Evaluation of Usefulness of Yeast-Based Biological Phantom and Preliminary Study for Verification of Hypoxic Effect of Flash Radiotherapy

PURPOSE/OBJECTIVE(S)

As a basic hypothesis for the effectiveness of flash radiation therapy, the effect of preserving normal tissue during flash radiation is due to the instantaneous chemical depletion of oxygen. A yeast-based biological phantom was created to verify the hypoxic effect of flash radiation therapy. A study to upgrade the previously developed X-Band LINAC to a flash irradiation mode is in progress, and a preceding study is conducted to evaluate the usefulness of a yeast-based biological phantom manufactured by analyzing the change in oxygen by irradiating a high dose in a general radiation therapy device.

MATERIALS/METHODS

Freeze-dried yeast sample (Saccharomyces cerevisiae, S288C) is activated and sub-cultured. For mass production of yeast samples, yeast culture medium is prepared by adding yeast colonies to the ypd medium. This study was conducted to verify the hypoxic effect among the biological mechanisms that occur during flash radiation therapy at the basic stage, and the oxygen concentration change during general radiation irradiation was measured in real time using a DO (Dissolved oxygen) meter and fiber optic sensor designed to do that. To prevent scatter, which is a concern during flash irradiation, the fiber form was used, and precise experiments are possible as a non-invasive oxygen concentration measurement method. Based on 10MV of general radiation therapy device, high-dose radiation of 500-10,000 cGy is irradiated to measure real-time oxygen concentration change.

RESULTS

As a result of irradiation with high-dose (500-10,000 cGy) radiation of general LINAC, it was confirmed that the oxygen concentration of the yeast culture medium decreased by 5.7-63.2%, and the usefulness of the biological phantom fabricated based on the yeast culture medium was evaluated.

CONCLUSION

Prior to the analysis of oxygen concentration change in yeast cells during X-Band LINAC flash irradiation, a preliminary study was conducted at a high dose in a general LINAC to obtain a significant result of oxygen concentration change and confirm the usefulness of the yeast-based biological phantom. Prior research was conducted and verified as a general irradiation experiment using a yeast-based biological phantom manufactured based on a DO meter and a fiber optic oxygen sensor. After irradiation with high-dose radiation, the oxygen concentration of the yeast culture medium was measured 5 times, and it was confirmed that there was a change in oxygen concentration of 5.7-63.2%, verifying the usefulness and stability of the biological phantom. The usefulness of the yeast-based biological phantom for high doses was confirmed, and it is expected that the usefulness of the biological phantom for flash radiation can be verified by additionally measuring the change in oxygen concentration of the biological phantom according to the high dose rate in the future.

Prognostic value of pretreatment (18)F-FDG PET-CT in radiotherapy for patients with hepatocellular carcinoma

Purpose

The purpose of this study was to investigate the predictable value of pretreatment ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) in radiotherapy (RT) for patients with hepatocellular carcinoma (HCC) or portal vein tumor thrombosis (PVTT).

Materials and Methods

We conducted a retrospective analysis of 36 stage I-IV HCC patients treated with RT. ¹⁸F-FDG PET-CT was performed before RT. Treatment target was determined HCC or PVTT lesions by treatment aim. They were irradiated at a median prescription dose of 50 Gy. The response was evaluated within 3 months after completion of RT using the Response Evaluation Criteria in Solid Tumors (RECIST). Response rate, overall survival (OS), and the pattern of failure (POF) were analyzed.

Results

The response rate was 61.1%. The statistically significant prognostic factor affecting response in RT field was maximal standardized uptake value (maxSUV) only. The high SUV group (maxSUV ≥ 5.1) showed the better radiologic response than the low SUV group (maxSUV < 5.1). The median OS were 996.0 days in definitive group and 144.0 days in palliative group. Factors affecting OS were the %reduction of alpha-fetoprotein (AFP) level in the definitive group and Child-Pugh class in the palliative group. To predict the POF, maxSUV based on the cutoff value of 5.1 was the only significant factor in distant metastasis group.

Conclusion

The results of this study suggest that the maxSUV of ¹⁸F-FDG PET-CT may be a prognostic factor for treatment outcome and the POF after RT. A %reduction of AFP level and Child-Pugh class could be used to predict OS in HCC.

Significance of low-dose radiation distribution in development of radiation pneumonitis after helical-tomotherapy-based hypofractionated radiotherapy for pulmonary metastases

Hypofractionated radiotherapy (HRT) is now commonly used for pulmonary malignancies, since a tumoricidal dose can be accurately delivered to the target without a consequential dose to adjacent normal tissues. However, radiation pneumonitis (RP) is still a major problem after HRT. To determine the significant parameters associated with developing RP, we retrospectively investigated data from patients with lung metastases treated with HRT using helical tomotherapy. A total of 45 patients were included in the study and the median age was 53 years old. The median prescriptive doses were 50 Gy to the internal target volume and 40 Gy to the planning target volume in 10 fractions over 2 weeks. RP was diagnosed by chest X-ray or computed tomography after HRT, and its severity was determined by CTCAE version 4.0. The incidence of symptomatic RP was 26.6%. Univariate analysis indicated that mean lung doses, V5, V10, V15, V20 and V25 were associated with the development of symptomatic RP (P < 0.05). However, multivariate analysis indicated that only V5 was associated with the development of symptomatic RP (P = 0.019). From the ROC curve, V5 was the most powerful predictor of symptomatic RP, and its AUC (area under curve) was 0.780 (P = 0.004). In addition, the threshold value of V5 for the development of symptomatic RP was 65%. A large distribution of low-dose radiation resulted in a higher risk of lung toxicity. So, to prevent symptomatic RP, it is recommended that the V5 be limited to <65%, in addition to considering conventional dosimetric factors. However, further clinical study must be undertaken in order to confirm this result.

Supine linac treatment versus tomotherapy in craniospinal irradiation: planning comparison and dosimetric evaluation

Craniospinal irradiation (CSI) is the standard treatment of primary intracranial tumour with risk of leptomeningeal dissemination. However, supine setup field-in-field technique does not need inter-fractional junction shift. Recently, the studies of CSI with tomotherapy showed excellent target coverage and tolerable normal organ dose in paediatric patients. The planning comparison and dosimetric difference between conventional radiotherapy and tomotherapy are presented. Three patients with central nervous system germinoma received supine CSI treatment. Normal tissue complication probability calculation was performed for parotid gland, kidney, lens, small bowel, ovary and testis. Homogenous vertebral body coverage for tomotherapy compared with conformal radiotherapy was found. The mean dose to each parotid gland decreased by 7.3 and 10 Gy, respectively, with tomotherapy. The volume of oesophagus and small bowel receiving >10 Gy was significantly lower. The V2, V5, V10 and V20 of the lungs are 81.6, 12.4, 2.3 and 0 % with tomotherapy. Tomotherapy showed excellent homogenous dose distribution through the craniospinal axis (PTV) and higher conformity index.

Transferring AAC intervention to the home

PURPOSE

To evaluate the acquisition of AAC skills during an initial clinical trial and assess subsequent transfer of the training to the home setting.

METHOD

A 12-year-old male with autism was first seen in a clinical setting to establish the use of a voice-output communication device. After learning to use the device to request access to preferred objects in the clinical trial, the intervention was transferred to the home. Follow-up with the parent was conducted via e-mail and telephone. Videotapes were made of initial home-based sessions to enable evaluation of the participant's progress.

RESULTS

The programme was successful in teaching the participant to use a portable AAC device to make requests during the clinical trial and then in two home-based activities.

CONCLUSION

An initial clinical trial with follow-up support for parents may be an efficient method for beginning AAC intervention and transferring the training procedures to the home setting.

Loss of mitochondrial membrane potential and caspase activation enhance apoptosis in irradiated K562 cells treated with herbimycin A

PURPOSE

We previously reported that herbimycin A (HMA) alters the mode of cell death of K562 cells induced by radiation and enhanced their radiosensitivity. In the present study, we explored the apoptosis-inducing activity of HMA and the fundamental mechanism via which it regulates radiation-induced cell death.

MATERIALS AND METHODS

Chronic myelogenous leukemia (CML) cell line K562 was used. For X-irradiation and drug treatment, cells were plated at approximately 2x10(5) cells/ml. Exponentially growing cells were treated with 10 Gy of X-ray using a 6-MeV X-ray machine at a dose rate of 200-300 cGy/min. The cells were treated with 0.25 microM HMA immediately after irradiation and HMA remained for the entire culture period. The modes of cell death were discriminated by morphological changes, analysis of cell cycle, analysis of the mitochondrial events, and the expression of apoptosis-related proteins.

RESULTS

Our data demonstrates that radiation induced a significant time-dependent increase of cell death and failed to sustain a prolonged G2 arrest in K562 cells. Radiation-induced cell death caused the accumulation of cyclinB1 and weak nuclear fragmentation, suggesting a mitotic catastrophe. This mitotic catastrophe was dependent upon the mitochondrial permeability transition pore (PTP) opening and was independent of caspase-3. In contrast, K562 cells treated with radiation and HMA had an accelerated cell death and induced a p53-independent apoptosis. This apoptotic pathway was dependent upon an initial hyperpolarization of the mitochondrial inner membrane, following the release of cytochrome c and subsequent caspase-3 activation.

CONCLUSIONS

Two mechanisms of radiation-induced cell death in K562 cells, mitotic catastrophe and apoptosis, are regulated through distinct pathways, mitochondria and caspase-independent and -dependent, respectively. The findings of this study may provide new insights into improving the efficiency of radiotherapy in CML patients.

Preparation of doxorubicin-containing chitosan microspheres for transcatheter arterial chemoembolization of hepatocellular carcinoma

A new form of doxorubicin hydrochloride (DRH)-containing chitosan microspheres (CMs) was prepared by employing an expanding-loading-shrinking (E-L-S) process. One hundred mg of pre-formed CMs were soaked in absolute ethanol and then placed in reduced pressure (the expanding process). Ten mg of DRH (2 mg ml(-1)) were added into the expanded CMs (the loading process). Next the microspheres were freeze-dried (the shrinking process). As a result of this E-L-S process, 10% (w/w) DRH-containing CMs (DRH-CM) were made. During 7 days, 22.6% of the DRH was observed to be released on the in vitro drug release study. In addition, these new DRH-CMs could be used for transcatheter arterial chemoembolization (TACE) procedure in VX2 hepatic tumour models of rabbit and the anti-tumour effects of DRH-CMs were investigated. On the post-CT scan 7 days after the TACE, total infarctions of the VX2 tumour were observed in 5 rabbits among the 6 total rabbits.

A plant growth promoting rhizobacterium, Paenibacillus polymyxa strain GBR-1, suppresses root-knot nematode

Exposure of root-knot nematode, Meloidogyne incognita to various concentrations (5-100%) of culture filtrate of Paenibacillus polymyxa GBR-1 under in vitro conditions significantly reduced egg hatch and caused substantial mortality of its juveniles. The increase in the exposure durations of juveniles to culture filtrate and its concentrations increased the mortality rate. Similarly, higher concentrations increased its inhibitory effect on egg hatch. In higher concentrations (25-100%) egg hatch was inhibited by 84-91% after 2 days of exposures as compared to control in sterile distilled water. Application of various concentrations of culture filtrate extract or bacterial suspension of P. polymyxa GBR-1 into potting soil infested with 2000 J2 of M. incognita, reduced the root galling and nematode populations and increased tomato plant growth and root-mass production compared with untreated control (P< or = 0.05). The beneficial effect of P. polymyxa GBR-1 into potted soil increased exponentially with the increase in dose concentrations. Root gall index was reduced from 4.8 to 1.4 and 1.8 when potting soil was treated with 10% concentrations of culture filtrate extract and bacterial suspension, respectively, compared with untreated control. Application of bacterial suspension of P. polymyxa GBR-1 into potted soil at 3 day pre-inoculation of nematode was the most effective followed by simultaneously and at 2 days post-inoculation; as root galling was reduced by 62.5%, 58.3% and 50.0%, respectively, compared with untreated control.

Comparison of 5-fluorouracil/leucovorin and capecitabine in preoperative chemoradiotherapy for locally advanced rectal cancer

PURPOSE

To describe our experience with a bolus injection of 5-fluorouracil and leucovorin (FL) vs. capecitabine in terms of radiologic and pathologic findings in preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer.

METHODS

The study enrolled 278 patients scheduled for preoperative CRT using two protocols with different chemotherapeutic regimens. Pelvic radiotherapy (50.4 Gy) was delivered concurrently with FL (n = 145) or capecitabine (n = 133). Surgery was performed 6 weeks after CRT completion. Tumor responses to CRT were measured using both radiologic and pathologic examination. Magnetic resonance volumetry was performed at the initial workup and just before surgery after completion of preoperative CRT. Post-CRT pathology tests were used to determine tumor stage and regression.

RESULTS

Radiologic examination showed that tumor volume decreased by 68.2% +/- 20.5% in the FL group and 68.3% +/- 22.3% in the capecitabine group (p = 0.970). Postoperative pathologic T stage determination showed that downstaging occurred in 44.3% of FL and 49.9% of capecitabine patients (p = 0.571). The tumor regression grades after CRT were Grade 1 (minimal response) in 22.6% and 21.0%, Grade 2 (moderate response) in 53.2% and 50.0%, Grade 3 (near-complete response) in 12.9% and 12.9%, and Grade 4 (complete response) in 11.3% and 16.1% of the FL and capecitabine groups, respectively (p = 0.758).

CONCLUSION

In the present study, the radiologic and pathologic findings did not reveal significant differences in short-term tumor responses between preoperative FL and capecitabine CRT for locally advanced rectal cancer. Long-term results and a prospective randomized trial are needed.

The role of radiation therapy for the extramammary paget's disease of the vulva ; experience of 3 cases

We have experienced three cases of extramammary Paget's disease (EMPD) of the vulva that received radiation therapy (RT). Here, we analyze the efficacy of RT and include a literature survey.Three patients with EMPD of the vulva were treated with curative RT between 1993 and 1998. One of the patients had associated underlying adenocarcinoma of the vulva. The total doses of radiation administered were 54~78 Gy/6~8 weeks. Radiation fields encompassed 2 to 3 cm outer margins free from all visible disease including or not including the inguinal area using a 9 MeV electron or a 6 MV photon beam. Follow-up durations after radiotherapy were 0.6~11 years. Complete response was obtained in all three patients. Marginal failure occurred in one patient, and another patient with underlying adenocarcinoma treated by vulvectomy with bilateral inguinal lymph node dissection followed by external RT showed no relapse. Radiation induced side effects were transient acute confluent wet desquamation in the treated area resulting in mild late atrophic skin changes.Although surgery is currently considered the preferred primary treatment for EMPD, it has a high relapse rate due to the multifocal nature of the disease. We conclude that RT is of benefit in some selected cases of EMPD.

Large-scale growth and taxane production in cell cultures of Taxus cuspidata (Japanese yew) using a novel bioreactor

 A novel type of bioreactor was successfully developed for the production of taxol and its precursors by culturing cells of Taxus cuspidata (Japanese yew) on a pilot-scale. Rapidly growing cell lines were selected from callus cultures derived from immature embryos of yew. The cells were inoculated in 20-l capacity bioreactors of different types to test the growth performance. The models of small-scale bioreactors incorporated in this study included a balloon-type bubble bioreactor (BTBB), a bubble-column bioreactor (BCB), a BCB with a split-plate internal loop, a BCB with a concentric draught-tube internal loop, a BCB with a fluidized bed bioreactor, and two different models of stirred tank reactors. Among the reactors, BTBB appeared to be the most efficient in promoting cell growth. The doubling time of cell growth in BTBB was 12 days with a 30% inoculation cell density. The optimum time for medium replacement or feeding was 12-15 days after inoculation as determined by monitoring both the levels of sugars and medium conductivity. When yew tree cells were grown in different sizes (100-500-l) of BTBBs, more than 70% cell viability was recorded at the time of harvest. The growth pattern of the cells in the pilot-scale BTBB appeared to be the same as that of cells in the 20-l bioreactors. Approximately 3 mg/l of taxol and 74 mg/l total taxanes were obtained after 27 days of culture.

Development of three-dimensional descriptors represented by tensors: free energy of hydration density tensor

In order to describe the degree of interaction of a molecule with its environments by descriptors, several three-dimensional descriptors have been proposed. With the physical properties calculated around a molecule, scalar, vector, and tensor (zeroth, first, and second moments) of the physical properties were calculated and were used as descriptors for calculating the similarity index between the molecules. The tensors contain the information on the spatial distribution of those physical properties around the molecule. Hydration Free Energy Density (HFED) proposed by No et al. was used to calculate HFED tensor. The descriptors were used for the similarity index calculations between substituted benzenes and between lead compounds of HIV-1 protease inhibitors. The substituted benzenes are grouped according to the similarity indices. The grouping seems reasonable from the viewpoint of a chemical sense. The lead fragments of the HIV-1 protease inhibitors have a high similarity among themselves though their chemical formulas are not very similar, the lead fragments are diverse. Although the chemical formulas are diverse, the spatial distribution of the physical properties around the molecules is similar. The descriptors have high discriminating power in the similarity calculation between the molecules.

Changes in the evolution of the antigenic profiles and morphology during coccoid conversion of Helicobacter pylori

OBJECTIVES

The significance of the coccoid forms of H. pylori is still controversial and the questions of whether these forms are viable and infective or degenerative are still open. We induced conversion from rod to coccoid forms and studied morphological changes and antigenic evolutions during this conversion and, thereby, elucidated the viability of coccoid forms.

METHODS

The H. pylori strain (C001) used for Western blotting was isolated from the patient with gastric cancer. The antigenic evolution during coccoid conversion of H. pylori was studied by Western blotting, using different sera from thirty patients known to be culture positive. These sera were used to reveal the total antigens of the strain cultured for 2 days (100% rod) and 15 days (> 99% coccoid). After SDS-PAGE, with 10% separating gel of total antigens (rod and coccoid), transblotting (Trans-Blot electrophoretic cell, Bio-Rad) was taken onto a nitrocellulose membrane (Bio-Rad). Then, the blots, with human sera diluted at 1/100, were developed with color reaction by goat serum anti-human IgG with alkaline phosphatase and BCIP.

RESULTS

The antigenic profiles were not changed in 46.7% (14/30 cases) and were changed in 53.3% (16/30 cases) during coccoid conversion. Antigenic fractions changed during coccoid conversion were protein band at 120 kDa and band at 35 kDa, and were not detected in coccus forms. The rest of the profiles were identical between rod and coccoid forms. The protein which disappeared include CagA (120 kDa) and porin, or adhesin (35 kDa). The morphological changes during coccoid conversion were U shaped at day 7, doughnut shaped at day 9 and full coccoid at day 15.

CONCLUSIONS

The results showed that coccoid forms of H. pylori retain cellular structures similar to rod form, and some of the antigens (CagA and porin) disappeared during coccoid conversion. Therefore, coccoid form might be viable and represent one of the stages of H. pylori biological cycle.

In vitro shoot regeneration from leaf mesophyll protoplasts of hybrid poplar (Populus nigra x P. maximowiczii)

Protoplasts were isolated from leaf mesophyll of hybrid poplar (Populus nigra X P. maximowiczii) with a mean yield of 10.4 x 10(6) protoplasts per g fresh weight using 2.0% Cellulase 'Onozuka' R-10, 0.8% Macerozyme R-10, 1.2% Hemicellulase, 2.0% Driselase, and 0.05% Pectolyase Y-23 with CPW salts solution containing 0.6 M mannitol, 0.002 M DTT, 3 mM MES at pH 5.6. A liquid plating method produced the highest frequency of dividing protoplasts (48.6%) using an MS medium without NH4NO3. The highest percent of colony formation was 22.8%, produced with fabric supported semi-solid (0.5% w/v) agar plating method using the same culture medium. Growing cell colonies and/or micro-calli were transferred to a fresh semisolid agar medium containing 0.44 μM BAP and 9.0 μM 2,4-D. Multiple shoots were produced from protoplast-derived callus after culture on MS medium containing 6.8 μM zeatin. After root induction on half-strength MS medium that lacked growth regulators, shoots were transferred to pots containing artificial soil mix.

Plant regeneration capacity of callus derived from leaf, stem, and root segments of Populus alba L. x P. grandidentata Michx

Expiants for establishing callus cultures originated from in vitro cultured hybrid poplar (Populus alba L. X P. grandidentata Michx.). Plant regeneration was achieved from established callus cultures derived from stem internodes (SI), leaf discs (LD), and root segments (RS). Shoot regeneration from callus occurred within 4 weeks of culture on most of the media tested. Frequency of shoot formation was greatly increased by subculturing the selected organogenic calli on regeneration media. The highest rate of multiple shoot formation (an average number of 7/SI, 11/LD, and 8/RS) was obtained by using 0.05 μM IBA in combination with 22.5 μM 2iP, 22.5 μM zeatin, and 12.5 μM 2iP, respectively. Regenerated shoots were easily rooted in polyterra(™) peat plugs in transparent plastic boxes. The rooted plantlets were subsequently transferred to pots containing an artificial potting mix.

Actinobacillus actinomycetemcomitans serotypes and leukotoxicity in Korean localized juvenile periodontitis

Actinobacillus actinomycetemcomitans is though to play an important role in the pathogenesis of localized juvenile periodontitis (LJP). Preliminary data suggested that the serotype distribution of A. actinomycetemcomitans in Korea and the United States differ. This study evaluated A. actinomycetemcomitans prevalence, serotype distribution, and leukotoxicity in Korean LJP patients by culture, enzyme-linked immunosorbent assay, indirect immunofluorescence, and lactate dehydrogenase release from polymorphonuclear leukocytes exposed to A. actinomycetemcomitans. A. actinomycetemcomitans occurred in 75% of LJP lesions and 6% of normal sites with approximately equal distribution of serotype a, b, and c. Single serotypes were isolated from nine patients while three patients harbored two serotypes either in the same or different disease sites. A. actinomycetemcomitans leukotoxicity occurred in 22% isolates with a 69% prevalence. Individual sites harbored both leukotoxic and non-leukotoxic strains with no serotype association. The distribution of serotypes and leukotoxic strains of A. actinomycetemcomitans in Korean LJP patients differed from those reported in the United States. This suggests that serotype b may not be more important in the pathogenesis of LJP.

Regeneration of plantlets from cell suspension culture derived callus of white poplar (Populus alba L.)

Friable calli derived from the stem tissues of Populus alba were used to establish cell suspension cultures which were characterized for in vitro growth and regeneration capacity. Suspended cells and callus recovered from these cells were maximal on a fresh weight basis using MS liquid medium containing 0.44 μM BAP and 4.52 μM 2,4-D. Shoot regeneration from the recovered callus was observed within 30 to 40 days of culture. The number of shoots was increased by subculturing the shoot-forming callus 2 to 3 times on MS medium supplemented with 19.7 μM 2iP and 0.05 μM IBA. Regenerated shoots were easily rooted on half-strength MS medium lacking growth regulators, and the plantlets were transferred to pots containing vermiculite for greenhouse growth.