilized vascular smooth muscle

The mechanism of aluminumfloride (AlF)-induced Ca2+ sensitization was explored in alpha-toxin-permeabilized rabbit mesenteric artery. In the presence of 0.18 microM Ca2+ and deferoxamine, a strong chelator of aluminum (Al3+), fluoride (F-; applied in the form of NaF) induced very slow tension development, while in the presence of tracer levels of Al3+ tension developed rapidly possibly due to formation of Al-F complexes (especially AlF4-). As a result, AlF significantly shifted the relationship between tension development and free Ca2+ concentration in the Ca(2+)-EGTA buffer (pCa-tension curve) to the left. The rate of the tension development also depended on the EGTA concentration: increasing the EGTA concentration from 0.5 to 10 mM markedly decreased the maximal rate of contraction ((dT/dt)max), probably due to chelation of Al3+ by EGTA, without effect on the maximal tension (delta Tmax). The AlF-induced Ca2+ sensitization could be reversed by extensive washing with relaxing solution (pCa greater than 8), in contrast to the contractions induced by guanosine 5'-[gamma-thio]triphosphate (GTP gamma s; a non-hydrolyzable GTP analogue) or phorbol 12,13-dibutyrate (PDBu) which were irreversible. However, the action of all the compounds appeared to be mediated through a H-7 (1-[5-isoquinolinesulfonyl]-2-methylpiperazine dihydrochloride)-sensitive pathway, and no additive effects among them were observed. In addition, GDP increased (dT/dt)max due to AlF without changing delta Tmax, whereas guanosine 5'-[beta-thio]diphosphate (GDP beta s; a non-hydolyzable GDP analogue) decreased both parameters. These findings suggest that AlF acts on G-proteins to enhance Ca2+ sensitivity of contractile elements through a H-7-sensitive pathway.

Cholestatic hepatocellular carcinoma diagnosed by deposits of Lipiodol and treated by combination of endoscopic retrograde biliary drainage and transcatheter arterial embolization

Cholestatic hepatocellular carcinoma, which grows into the bile duct and causes obstructive jaundice, is rare and difficult to diagnose. A case is presented in which cholestatic hepatocellular carcinoma was detected by deposit of Lipiodol. This is also the first case that was successfully treated by endoscopic retrograde biliary drainage and transcatheter arterial embolization.

Effect of phorbol myristate acetate on release of arachidonic acid and its metabolites in the osteoblastic MOB 3-4 cell line and its subclone, MOB 3-4-F2

We examined the effect of phorbol 12-myristate 13-acetate (PMA) on release of arachidonic acid (AA) and its metabolites in osteoblastic cells in an attempt to study mechanism of the regulation of phospholipase A2 (PLA2) activity. In the MOB 3-4-F2 cell line, a subclone of the clonal osteoblastic MOB 3-4 cell line, PMA (0.1-100 nM) changed its appearance and increased AA release in a dose- and time-dependent manner, whereas 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD) did not show a significant affect on the release. The addition of 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, greater than or equal to 1.5 mM), a Ca2+ chelator, almost completely inhibited the PMA-induced AA release without affecting the intrinsic AA release. Preincubation with staurosporine (5-20 nM), an inhibitor of protein kinase C (PKC), partially (approximately 60%) blocked the AA release. However, 30-min preincubation with H-7 (50-200 microM), an inhibitor of PKC, failed to block the AA release. PMA, thus, appeared to stimulate AA release partially by a staurosporine-sensitive mechanism, probably an activation of PKC, in an external Ca(2+)-dependent manner. On the other hand, MOB 3-4 cells responded to PMA with an increased AA release but not with a drastic change of its shape. Both staurosporine and BAPTA exerted similar inhibitory effects. Prolonged exposure (48 h) to PMA (0.1-10 nM) enhanced DNA synthesis of MOB 3-4-F2 cells, but not MOB 3-4 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ipriflavone and estrogen on the differentiation and proliferation of osteogenic cells

The effect of ipriflavone (IP) on the proliferation and differentiation of rat osteoblast-like (ROB) cells and human periodontal ligament fibroblasts (HPLF) was studied in the presence and absence of estrogen. ROB cells were isolated from newborn rat calvaria by sequential collagenase digestion and HPLF from the outgrowth of human periodontal ligament in culture. The alkaline phosphatase (ALP) activity, employed as a marker of bone cell differentiation, was significantly enhanced by IP in both cell types; however, the concentration at which IP had a maximal effect was lower in ROB cells than in HPLF (10(-10) versus 10(-7) M, respectively). Cell proliferation judged by DNA content was either constant (ROB cells) or slightly increased (HPLF) by IP up to 10(-10) M, and decreased significantly above that concentration. In addition, the dose-dependent effect of estrogen on the growth and differentiation of each cell type in the presence and absence of IP was also tested. At the concentrations of IP which showed maximum effects in the induction of ALP, 10(-10) M for ROB cells and 10(-7) M for HPLF, IP inhibited DNA increase in an estrogen-independent manner. Estradiol (10(-11)-10(-9) M) itself increased the growth rate of both cell types significantly in a dose-dependent manner. Regardless of the concentrations of estradiol tested, ALP activities of both ROB cells and HPLF were elevated by the addition of IP. The ratio of ALP in the presence and absence of IP was similar over the range of estradiol concentrations tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium in osteoblast-enriched bone cells

The exchangeability, location, and amount of the total calcium in bone cells were studied in relation to their osteoblastic activity. Cells were isolated from neonatal rat calvariae by sequential collagenase digestion and incubated with 45Ca2+ before or after various treatments. 45Ca2+, 40Ca2+, and DNA were determined on each cell sample. Long-term experiments were performed on cultured cells. The cells closest to the forming bone had the highest alkaline phosphatase activity and the highest Ca2+ content (i.e., 17 mm Ca2+/l cell water, as compared to soft tissue cells, which have 2-3 mm Ca2+/l (Borle 1981). About 50% of this Ca2+ exchanges readily with 45Ca2+ and appears to be located almost entirely in the cell membrane. Thirty-five percent exchanges only slowly with a t1/2 of 27 hours, and is located within the cell, principally in the mitochondria as seen in pyroantimonate fixed cells (Neuman et al. 1985). In spite of its slow exchange-ability, this Ca2+ fraction can be mobilized or augmented rapidly when Ca2+ supply is reduced or increased in vitro or in vivo. 1,25(OH)2D3 given in vivo increased this intracellular Ca2+ when the Ca2+ supply was low and released it when the Ca2+ supply was high. About 15% of the Ca2+ in these cells was nonexchangeable. These results suggest that osteoblasts do process more Ca2+ when closer to the mineralization site. Whether this Ca2+ is en route from blood to bone or from bone to blood will require further study.

[Radiosensitive malignant meningioma presenting Garcin's syndrome: a case report]

A 58-year-old woman with Garcin's syndrome caused by malignant meningioma is reported. She first noticed left facial hypesthesia followed by left visual disturbance with exophthalmos. CT scan showed an enhanced mass extending from the left cavernous sinus to the left orbit. Cranial x-ray revealed bone deformity around the orbit. The tumor was subtotally resected and its histological type was shown to be anaplastic meningioma. After the initial surgery the patient was left with hyposmia, mild ptosis and incomplete 6th cranial nerve palsy on the left side. After one and half years, not only palsy of those cranial nerves but also that of other unilateral cranial nerves became progressively apparent due to tumor regrowth. In total, 11 nerves (2nd-12th) were affected by the tumor, without long tract signs or symptoms of increased intracranial pressure. Radiation therapy carried out after the 2nd surgery was extremely effective and resulted in the recovery of lower cranial nerve function. The tumor was founded to have disappeared completely on the 2-year follow-up CT.

Aluminofluoride- and epidermal growth factor-stimulated DNA synthesis in MOB 3-4-F2 cells

In attempt to study the mechanism of F(-)-induced, osteoblast-mediated bone formation, we tried to show the characteristics of Al-F complex-induced mitogenesis in osteoblastic cells. The MOB 3-4-F2 cell line, an osteoblast-like cell line derived from neonatal mouse calvaria, responded to F- (1-2 mM) combined with Al3+ and epidermal growth factor (EGF, 0.01-100 ng/ml) with increased DNA synthesis. Of the several types of Al-F complexes, AlF4- is thought to act as a mitogenic factor. On the other hand, NaF at high concentrations (greater than 2 mM) markedly decreased cell viability. The AlF(4-)-stimulated DNA synthesis at least with a delay of 48 hr, while EGF stimulated DNA synthesis within a few hours (4-6 hr). Both 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) and staurosporine, inhibitors of protein kinase C (PKC), further enhanced DNA synthesis in AlF(4-)-treated cells, whereas 12-O-tetradecanoyl-13-acetate (TPA), an activator of PKC, decreased the DNA synthesis. In EGF-treated cells, staurosporine and TPA, but not H-7, decreased DNA synthesis. In addition, indomethacin, an inhibitor of cyclooxygenase, partly inhibited the EGF-induced mitogenesis, which, however, was restored by addition of PGE2. AlF4-, as well as EGF, stimulated the release of arachidonic acid and its metabolites. Indomethacin failed to inhibit the AlF(4-)-induced mitogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

A case of malignant lymphoma in the liver treated by percutaneous ethanol injection therapy under peritoneoscopic observation

A 41-year-old woman with non-Hodgkin's lymphoma in the liver was treated with percutaneous ethanol injection therapy. Ethanol injection was performed twice under ultrasonographic guidance for a lesion inside the liver and once under peritoneoscopic observation for lesions on the surface of the liver. CT performed after treatment showed that sizes of the lesions decreased and that the lesions were not enhanced by contrast medium, indicating lack of blood supply and necrosis of the lesion. Ultrasonography performed after treatment did not show any lesions in the liver. There was no sign of recurrence or metastasis.

Anterior transpetrosal-transtentorial approach for sphenopetroclival meningiomas: surgical method and results in 10 patients

This report presents a new surgical method and the results in 10 patients with petroclival meningiomas extending into the parasellar region (sphenopetroclival meningiomas). Minimal but effective extradural resection of the anterior petrous bone via a middle fossa craniotomy offered a direct view of the clival area with preservation of the temporal bridging veins and cochlear organs. The dural incision was extended anteriorly to Meckel's cave, and in cases with invasion of the cavernous sinus, Parkinson's triangle was enlarged by mobilization of the trigeminal nerve. This approach offered an excellent view from the mid-clivus to the cavernous sinus. Extra-as well as intradural tumor masses and dural attachments could be cleared under direct view of the pontine surface. The risk of injury to the lower cranial nerve and of retraction damage to the temporal lobe and brain stem were kept minimal by this approach. Total tumor resection was achieved in 7 patients, with no resultant mortality. Eight patients had a satisfactory postsurgical course, extraocular paresis being their main complaint. The extent of tumor resection depended on the degree of tumor adhesion to the carotid artery, and operative morbidity on the degree of tumor invasion of the brain stem. Of the 3 patients in whom subtotal tumor removal was achieved, only one experienced regrowth of the tumor and underwent a second operation during the follow-up period (6 months-6 years).

[Clinical study of vitamin E status in patients with chronic liver diseases]

Vitamin E status was evaluated in patients with chronic liver diseases (chronic hepatitis, CH; n = 27 and liver cirrhosis, LC; n = 32) by the ratio of plasma alpha-tocopherol to plasma lipids (P-toc/lipid) and red blood cell alpha-tocopherol (RBC-toc). P-toc/lipid and RBC-Toc were significantly reduced in LC patients compared to controls (n = 31). There was a significant correlation between P-Toc/lipid and RBC-Toc values. Low vitamin E status was found in 3 patients with CH (11.1%) and 12 patients with LC (37.5%), but their P-Toc values were not necessarily reduced. Serum beta-lipoprotein concentration (beta-lipo) did not differ significantly between the low vitamin E group and the normal vitamin E group, but the ratio of P-Toc to beta-lipo was significantly reduced in the low vitamin E group. No significant differences were found in the clinical features or liver functions tests including parameters of hepatic synthetic functions and cholestasis between the two groups. Factors other than a cholestasis or an impaired synthesis of carrier protein may also be responsible for the frequent occurrence of low vitamin E status in patients with LC.

[Antitumor effect of direct intra-tumor administration of OK-432 on malignant glioma: basic and clinical observations]

In this study, we tried to examine the efficacy of a cytotoxic factor which is induced by periodic, repeated local administration of OK-432 into the tumor cavity of malignant glioma patients. OK-432 was administered intratumorally via a tube to 4 malignant glioma patients on Days 1, 3, 5, 7 and 12 in doses of 0.5 KE, 1 KE, 2 KE, and 3 KE, respectively. Cerebrospinal fluid (CSF) was collected several times during the 24-hour period beginning immediately after the administration on Day 12. The CSF was added to the culture medium of rat glioma cells (GA-1 and C-6) in order to observe the cytotoxic effect morphologically. The clinical efficacy in the patients was evaluated from the changes in tumor size observed by CT. CSF collected from the tumor cavity of 3 patients was bloody. By adding this bloody CSF, a significant morphological cytotoxic effect was observed on both the GA-1 and C-6 glioma cells in culture. The level of cytotoxicity was higher with the bloody fluid collected at 4 to 24 hours after the final administration than with the bloody fluid collected immediately after the final administration. The cytotoxic effect of this fluid was stronger than that of rabbit TNF (tumor necrosis factor) serum induced with P. acnes and LPS.(ABSTRACT TRUNCATED AT 250 WORDS)

Establishment of murine macrophage-like mutant and hybrid cell lines: comparative analysis of the differentiation induced by 1 alpha,25-dihydroxyvitamin D3 and recombinant murine interferon-gamma

The purpose of this study is to establish the monocyte/macrophage-like cell lines which are sensitive to potent systemic and local factors, 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2 VD3) and interferon-gamma (IFN-gamma). We established two variant mouse macrophage-like cell lines, whose responses to 1 alpha,25(OH)2 VD3 and IFN-gamma differed from one another. The AH-sensitive mutant cell line (G3) was induced by allowing P388D1 tolerant to 8-azaguanine. G3 mutant cells were then fused with the 1 alpha,25(OH)2 VD3-stimulated bone marrow cells isolated from DBA/2 mice. After AH selection the hybrid cell line (XC) was established. The G3 mutant cell line and the XC hybrid cell line had macrophage-like characteristics, such as surface antigens, Fc receptor, C3 receptor, and lysosomal enzymes. The treatment of G3 mutant cells with 1 alpha,25(OH)2 VD3 inhibited cell proliferation with morphological changes, and increased acid phosphatase activity, phagocytic activity, and F4/80 antigen expression on the cell surface. In contrast, IFN-gamma inhibited cell proliferation without effect on acid phosphatase activity and phagocytic activity but increased F4/80 antigen expression. In XC hybrid cells, on the other hand, IFN-gamma, but not 1 alpha,25(OH)2 VD3, inhibited cell proliferation with morphological changes but increased phagocytic activity and F4/80 antigen expression. In addition, IFN-gamma, but not 1 alpha,25(OH)2 VD3, dose-dependently increased multinucleated cell formation of both cells. These findings suggest that the G3 mutant cell line with macrophage-like characteristics is 1 alpha,25(OH)2 VD3- and IFN-gamma-sensitive, and that the XC hybrid cell line is, despite its macrophage-like characteristics, only IFN-gamma-sensitive. Therefore, these newly established cell lines will provide useful systems in studying the differentiation of monocyte/macrophage lineage.

Strategy for the diagnosis of small acoustic neuromas

Twenty small (extra-meatal size less than 15 mm) acoustic neuromas have been diagnosed since high-resolution (HR) magnetic resonance imaging (MRI) became available in our clinic. Among these tumors, 18 had sensorineural hearing loss and 16 enlarged internal auditory meatus in X-ray photo, but only 8 tumors out of 18 tested showed diminished caloric response. Auditory brainstem responses (ABR) has been believed as the most reliable test for the diagnosis of acoustic neuroma despite several reports of false-negatives. In our series, 4 tumors out of 18 tested had normal ABR. The false-negative rate was 22%, which is much higher than expected. In CT, only 11 tumors were recognized. Although the total number is not large, present results clearly suggest the limits of these examinations. At present, HR-MRI is the most reliable diagnostic method for acoustic neuromas with no false-negative reported; ordinary MRI may have false-negatives. For the effective use of MRI, the results of audiometry, X-ray photo, ABR and other examinations must be evaluated properly.

Starvation of a clonal osteoblast-like cell line, MOB 3-4-F2, down-regulates prostaglandin E2 receptors but increases cAMP response to prostaglandin E2

Prostaglandin E2 (PGE2) stimulated cAMP production in the MOB 3-4-F2 cell line, a subclone of the osteoblast-like MOB 3-4 cell line. After being cultured in alpha-minimum essential medium supplemented with 10% heat-inactivated foetal calf serum (HIFCS), cells responded to PGE2 (greater than or equal to 50 ng/ml) with a small, but significant, increase in cAMP production. This response did not vary with duration of culture. In 2% HIFCS-containing medium, despite their lower basal cAMP level, cells responded to PGE2 (greater than or equal to 5 ng/ml) with strikingly increased cAMP production. In addition, prolonged culture in this serum-deficient medium enhanced this response. On the other hand, culture of cells in 2% HIFCS-containing medium decreased the apparent number of PGE2 receptors, which was also enhanced by prolonged culture, without effect on their apparent affinity. Their number in 10% HIFCS-containing medium, more than that in 2% HIFCS-containing medium, was almost constant, independent of the culture period. Starvation of MOB 3-4-F2 cells in serum-deficient medium, therefore, appeared to down-regulate PGE2 receptors but increase the cAMP response to PGE2. Moreover, prolonged starvation of cells appeared to facilitate these phenomena. Our findings suggest that cAMP response to PGE2 does not always reflect the number of available PGE2 receptors in the cells.

Effects of prostaglandin E2 and F2 alpha on cytoplasmic pH in a clonal osteoblast-like cell line, MOB 3-4

Prostaglandin E2 (PGE2, 5 ng/ml to 5 micrograms/ml) induced a dose-dependent increase in cAMP accumulation, inositol phosphates (IPs) accumulation, and cytoplasmic free Ca2+ ([Ca2+]i) in a clonal osteoblast-like cell line, MOB 3-4. In contrast, prostaglandin F2 alpha (PGF2 alpha, 5 ng/ml to 5 micrograms/ml) stimulated increases in IPs accumulation and [Ca2+]i without stimulating an increase in cAMP accumulation. Both PGE2 (greater than 0.5 micrograms/ml) and PGF2 alpha (greater than or equal to 5 micrograms/ml) increased cytoplasmic pH (pHi) from approximately 7.15 to 7.35 in BCECF-loaded cells. A tumor promotor, phorbol 12-myristate 13-acetate (PMA, 0.1-100 nM) also increased pHi without effect on phosphoinositide hydrolysis. Both PGE2-(5 micrograms/ml) and PMA- (100 nM) induced cytoplasmic alkalinization was inhibited by removal of extracellular Na+, or by pretreatment of the cells with amiloride (0.5 mM), an inhibitor of Na+/H+ exchange, or H-7 (100 microM), a nonspecific inhibitor of protein kinase C. Thus, MOB 3-4 cells appeared to possess PGE2 receptors and PGF2 alpha receptors: the former are coupled to adenylate cyclase and phospholipase C, and the latter are predominantly coupled to phospholipase C. Also the cells appeared to possess an amiloride-sensitive Na+/H+ exchange activity, which increases pHi in response to PGE2 and PGF2 alpha, as well as to PMA. Long-term (48 hr) exposure of the cells to PGE2 at a high concentration (5 micrograms/ml), but not to PGF2 alpha and PMA, decreased DNA synthesis in the serum-deficient medium. Thus, cytoplasmic alkalinization appeared insufficient for cell replication. At least in MOB 3-4 cells, the inhibitory effect of PGE2 on DNA synthesis may be due to the cAMP messenger system.

A clonal prostaglandin-responsive cell line (RDP 4-1) derived from rat dental pulp

The RDP 4-1 cell line was established from isolated rat dental pulp and cloned with limiting dilution in 96-multiwell plates. Despite their fibroblast-like appearance, RDP 4-1 cells required more than 5% (v/v) heat-inactivated fetal calf serum to maintain the cell growth and function. Type I collagen, but not type II and type III collagen, was immunocytochemically detected in the cells in subconfluent cultures. Prostaglandin E2 (PGE2, 5 ng/ml-5 micrograms/ml) dose-dependently increased cAMP accumulation, while prostaglandin F2 alpha (PGF2 alpha, 5 micrograms/ml) slightly increased it, in the presence of 0.1 mM isobutylmethyl xanthine. PGE2 (5 ng/ml-5 micrograms/ml) also stimulated phosphoinositide hydrolysis to produce inositol phosphates (IPs) in a time- and dose-dependent manner in the presence of 10 mM LiCl. PGF2 alpha was a more potent stimulator of phosphoinositide hydrolysis. Both prostaglandins increased cytoplasmic free calcium, independent of the level of extracellular calcium. Prolonged exposure (48 h) of the cells to PGE2 at higher concentrations (greater than or equal to 0.5 micrograms/ml) increased DNA synthesis. In these RDP 4-1 cells, thus, PGE2 receptors appeared to be associated with both cAMP and IPs-Ca2+ signaling systems, and that PGF2 alpha receptors are poor stimulators of the former but more potent ones of the latter. Our results suggest that both prostaglandins have some roles in regulating dental pulp metabolism.

Impaired regulation of natural killer cells in immunoglobulin synthesis by peripheral blood mononuclear cells from patients with ulcerative colitis

Immunoglobulin (Ig) synthesis, natural killer (NK) cell activity, and lymphokine production by peripheral blood mononuclear cells (PBMC) were studied in 34 patients with ulcerative colitis (UC). Levels of Ig produced by PBMC were significantly higher in patients with active UC as compared to controls. However, there were no significant differences in Ig-synthesis between patients with inactive UC and controls. NK cell activity was significantly decreased in patients with active UC as compared to controls, and a significant negative correlation was observed between the level of IgA and NK cell activity in patients with UC. Reconstitution experiments demonstrated that CD56+ cells from controls suppressed the levels of IgA, when added to the culture containing a constant number of B cells and CD4+ cells. In contrast, CD56+ cells from patients with active UC completely lacked the capacity to suppress IgA production. In addition, the activities of interleukin-2 and interferon-gamma were significantly decreased in patients with active UC. The present study suggests that immunoregulatory abnormality of NK cells exists in patients with UC and impaired NK cell activity may be related to increased Ig-synthesis observed in these patients.

The effects of pressure on cochlear microphonics in experimentally induced hydropic ears in the guinea pig

The effect of perilymphatic pressure on the cochlear microphonics (CM) threshold was examined in guinea pigs with experimentally induced hydrops. When a pressure of 300 mm H2O was applied to the scala tympani of the basal turn, the 500 Hz CM threshold shifts in ears during the 1st week following obliteration of the endolymphatic sac and duct were significantly smaller when compared with shifts in normal ears. Larger threshold shifts were then regained at 4-12 weeks after surgery. When acetazolamide was administered to hydropic animals, the effect of the increase of perilymphatic pressure on the CM threshold was also investigated. During the 1st postoperative week (4-7 days after surgery), CM threshold shifts were larger when compared to changes in hydropic animals without medication. The CM depression as the result of pressure is probably due to a mechanical effect on the intracochlear partition.

Initial responses of a clonal osteoblast-like cell line, MOB 3-4, to phosphatidic acid in vitro

A number of studies have shown membrane phospholipid metabolism to have an important role in biological mineralization. We considered the effects of exogenously applied phosphatidic acid (PA), a minor component of membrane phospholipids, on an osteoblast-like cell line, MOB 3-4. Exogenous PA (10-40 micrograms/ml) raised the level of cytoplasmic free Ca2+ [( Ca2+]i), independent of the level of extracellular Ca2+, in a dose-dependent fashion, and this Ca2+ response to PA gradually fell on serial application of PA. In a dose-dependent manner, exogenous PA also increased inositol 1,4,5-trisphosphate (IP3) accumulation and cytoplasmic pH, but decreased basal cAMP level. This cytoplasmic alkalinization was inhibited by pretreatment with nonspecific protein kinase C (PKC) inhibitors, such as sphingosine or H-7. A long-term incubation with PA increased alkaline phosphatase (ALP) activity and cell proliferation. Exogenous PA thus appeared to increase IP3 accumulation by activating phospholipase C, raise [Ca2+] by releasing Ca2+ from intracellular stores, induce cytoplasmic alkalinization via a PKC-dependent mechanism, and simultaneously decrease basal cAMP level. We suggest that these initial responses may be responsible for the increase in ALP activity and the proliferation of PA-treated MOB 3-4 cells.