Double rule-out technique for evaluation of acute chest pain using 128-row multidetector CT.

AIM: To evaluate the feasibility and image quality of the double rule-out (DRO) technique using 128-row multidetector computed tomography (CT) for simultaneous evaluation of the aorta and coronary arteries in patients with acute non-specific chest pain. MATERIALS AND METHODS: Sixty-eight patients underwent electrocardiography (ECG)-gated coronary CT followed by non-ECG-gated abdominal CT. The contrast-to-noise ratio and signal-to-noise ratio between the vessels and adjacent perivascular fat tissue were calculated for both the aorta and coronary arteries. Dose-length products were recorded. Two blinded readers graded the image quality of the aorta and coronary arteries on a two-point and a four-point scale, respectively. In addition, the severity of coronary stenosis was independently analysed for each coronary vessel. RESULTS: The average attenuation was more than 350 HU for the aorta and >330 HU for the coronary arteries. The average (±standard deviation) volume of contrast media was 69.5 ± 12.5 ml. Interobserver agreement on the image quality of aortic and coronary data sets was perfect and substantial, respectively. There was almost perfect interobserver agreement for the all observations of the severity of coronary stenosis. CONCLUSION: The DRO technique with a standard volume (approximately 70 ml) of contrast media is useful for acute chest pain evaluation in patients suspected of having acute aortic syndrome or acute coronary syndrome. It is also accurate and safe while maintaining the average CT attenuation of the aorta and coronary arteries >330 HU.

Cytohistology of morule in cribriform-morular variant of papillary thyroid carcinoma.

INTRODUCTION: Cribriform-morular variant (CMV) is a rare variant of papillary thyroid carcinoma. It frequently occurs in association with familial adenomatous polyposis (FAP), although some cases are sporadic. Herein, we report a case of CMV and analyse morule cytohistology. CASE REPORT: The patient was a 47-year-old woman with no familial history of FAP. A 3.0-cm unifocal mass was identified in the left thyroidal lobe. Fine-needle aspiration cytology revealed papillary clusters of atypical cells with nuclear grooves, which was suspected to be conventional papillary thyroid carcinoma. Histologically, the tumour comprised a papillary and cribriform growth of atypical cells with cytoplasmic accumulation and nuclear translocation of b-catenin. In addition, frequent morule formation was identified. DISCUSSION: In this case, we performed morule analysis through correlative light and electron microscopy (CLEM), and revealed its ultrastructure. Although CMV is a rare form of thyroid carcinoma, it should be considered along with its distinct clinicopathological characteristics.

Effect of PS-K, a protein polysaccharide, on pulmonary metastases of a C3H mouse squamous cell carcinoma.

We studied the effects of PS-K, a protein polysaccaride isolated from a basidiomycete, on the formation of blood-borne metastases. Experimental tumors were fifth-generation isotransplants of a spontaneous C3Hf mouse squamous cell carcinoma that was weakly antigenic. A single-cell suspension from fourth generation tumors was transplanted, and the tumor-bearing legs of the mice were amputated when transplants reached a certain diameter. Daily administrations of PS-K followed immediately, and both lungs were excised on the 21st postamputation day. The number of lung colonies formed on the surfaces of both lungs was counted and total volumes of metastatic colonies were estimated. PS-K, if administered alone, did not inhibit the lung colony formation. Marked reduction in this formation was observed when five daily doses of PS-K were administered simultaneously with cyclophosphamide. These observations indicate that PS-K may be a potent agent in the therapy of cancer if used as an adjuvant to a chemotherapeutic agent.

Kinetics of thermotolerance in normal and tumor tissues: a review.

Thermotolerance is a phenomenon in which cells become resistant to elevated temperatures as a result of prior or continuous exposure to hyperthermia. Thermotolerant cells exhibit a decreased slope of the cell survival curve. Recent studies disclosed that thermotolerance developed in rodent tumors and normal tissues as well. Thermotolerance develops during the treatment at a temperature below approximately equal to 43.0 degrees C, or it develops rapidly after the first heat treatment. The decay of thermotolerance is slow and is incomplete over 7 days in many normal tissues, while it appears to be completed in murine tumors. The kinetics of thermotolerance is modified by various factors. In general, the greater the initial heat damage (independently of temperature), the greater is the magnitude of thermotolerance and the longer is the time to reach maximum and the time to decay. Although thermotolerance develops less extensively in cultured cells in low pH medium and the average tumor tissue pH is lower than the normal tissue pH, the magnitude of thermotolerance in tumors thus far examined is at least equal to that in the normal tissues. Data on the interaction between thermotolerance and radiosensitivity are contradictory, although thermotolerance appears to reduce thermal radiosensitization. The kinetics of reduced sensitization is similar to that of thermotolerance. The interaction between chemotherapeutic agents and thermotolerance appears to depend on the drug and the temperature. Experimental data on this topic are still sparse and extensive studies are required.

Effect of 42 degrees C hyperthermia on murine normal and tumor tissues.

The effect of one or two heat treatments at 42.0 degrees C was studied in murine normal and tumor tissues. Early-generation isotransplants of a spontaneous fibrosarcoma, FSa-II tumors, were used. Single-cell suspension was transplanted into the mouse foot. Tumor growth time, the time required for half the treated tumors to reach 1000 cu mm from treatment day was the end point. For normal tissue studies, the foot reaction was scored according to our numerical score system. Hyperthermia was given in a constant temperature water bath. Tumors were treated when they reached an average diameter of 4 (35 cu mm) or 8 mm (270 cu mm). The 4-mm tumor responded poorly to a single heat treatment at 42.0 degrees C, while the 8-mm tumor showed a substantial initial response, followed by the development of thermal resistance. The dose-response curve for the foot reaction was characterized by a large shoulder followed by a linear relationship. Thermal resistance developed in the 8-mm tumor following a continuous treatment of 150 min while in the foot tissue, 800 min were required before the development of thermal resistance. The kinetics of thermal resistance were studied following the first dose of 150 min. Substantial resistance developed in both 4- and 8-mm tumors, as well as in the foot tissue, and reached maximum within 1 day. The decay of thermal resistance in the 8-mm tumor and in the foot was incomplete even at 5 days after the first heat dose, while the analysis was difficult for the 4-mm tumor because of continuous tumor growth. Comparison with treatments at 43.5 degrees C and 45.5 degrees C gave a conclusion that (a) a short single heat treatment of the 8-mm tumor at 42.0 degrees C (below 43.0 degrees C) resulted in a differential response between tumor and foot tissues, but a longer treatment did not; (b) the treatment temperature above 43.0 degrees C was highly recommended; and (c) fractionated heat treatment at 42.0 degrees C was not the choice of treatment for both 4- and 8-mm tumors.

Insignificant tumor bed effect after pretransplantation hyperthermia.

Effect of pretransplantation hyperthermia of tumor bed on tumor growth was studied. Experimental tumors were isotransplants of a fibrosarcoma which arose spontaneously in C3Hf/Sed mice. The pretransplantation hyperthermia was given at 43.5 degrees fro 120 min by immersing the mouse foot into a constant temperature water bath. This treatment resulted in a similar foot reaction to a single gamma-ray dose of 3500 rads, namely, complete epilation or partial moist desquamation. The pretransplantation hyperthermia failed to retard tumor growth, while the concurrent experiment on pretransplantation irradiation demonstrated marked retardation of tumor growth. No retardation was observed when tumor cells were transplanted into the contralateral untreated feet or into the untreated skin.

Effect of hyperglycemia on the thermal response of murine normal and tumor tissues.

The effect of an i.p. injection of glucose on the thermal response of murine tissues was studied. Animal tumors were early generation isotransplants of a spontaneous fibrosarcoma, FSa-II. Tumors were transplanted into the foot pad, and hyperthermia was given by immersing the foot into a constant-temperature water bath. The tumor and normal tissue responses were studied by assays of the time required for half the tumors to reach 1000 cu mm from treatment day and of the treatment time required for one-half of the animals to develop a loss of one toe or greater reaction. The glucose administration enhanced tumor response more substantially than normal tissue response. The enhancement was greater for a large tumor than for a small tumor and also greater at 42.0 degrees than at 45.5 degrees. Presumably, the hyperglycemia induced acidosis which eventually enhanced thermal response. Present results suggested that the hyperglycemia is a potential method to specifically enhance tumor response at elevated temperatures.

Effect of hyperglycemia on thermochemotherapy of a spontaneous murine fibrosarcoma.

The effect of hyperglycemia on the cytotoxic effect of a chemotherapeutic agent was studied at elevated temperature. The seventh generation of a spontaneous C3Hf/Sed mouse fibrosarcoma, FSa-II, was transplanted into the footpads of the same strain of mice. Hyperthermia was given by immersing animal feet into a water bath where 41.5 +/- 0.1 degrees (range) was maintained by a constant temperature circulator. Cyclophosphamide (CY), an alkylating agent, was selected as a test agent. Single i.p. doses of glucose and of CY were given 60 and 30 min before the initiation of hyperthermia. Tumor response was assayed by determining the median tumor growth time (time required for one-half of the treated tumors to reach 1000 cu mm), and the dose-response curve was obtained. Hyperthermia enhanced tumor response to CY. The enhancement was greater when a glucose dose of 10 mg/g was administered before CY and heat treatments. The enhancement ratio, calculated as a ratio of the tumor growth time following CY (200 mg/kg) with heat or with glucose and heat to that following CY alone, was 1.31 or 2.86, respectively. Glucose given at ambient temperature did not enhance the effect of CY. A dose-response curve obtained for a glucose dose with fixed CY (200 mg/kg) and heat (90 min at 41.5 degrees) doses demonstrated that a significant enhancement was obtained following a glucose dose as low as 2 mg/g, suggesting that the glucose enhancement could be safely achieved for human cancer treatment.

Cytocidal and cytostatic ability of Corynebacterium liquefaciens in mouse squamous cell carcinoma in vivo.

The cytostatic and cytocidal action of Corynebacterium liquefaciens was studied in a mouse squamous cell carcinoma in vivo. Kinetic analysis of tumor cells 4 and 8 days after a single i.p. dose of 2.0 mg C. liquefaciens showed a marked prolongation of the mean cell generation time (TG). This prolongation affected most the G1 and, to a lesser extent, the S phases of the cell cycle. The tumor growth factor was decreased, and the mean value of the cell loss factor was increased. Assays to determine the number of tumor cells needed to produce the tumor in one-half of the transplant recipients showed that peritoneal exudate cells collected from mice given injections of C. liquefaciens exerted tumor cell killing that depended on the peritoneal exudate cell tumor:cell ratio. This cell killing was not found with peritoneal exudate cells from normal or proteose peptone-treated mice.

Effect of bleomycin on murine tumor cells at elevated temperatures and two different pH values.

The cytotoxic effect of bleomycin, an antibiotic chemotherapeutic agent, at elevated temperatures was investigated. Single cell suspensions of FSa-II tumor cells were treated at elevated temperatures with or without bleomycin either at pH 7.4 or 6.7. Immediately after treatment, cells were cooled and diluted for lung colony assay. Cyclophosphamide of 200 mg/kg was injected i.p. into the recipient mice 48 h before i.v. injection of tumor cells. Lungs were removed 13 days thereafter and fixed in Bouin's solution. Colonies formed on the surface of each lobe were counted, and the surviving fractions were calculated. Cell survival was determined as a function of treatment time at various temperatures. Survival curves following bleomycin treatment at various temperatures were biphasic. Initial steep portion was followed by a resistant tail. The surviving fractions were reduced to 0.1 within 20 min of treatment at pH 7.4 in the temperature range from 39.0 degrees-43.5 degrees C, and 10 min at pH 6.7. The slope of the resistant tail becomes steeper with increasing temperature, indicating that the cytotoxic effect of bleomycin was enhanced at elevated temperatures. The reciprocal of D0 (treatment time to reduce surviving fraction from 1.0 to 0.37 on the exponential portion of survival curve) of the resistant tail was plotted as a function of the treatment temperature, and activation energy was calculated. This analysis indicates that the enhancement of the cytotoxic effect increases with increasing temperature. However, above 42.5 degrees C, this enhancement appears to be dominated by lethal thermal damage.

Effect of corynebacterium liquefaciens on a C3Hf mouse squamous cell carcinoma.

The antitumor effect of anaerobic Corynebacterium liquefaciens was compared with that of specific immunization. Experimental tumors were fourth or fifth generation isotransplants of a NR-Sl squamous cell carcinoma that arose spontaneously in a C3Hf/He female mouse. Specific immunization failed to exhibit an antitumor effect, whereas a single administration of the bacterium markedly inhibited the growth of the tumor. This growth inhibition was most effective when C. liquefaciens was administered 2 to 4 days before transplantation of tumor cells, but marked inhibition was also observed when this agent was administered after transplantation. The inhibitory effect was independent of dose within a range of 0.1 to 2.0 mg/mouse; a single dose of less than 0.05 mg/mouse did not exhibit antitumor effect. Multiple administrations of large doses, if given with short treatment intervals, were no more effective than one small dose. Multiple doses given at 14-day intervals resulted in marked growth retardation. The dose of cells that produced 50% tumor takes in C. liquefaciens-treated animals was not significantly different from that in nontreated animals, indicating that this bacterium exhibited no lethal effect on the tumor cells studied.

Enhancement by Corynebacterium parvum of the normal and tumor tissue response to hyperthermia.

The effect of Corynebacterium parvum treatment on the response of tumor and normal tissue to hyperthermia (43.5 degrees) was studied. Animals were C3Hf/Sed mice from our defined flora mouse colony. The time at hyperthermia that achieved control of one-half of methylcholanthrene-induced fibrosarcomas and the foot reaction were examined after treatment. C. parvum, if given 3 to 32 days before hyperthermia, enhanced the reaction to local hyperthermia of normal tissue. No enhancement was observed if C. parvum was given after hyperthermia. This enhancement was more dramatic for tumor response resulting in a therapeutic gain factor of congruent to 2.3 (3.7/1.6). Comparative studies on combined Corynebacterium and radiation failed to demonstrate the enhancement to normal tissue.

Suppression of fibrosarcoma metastasis by elevated expression of manganese superoxide dismutase.

A mouse fibrosarcoma cell line (FSa-II), which exhibits low endogenous levels of manganese superoxide dismutase, was transfected with a human manganese superoxide dismutase complementary DNA. Fifty clones were screened for manganese superoxide dismutase activity by the superoxide dismutase activity gel assay. Activity of the positive clones was measured by the nitro blue tetrazolium-reduction assay in the presence of cyanide. Three cell lines exhibiting a range of activity were chosen to be transplanted into syngeneic mice. The results indicated that the metastasis rate for all transfected cells was significantly less than that of control cells.

Enhancement of thermal response of normal and malignant tissues by Corynebacterium parvum.

Further studies were carried out on the combined effects of Corynebacterium parvum and hyperthermia on animal tissues and cultured Chinese hamster ovary cells. Experimental animals were C3Hf/Sed mice derived from our defined flora mouse colony. Tumors were eighth-generation isotransplants of a spontaneous fibrosarcoma, FSa-II. Hyperthermia was given by immersing the mouse foot or culture flasks in the constant temperature water bath. Present experiments include thermal enhancement of C. parvum at different temperatures, effect of the agent on the kinetics of thermal resistance, and the mechanism of the thermal enhancement. The thermal enhancement by C. parvum was independent of temperature in a range between 42.5 and 46.5 degrees, and it increased with decreasing temperature. The analysis of the Arrhenius plot suggested a comparable activation energy for combined treatments and for heat alone between 42.5 and 46.5 degrees. The thermal resistance developed very rapidly in both normal and tumor tissues. Systemic administration of C. parvum failed to modify the kinetics of thermal resistance. Several experiments were attempted in order to disclose the mechanism. A single injection of C. parvum-induced macrophages failed to enhance thermal response of the mouse foot, while 3 daily injections of the macrophages enhanced the response, indicating that the enhancement by C. parvum is at least partly attributed to the C. parvum-induced macrophages. Whole-body irradiation of 6 Gy and/or administration of anti-mouse T-cell serum and histamine failed to inhibit the C. parvum enhancement of thermal response. No thermal enhancement was observed for Chinese hamster ovary cells treated at 43.0 degrees in vitro with C. parvum or thiomersalate , a preservative supplemented in C. parvum, although cytotoxic effect was shown at a high concentration of thiomersalate .

Effect of whole-body hyperthermia on cell survival, metastasis frequency, and host immunity in moderately and weakly immunogenic murine tumors.

The effects of whole-body hyperthermia (WBH) on animal tumors and on metastasis frequency were studied. The tumors were a chemically-induced fibrosarcoma, FSa-I, which is moderately immunogenic and a spontaneously arisen fibrosarcoma, FSa-II, which is very weakly immunogenic. The WBH was given at 42.5 degrees in an incubator which had an auxiliary heater for accurate temperature control. Animal core temperature reached 41.5 degrees in 30 min. The lung colony assay revealed that the WBH for 60 min given at 24 hr after i.v. injection of single cells gave no lethal damage to either FSa-I or -II tumor cells. A significant inhibition of tumor growth was found when large tumors were given three daily WBH treatments. The frequency of lung metastasis was enhanced when large weakly immunogenic FSa-II tumors were treated by WBH, although no increase in the frequency was observed for FSa-I tumors of any size. Local hyperthermia did not significantly increase the metastasis rate of both tumors. These results suggest that the WBH might be useful for a treatment of large immunogenic tumors. However, the WBH is not a choice of treatment for possible micro-metastases.

Enhancement of the thermal response of animal tumors by Corynebacterium parvum.

The effect of Corynecbacterium parvum treatment on the thermal response of animal tumors was studied. Tumors were methylcholanthrene-induced (FSa-II) and spontaneous (FSa-I) fibrosarcomas in C3Hf/Sed mice. C. parvum was given i.v. and was followed by local hyperthermia at 43.5 degrees 3 days later. Cell survival determined by lung colony assays showed that preadministration of C. parvum insignificantly enhanced the thermal response of both tumors. Studies of delay of tumor growth for FSa-II demonstrated that the enhancement ratio decreased with increasing time of treatment and reached a minimum of approximately equal to 1.7. The enhancement ratio for the time at hyperthermia which achieved tumor control in one-half of the treated tumors was 1.7. Together with our previous results on normal tissue responses, the therapeutic gain factor for obtaining 50% tumor control was found to be 1.1 (1.7/1.55) for the weekly immunogenic FSa-II tumor, while it was 2.3 for moderately immunogenic FSa-I as reported previously.

Effect of thermochemotherapy (combined cyclophosphamide and hyperthermia) given at various temperatures with or without glucose administration on a murine fibrosarcoma.

The effect of combined cyclophosphamide (CY) and heat treatments on a murine tumor was studied at various temperatures. FSa-II tumors, the early generation isotransplants of a spontaneous fibrosarcoma in a C3Hf/Sed mouse, were used. A single cell suspension was transplanted into the animal foot. Hyperthermia was given by immersing animal feet into a water bath maintained at a desired temperature +/- 0.1 degrees C. An average diameter of the tumor at the time of treatment was 4 mm. The tumor growth time, the time required for one-half of the treated tumors to reach 1000 mm3, was the end point. Hyperthermia enhanced the effect of CY at test temperatures ranging from 40.5 degrees - 44.5 degrees C. The enhancement was independent of the temperature when CY was administered 30 min before the beginning of hyperthermia. However, the enhancement was most substantial at temperatures of 40.5 degrees -42.5 degrees C when CY was administered immediately before hyperthermia. The most effective timing of the CY administration was immediately before hyperthermia. The glucose administered 60 min before hyperthermia enhanced the effect of combined CY and hyperthermia when CY was given 30 min before heating. This enhancement was lost when CY was given immediately before hyperthermia. The CY dose response curves at elevated temperatures were downward concave, which may indicate the presence of a CY- and heat-resistant cell population in the tumor. Implications of these observations in clinical hyperthermia were discussed.

Expression of manganese superoxide dismutase reduces tumor control radiation dose: gene-radiotherapy.

This study investigated the in vitro and in vivo radiation response of tumor cells transfected with human manganese superoxide dismutase (MnSOD) cDNA. A major objective was to test the potential tumor suppressive effect of MnSOD in vivo. Tumor cells studied were an in vitro line derived from a murine spontaneous fibrosarcoma, FSa-II, which expressed an undetectable MnSOD activity. These cells were transfected with pSV2-NEO plasmid (NEO line) or cotransfected with MnSOD plasmid plus pSV2-NEO plasmid (SOD lines) as described previously. The cell lines used were SOD-L and SOD-H, which expressed, respectively, low and high MnSOD activities after transfection, and NEO and parental FSa-II controls. Both SOD-L and SOD-H cell lines were slightly more resistant to ionizing radiation than were the two control cell lines when irradiated in vitro in the presence of oxygen. The dose-modifying factors calculated at the survival level of 0.01 were 1.13 and 1.15 for the SOD-L and SOD-H cells, respectively. To investigate potential tumor suppressive effects, animal tumors of 4 mm diameter were irradiated in vivo under hypoxic conditions, and the radiation dose to control one-half of the irradiated tumors (TCD50) was determined for each tumor. The TCD50S obtained on the basis of the tumor control rate in 120 days after irradiation were substantially lower for the SOD-H and SOD-L tumors compared to the NEO tumors. They were 22.9, 28.6, and 47.5 Gy for SOD-H, SOD-L and NEO tumors, respectively. To analyze these data, survival curves were obtained for hypoxic cells by irradiating NEO and SOD-H tumors under hypoxic conditions in vivo and assaying in vitro. Analysis of these curves suggests that the decrease in the TCD50S of SOD tumors is attributable to the reduced tumorigenicity in these tumors. The hypoxic cell survival curves also showed that SOD did not protect cells from radiation in the absence of oxygen. Electron microscopy showed no morphological differences between these cells. These results suggest that the fraction of tumorigenic cells could be reduced by expression of MnSOD, resulting in a substantial decrease in the TCD50.

Lack of thermal inhibition of radiation damage repair in the late-appearing foot reaction.

Our previous study on early- and late-appearing murine foot reactions following combined hyperthermia and irradiation suggested that hyperthermia may not inhibit repair of sublethal and/or potentially lethal radiation damage for the late-appearing reaction. A series of split dose experiments was performed by using C3Hf/Sed mouse foot reaction, which showed both early and late responses in the same tissue. Hyperthermia given in a 43.5 degrees C water bath for 45 min inhibited radiation damage repair in the early-appearing reaction, but was not able to modify repair in the late-appearing reaction. The failure of thermal inhibition of radiation damage repair in the late-appearing reaction was observed regardless of the sequence of heat and irradiation. Complete repair appeared to require approximately 9 hr. Although it is unknown whether radiation damage repair can be completely inhibited in all late-responding normal tissues, the reduction in thermal repair inhibition in some late-responding tissues may be an advantage of "heat prior to irradiation" treatment over radiation alone.

Late reaction following twice-a-day irradiations in the murine foot: possible repopulation or consequential late effect.

The effect of twice-a-day irradiation on the foot reaction was studied in C3Hf/Sed mice. A numerical scoring system was used to evaluate the foot reaction that became visible shortly after irradiation. Peak reaction occurred on the 21st to 23rd day and reappeared after approximately the 200th postirradiation day. These reactions are called early- and late-appearing reactions, respectively. Animals studied for early-appearing reactions were continuously scored for more than 600 days after irradiation. The late-appearing reaction increased continuously or remained constant, but never decreased during the course of the experiments. Animal feet were irradiated with a fraction size from 1.0 to 5.0 Gy twice-a-day daily with a treatment interval of 6 and 18 hours, and varying numbers of fractions were given. A top-up dose of 20 Gy was given as the last dose. The late-appearing foot reaction following a fraction size of 1.5 Gy or greater increased with increasing total dose. However, the increase in the late reaction score with increasing total dose was trivial following multiple doses with a fraction size of 1.0 Gy, suggesting a possible repopulation during prolonged irradiation or that the observed reaction was a consequential late effect. The Fe-plot based on doses which induced fibrosis in one-half of the irradiated animals, showed an alpha/beta ratio of 6.57 +/- 0.62 Gy, and the presence of a breaking point at approximately 1.5 Gy. The alpha/beta ratios calculated by Joiner's method and Thames direct analysis were identical. The slope of the Fe-plot below 1.5 Gy was significantly steeper than that above 1.5 Gy.