Phantom study for CT artifacts of dental titanium implants and zirconia upper structures: the effects of occlusal plane angle setting and SEMAR algorithm

OBJECTIVES

The single-energy metal artifact reduction (SEMAR) algorithm effectively reduces metal artifacts in computed tomography (CT). The study aimed to evaluate the effect of the occlusal plane angle on metal artifacts caused by dental implants and zirconia upper structures, and the effectiveness of SEMAR for CT prognostic evaluation.

METHODS

Part of a bovine rib was used as the mandibular implant phantom. First, the phantom immersed in a water tank was scanned using CT to obtain the control image under certain conditions. Subsequently, three titanium implant bodies were implanted in a straight line into the phantom, and a zirconia superstructure was attached. CT scans were performed. The CT-reconstructed images were obtained with and without SEMAR processing. Twelve regions of interest (ROIs) were set at the same site on each sagittal image, and the CT values were measured at all the ROIs. The CT values of the ROIs in the control images and those of the ROIs with and without SEMAR were compared.

RESULTS

The variations in the occlusal plane angle during CT imaging negligibly affected the number of regions in which metal artifacts appeared. SEMAR improved the CT value of the trabecular bone, which was affected by metal artifacts.

CONCLUSION

This study showed that the occlusal plane angle occasionally did not affect the area of metal artifacts caused by dental implants or zirconia upper structures. Other results indicate that SEMAR is effective for accurately evaluating the alveolar bone around the implant body by reducing metal artifacts.

Eribulin mesylate induces bone mass loss by promoting osteoclastic bone resorption in mice

Over the past few decades, the clinical outcomes of patients with cancer have significantly improved mostly owing to the development of effective chemotherapeutic treatments. However, chronic health conditions such as bone mass loss and risk of fragility fractures caused by chemotherapy have also emerged as crucial issues in patients treated for cancer. In this study, we aimed to understand the effect of eribulin mesylate (ERI), a microtubule-targeting agent currently used to treat metastatic breast cancer and certain subtypes of advanced sarcomas, on bone metabolism in mice. The administration of ERI reduced bone mass in mice, mainly by promoting osteoclast activity. Gene expression analysis of skeletal tissues revealed no change in the expression levels of the transcripts for RANK ligand, one of the master regulators of osteoclastogenesis; however, the transcript levels of osteoprotegerin, which neutralizes RANK ligand, were significantly reduced in ERI-treated mice compared with those in vehicle-treated controls, indicating a relative increase in RANK ligand availability after ERI treatment. In line with the increased bone resorption in ERI-treated mice, we found that zoledronate administration effectively suppressed bone loss in these mice. These results reveal a previously unrecognized effect of ERI on bone metabolism and suggest the application of bisphosphonates for patients with cancer undergoing treatment with ERI.

Effects of paprika carotenoid supplementation on bone turnover in postmenopausal women: a randomized, double-blind, placebo-controlled, parallel-group comparison study

Background

Paprika (Capsicum annuum L.) is a good source of carotenoids, including capsanthin, β-carotene, β-cryptoxanthin, and zeaxanthin. Several epidemiological studies have shown a beneficial association of intake of these carotenoids or their blood concentration with bone mineral density (BMD) and fracture risk. However, little information is available regarding the effect of intake of these carotenoids on bone metabolism in postmenopausal women.

Objective

The objective of the present study was to investigate the effects of paprika carotenoid extract (PCE) on bone turnover in healthy, postmenopausal women.

Design

We conducted a randomized, double-blind, placebo-controlled, parallel-group comparison study. One hundred participants were randomly assigned to PCE or placebo groups. Each group was given a 20 mg PCE (equivalent to 1.4 mg of carotenoids) a day or a placebo for 24 weeks. We measured bone resorption markers (tartrate-resistant acid phosphatase 5b [TRACP-5b] and serum type I collagen cross-linked N-telopeptide [sNTX]) at 12 and 24 weeks and bone formation markers (bone alkaline phosphatase and osteocalcin) at 24 weeks.

Results

The percentage decrease of TRACP-5b at 24 weeks was significantly higher for PCE than the placebo. There were no significant differences in sNTX or bone formation markers, although PCE decreased each marker compared with the placebo.

Conclusion

Our findings suggest that PCE supplementation suppresses bone resorption and contributes to maintaining bone quality in postmenopausal women.

Nanosized Hydroxyapatite Coating on PEEK Implants Enhances Early Bone Formation: A Histological and Three-Dimensional Investigation in Rabbit Bone

Polyether ether ketone (PEEK) has been frequently used in spinal surgery with good clinical results. The material has a low elastic modulus and is radiolucent. However, in oral implantology PEEK has displayed inferior ability to osseointegrate compared to titanium materials. One idea to reinforce PEEK would be to coat it with hydroxyapatite (HA), a ceramic material of good biocompatibility. In the present study we analyzed HA-coated PEEK tibial implants via histology and radiography when following up at 3 and 12 weeks. Of the 48 implants, 24 were HA-coated PEEK screws (test) and another 24 implants served as uncoated PEEK controls. HA-coated PEEK implants were always osseointegrated. The total bone area (BA) was higher for test compared to control implants at 3 (p < 0.05) and 12 weeks (p < 0.05). Mean bone implant contact (BIC) percentage was significantly higher (p = 0.024) for the test compared to control implants at 3 weeks and higher without statistical significance at 12 weeks. The effect of HA-coating was concluded to be significant with respect to early bone formation, and HA-coated PEEK implants may represent a good material to serve as bone anchored clinical devices.

Differential age-related bone architecture changes between female and male STR/Ort mice

The incidence of spontaneous osteoarthritis (OA) in female STR/Ort mice is much lower than that observed in male STR/Ort mice; however, the reason for the differential incidence of OA between sexes has not been elucidated. Here, we investigated and compared age- and sex-related bone mineral density and architectural changes in male and female STR/Ort mice. Bone architecture and bone mineral density (BMD) of femurs were examined in 5-, 10-, 15-, 20-, and 35-week-old male and female STR/Ort mice by microscopic computed tomography (µCT). Angular degrees of internal tibial torsion (ADITT) were also measured in mice at 5, 15, and 35 weeks of age. Earlier decreases of cancellous volume and BMD were found in male STR/Ort mice. Using µCT, an age-related decline of bone marrow space in femoral diaphysis was observed in both males and females but was more dramatic in females. In addition, an earlier increase of ADITT was observed in male STR/Ort mice, suggesting that internal rotation of the tibia may contribute to OA. Age- and sex-related bone architectural changes clearly differ between male and female STR/Ort mice. These differences in bone structure, particularly ADITT, may explain the differential incidence of OA in STR/Ort mice.

A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats

Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical.

Detecting young Japanese adults with undetected low skeletal bone density using panoramic radiographs

OBJECTIVE

The cortical width below the mental foramen of the mandible determined from panoramic radiographs is a useful screening tool for identifying elderly individuals with a low skeletal bone mineral density (BMD). However, whether the mandible cortical width (MCW) is useful for identifying a low skeletal BMD in men and women of 40 years or younger is not known.

METHODS

The BMD of the calcaneus was measured by ultrasonography bone densitometry in 158 men and 76 women aged 18-36 years. A logistic regression analysis adjusted for age was used to calculate the odds ratios and 95% confidence interval (CI) of having a low calcaneal BMD, according to the quartiles of the MCW. The areas under the receiver operator characteristic curve (AUC) for identifying participants with a low calcaneal BMD using the MCW were assessed to evaluate the diagnostic efficacy of the MCW.

RESULTS

In men, the adjusted odds ratios of a low calcaneal BMD associated with the second, third and lowest quartiles of MCW were 5.66 (95% CI, 0.61-52.23), 5.43 (95% CI, 0.59-50.18) and 33.22 (95% CI, 3.97-276.94), respectively, compared with the highest quartile, while no significant trend in the adjusted odds ratios was observed in women. The AUC for identifying participants with a low calcaneal BMD based on the MCW was 0.796 (95% CI, 0.702-0.890) in men and 0.593 (95% CI, 0.398-0.788) in women.

CONCLUSION

MCW determined from panoramic radiographs can be used to identify undetected low calcaneus BMD in young adult men, but not in young adult women.

Prolonged endochondral bone healing in senescence is shortened by low-intensity pulsed ultrasound in a manner dependent on COX-2

To test whether mechanical loading produces faster healing in aged mice, fractured femurs of aged 1-year-old mice were subjected to low-intensity pulsed ultrasound (LIPUS), a treatment that is routinely used to help heal fractures in humans. Cyclooxygenase-2 knockout mice (COX-2(-/-)), which lack an immediate early mediator of mechanical stimulation, were also studied by histochemistry, microcomputed tomography and quantitative polymerase chain reaction to determine the role of COX-2. The healing in the aged COX-2(-/-) mice is slow during the endochondral bone remodeling (>30 d), a period generally prolonged in senescence. For aged wild-type mice, LIPUS halved the endochondral phase to about 10 d, whereas that was not the case for aged COX-2(-/-) mice, which showed no apparent shortening of the prolonged endochondral-phase healing time. Injecting prostaglandin E(2) receptor agonists, however, rescued the COX-2(-/-) callus from insensitivity to LIPUS. In conclusion, COX-2 is a limiting factor in the delayed endochondral bone healing and is induced by LIPUS, which normalizes healing rate to the wild-type level.

Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

OBJECTIVES

The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction.

METHODS

Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose.

RESULTS

The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC.

CONCLUSIONS

The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction.

Prior treatment with vitamin K(2) significantly improves the efficacy of risedronate

Prior 8-week treatment with menatetrenone, MK-4, followed by 8-week risedronate prevented the shortcomings of individual drugs and significantly increased the strength of ovariectomized ICR mouse femur compared to the ovariectomized (OVX) controls. Neither MK-4 following risedronate nor the concomitant administration may be recommended because they brought the least beneficial effect.

INTRODUCTION

The objective of this study was to determine the best combinatory administration of risedronate at 0.25 mg/kg/day (R) with vitamin K(2) at approximately 100 microg MK-4/kg/day (K) to improve strength of osteoporotic mouse bone.

METHODS

Thirteen-week-old ICR mice, ovariectomized at 9-week, were treated for 8 weeks with R, K, or R plus K (R/K), and then, either the treatment was withdrawn (WO) or switched to K or R in the case of R and K. After another 8 weeks, the mice were killed, and mechanical tests and analyses of femur properties by peripheral quantitative computed tomography, microfocus X-ray tube computed tomography, and confocal laser Raman microspectroscopy were carried out.

RESULTS

The K to R femur turned out superior in parameters tested such as material properties, bone mineral density, BMC, trabecular structure, and geometry of the cortex. The increased cross-sectional moment of inertia, which occurred after K withdrawal, was prevented by risedronate in K to R. In addition to K to R, some properties of R to WO diaphysis and K to WO epiphysis were significantly better than OVX controls.

CONCLUSION

Prior treatment with MK-4 followed by risedronate significantly increased femur strength in comparison to the OVX controls.

Osteoarthritic changes of the patellofemoral joint in STR/OrtCrlj mice are the earliest detectable changes and may be caused by internal tibial torsion

STR/ort mice develop a naturally occurring osteoarthritis (OA) of the knee joints. However, the evaluation of early OA changes has been difficult due to variability caused by gender, individual differences, and differences between the right and left lower limbs. The objective of this study was to analyze the variability of the early OA changes with age in STR/ort mice and to identify the cause of onset. A total of 115 STR/OrtCrlj mice aged 10-45 weeks were examined. In addition to conventional radiological and histological evaluation of the knee joints, histological sections were used to examine the patellofemoral, femorotibial, and growth plate cartilage under similar conditions. A morphological evaluation of tibiae, including micro-3-dimensional computed tomography, was performed. Radiological evaluation showed OA changes in the joints of mice over 35 weeks old and histological evaluation showed early OA changes in the femorotibial joints of mice over 26 weeks old. However, these changes were not common in all individuals. In contrast, most common and reproducible OA changes were observed in the bilateral patellofemoral joints of all individuals, and even in subjects ranging from 10 to 20 weeks of age. Morphological evaluations also demonstrated an abnormal tibial internal torsion that increased with age and was associated with medial patellar dislocation. In conclusion, the earliest histological OA change was observed in the patellofemoral joint prior to similar observations in the femorotibial joint. Internal tibial torsion may be a cause of OA in the patellofemoral joints, which leads to the development of medial femorotibial OA.

Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy

TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.

Long-Term Prognosis of Acute Aortic Dissection With Medical Treatment. A Survey of 263 Unoperated Patients

Between 1973 and 1998, 263 patients with acute aortic dissection were medically treated only. They were divided into 4 groups: Stanford type A and B with open false lumen (open) or with early thrombosed false lumen (thrombosed). An event was defined as death by dissection or re-dissection. Gender, age, maximum diameter of dissected aorta and presence of shock at onset were examined as risk factors. In the open false lumen group, the presence of shock was associated with the event. During the chronic period, the diameter of the aorta was associated with prognosis in open type B dissection. The rate of event was higher in the open type A and B groups than in the thrombosed type A and B groups; however, there was no difference in the event-free rate between types A and B in patients surviving the acute period. The prognosis of medically treated dissecting aorta was not poor in patients with type B or with early thrombosed false lumen. The presence of shock at onset with open false lumen and the diameter of the aorta (> or =40 mm) in type B were significantly correlated with a poor prognosis.

Cytostatic inhibition of endothelial cell growth by the angiogenesis inhibitor TNP-470 (AGM-1470)

Recently, we reported the anti-angiogenic action along with anti-tumour activity of TNP-470 (AGM-1470). In this study, the effect of TNP-470 on the growth of human umbilical vein endothelial (HUVE) cells was examined. TNP-470 inhibited the growth of HUVE cells in a biphasic manner. The inhibition was cytostatic in the first phase (complete inhibition at 300 pg ml-1 to 3 micrograms ml-1 with an IC50 of 15 pg ml-1) and cytotoxic in the second phase (> or = 30 micrograms ml-1). The cytostatic inhibition of HUVE cell growth by TNP-470 was durable after washing out TNP-470 in culture. Incorporation of thymidine but not uridine and leucine by HUVE cells was inhibited in the first phase, while that of all three compounds was inhibited in the second phase. Human and rat endothelial cells among various types of cells were the most sensitive to the cytostatic inhibition, while differences in the cytotoxic inhibition were minimal. These results suggest that TNP-470 exerts its specific anti-angiogenic action by inhibiting cytostatically growth of endothelial cells in a relatively specific manner.

Scintigraphic detection of xenografted tumors producing human basic fibroblast growth factor

A murine monoclonal antibody 3H3 recognizes the basic fibroblast growth factor (FGF) and inhibits the growth of human glioblastoma cells both in vitro and in vivo. We studied the potential of a scintigraphic technique using the 3H3 antibody to detect tumors that produce basic FGF. 125I- and 111In-labeled 3H3 bound to U87MG human glioblastoma cells in vitro. U87MG cells were inoculated subcutaneously into nude mice. After development of the tumor, radiolabeled 3H3 was injected into the subcutaneous space surrounding the tumor. A high level of radioactivity from 3H3 was retained at the tumor, whereas an irrelevant antibody cleared rapidly from the injected site. Radiolabeled 3H3 was not retained in tumors that did not produce basic FGF. Scintigraphic detection of tumors expressing basic FGF would be valuable for the therapeutic application of the antibody.

Chemistry and anti-tumor activity of sperabillin polymers

Sperabillin A, 3-[[(3R,5R)-3-amino-6-[(2E,4Z)-2,4-hexadienoylamino]- 5-hydroxyhexanoyl]amino]propanamidine dihydrochloride, was polymerized on standing for several days under a highly humid atmosphere or in the presence of radical initiators. The average molecular weight of the polymers obtained could be regulated by changing the reaction conditions in the latter case. Spectral analyses of the polymers revealed that the 2,4-hexadienoyl moiety of sperabillins was polymerized in a free radical-initiated reaction. The polymers selectively inhibited the proliferation of human umbilical vein endothelial (HUVE) cells. Polymers having higher molecular weight showed stronger inhibition of HUVE cell proliferation. In addition, the polymers showed anti-tumor activity against B16 melanoma in vivo.

[Four cases of Hodgkin's disease treated with MOPP/ABV hybrid regimen using nitrogen mustard-N-oxide hydrochloride]

Four patients with fresh Hodgkin's disease were treated with MOPP/ABV hybrid regimen using nitrogen mustard-N-oxide hydrochloride (NH2-O). All patients responded well to this therapy and achieved complete remission. Toxicity was minimum except for an older patient. He was 70 years old and developed arrhythmia after MOPP therapy but recovered without any treatment. The continuation of therapy was possible by dose reduction in this case. We conclude MOPP/ABV regimen using NH2-O is valuable for the treatment of Hodgkin's disease.

Chemical modification of fumagillin. I. 6-O-acyl, 6-O-sulfonyl, 6-O-alkyl, and 6-O-(N-substituted-carbamoyl)fumagillols

The hydroxy group of fumagillol (3), a degradation product of fumagillin (1), was acylated, sulfonylated, alkylated or carbamoylated, and the anti-angiogenic activity of the resulting products was examined. These compounds inhibited the angiogenesis induced by basic fibroblast growth factor in the rat corneal micropocket assay and the growth of vascular endothelial cells in vitro. Among them, compound 2 (AGM-1470) was found to show the most potent inhibitory effect on the growth of vascular endothelial cells and was selected from this series as a candidate for further development.

Suppression of solid tumor growth by immunoneutralizing monoclonal antibody against human basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) is a potent angiogenic mitogen. To elucidate the effect of bFGF inhibitors in vivo, anti-bFGF immunoneutralizing monoclonal antibody was prepared. One monoclonal antibody against human bFGF, obtained by cell fusion and designated 3H3, completely inhibited bFGF-induced proliferation of human umbilical vein endothelial cells at a concentration of 100 ng/ml. 3H3 did not bind to acidic fibroblast growth factor or HST1 protein, indicating high specificity for bFGF. Furthermore, the immunoneutralizing activity of 3H3 was examined in vivo. K1000 cells (a BALB/c 3T3 transformant in which the leader sequence-fused bFGF gene was transfected) were transplanted s.c. into BALB/c nude mice. Growth of the tumor cells was inhibited by i.v. treatment with 3H3 at a concentration of 200 micrograms/mouse. Histological observation showed that the antitumor effect of 3H3 was due to the inhibition of bFGF-induced angiogenesis. This experiment provides direct causal evidence for the hypothesis that tumor growth is angiogenesis dependent. This finding could also have implications for the development of novel therapeutic approaches to angiogenic solid tumors.

Inhibition of cell growth and tumorigenesis of human glioblastoma cells by a neutralizing antibody against human basic fibroblast growth factor

We report here that a neutralizing mouse monoclonal antibody against basic FGF inhibited both anchorage-dependent and anchorage-independent growth of U-87MG and T98G human glioblastoma cells and HeLa cells, all of which express both the basic FGF and the FGF receptor genes. In addition, the subcutaneous administration of this antibody significantly suppressed the tumor development of these tumor cells in nude mice. Therefore, basic FGF plays an important role in neoplastic growth of these cells. The neutralization of basic FGF will be effective in controlling the growth of tumors, such as glioblastoma and other cancer cells which bear basic FGF and FGF receptors.

A sensitive enzyme immunoassay for human basic fibroblast growth factor

A sensitive sandwich enzyme immunoassay for human basic fibroblast growth factor (HbFGF) was developed employing three monoclonal antibodies (MAb3H3, MAb98 and MAb52). The Fab' fragment of MAb3H3 which inhibits HbFGF biological activity was conjugated to horseradish peroxidase. A mixture of MAb52 and MAb98 was used in the solid phase. Neither human acidic fibroblast growth factor, hst-1/KS3 product nor acid denatured HbFGF was cross-reactive in this assay system. The detection limit of this assay system was 1 pg/well. Using this assay, some tumor cell lines were revealed to produce a higher level of bFGF than a normal one. Serum samples from normal volunteers were also assayed, and immuno-reactive HbFGF could be detected in 16 out of 57 samples at range 30 approximately 206 pg/ml.

Synthesis and antitumor activity of new amphiphilic alkylglycerolipids substituted with a polar head group, 2-(2-trimethylammonioethoxy)ethyl or a congeneric oligo(ethyleneoxy)ethyl group

A new series of amphiphilic 1-octadecyl glycerolipids (eleven compounds, 1a-k) were designed and synthesized, in which the 3-phosphocholine portion of platelet-activating factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) was replaced by the 2-(2-trimethylammonioethoxy)ethyl group and congeneric groups having oligo(ethyleneoxy)ethyl bridges of various lengths at position 3, together with modification at position 2 (lower alkyl, acetonyl, acetoacetyl, carboxymethyl and pyrimidin-2-yl groups). These ether lipids, characterized by a nonphosphorus lysoglycerolipid structure, showed potent antitumor activity in vitro (human promyelocytic leukemia cells, HL-60, and human epidermoid carcinoma cells, KB) and in vivo (mouse sarcoma S180 and mouse mammary carcinoma MM46). Maximal in vitro potency was obtained with 1-O-octadecyl-2-O-(2-pyrimidinyl)-3-O-[2-(2-trimethylammonioethoxy )ethyl] glycerol (1g; IC50 values for both HL-60 and KB were 0.32 microgram/ml, indicating a higher activity than alkyl-lysophospholipid, ET18-OMe). Several appropriately 2-substituted 1-octadecylglycerolipids with the 3-[2-(2-trimethylammonioethoxy)ethyl] group (e.g., methyl, 1b; butyl, 1f; 2,2,2-trifluoroethyl, 1j; and acetonyl, 1k) showed a potent life-span-prolonging effect on mice with ascites sarcoma S180 and on those with mammary carcinoma MM46, when administered intraperitoneally at 16.5 and 12.5 mg/kg/d, respectively. Compounds 1b and 1k showed definite tumor growth inhibition against solid sarcoma S180 in mice, whether given p.o. or i.v. at 16.5 mg/kg/d. Studies on the structure-activity relationships indicate that the metabolic stability to phospholipase C or related enzymes is at least partly responsible for the potent antitumor activity of this series of ether lipids.

[Effects of recombinant human interferon-alpha A/D on the growth of experimental tumors in mice]

The effects of recombinant human interferon-alpha A/D (rIFN-alpha A/D, a subtype of recombinant human leukocyte interferon with biological activities against murine tumor cells) on the growth of murine tumors were studied. rIFN-alpha A/D significantly inhibited the growth of mouse M5076 reticulum cell sarcoma, MOPC-104E myeloma, colon carcinoma 26 and Meth A fibrosarcoma by dose-dependent fashion. rIFN-alpha A/D also inhibited the metastases and growth of Lewis lung carcinoma and showed a synergistic effect with combination of cyclophosphamide. The antitumor activity of rIFN-alpha A/D was observed by intra-muscular, intravenous, subcutaneous, intraperitoneal injections or by the injection at the site of the tumors.

Antitumor and cytocidal activities of a newly isolated benzenoid ansamycin, macbecin I

Macbecin I showed marked antitumor activity against intraperitoneally (ip) inoculated leukemia P388, melanoma B16, and Ehrlich carcinoma in mice on ip administration. The maximum effect measured in terms of ILS% (increase of life span) was 97 at a daily dose level of 10 mg/kg for leukemia P388, 103 at 5 mg/kg for melanoma B16, and 206 at 10 mg/kg for Ehrlich carcinoma. The effect of macbecin I on leukemia L1210 was slight (39 ILS%) and no activity was observed against leukemia L5178Y or P388/P-3 (a line of P388 resistant to ansamitocin P-3), or MOPC-104E myloma. Three to six hours after administration of 0.5 mg/kg or more of macbecin I to mice bearing ascites leukemia P388 cells, typical karyorrhexis followed by cytolysis in P388 cells was observed. Cytocidal changes induced by macbecin I were also observed in cells which were temporarily prevented from entering mitosis by treatment with known antitumor agents such as 5-fluorouracil, cyclophosphamide, and neocarzinostatin, whereas such cytolysis was not observed in cells which were arrested in metaphase by treatment with ansamitocin P-3. Cytotoxicity of macbecin I to cultured KB cells was observed at doses of 10(-1) micrograms/ml and more. Reverse transcriptase and terminal deoxynucleotidyl transferase activities were not inhibited by macbecin I.

Spontaneous production of a C-type RNA virus in a cell line derived from rat glioma

The spontaneous production of a rat C-type RNA virus (ACV) in a cultured cell line (AC cells) established from a chemically induced rat glioma was studied. The characteristics of ACV were: morphology typical of C-type RNA virus; buoyant density of 1.15 g/ml in a sucrose density gradient; RNA directed DNA polymerase activity; viral core with a density of 1.28 to 1.30 g/ml; 70S RNA with dimer structure; and structural protein composed of mainly four polypeptides. Kinetical analysis of DNA-DNA hybridization revealed that DNA sequences homologous to DNA transcripts of RNA of ACV were present in rat cells. RNA directed DNA polymerase of ACV partially cross-reacted with antiserum to the polymerase of Rauscher murine leukemia virus. These data suggest that ACV is an endogenous C-type RNA virus of rat origin.

Mechanism of action of 2,2'-(methylenediimino)bis-1,3,4-thiadiazole (NSC 143019), an antitumor agent

The mechanism of action of 2,2'-(methylenediimino)bis-1,3,4-thiadiazole (NSC 143019) was clarified by studies on its effects on monolayer cultures of growing cells of the mouse cell line BALB/3T3. At concentrations below 50 muM, NSC 143019 specifically inhibited DNA and RNA syntheses without appreciably affecting protein synthesis. The syntheses of DNA and RNA were inhibited equally and concomitantly by the compound. The inhibition was reversed by removal of the compound and was prevented competitively by an equimolar amount of nicotinamide. It was also reversed completely by guanosine (0.1 mM) or deoxyguanosine (0.1 mM) and was reversed partially by xanthosine (1 mM). Other nucleosides did not influence the inhibition. The inhibition of DNA synthesis by NSC 143019 was not due to inhibition of RNA synthesis, and vice-versa. NSC 143019 inhibited the conversion of [8-14C]hypoxanthine to acid-soluble and -insoluble guanine nucleotides but not to adenine nucleotides. It was strongly suggested from these results that at concentrations of NSC 143019 below 50 muM the primary action of this compound might be due to the inhibition of GMP biosynthesis at the step of conversion of IMP to xanthosine 5'-phosphate.