Induction of apoptotic cell DNA fragmentation in human cells after treatment with hyperthermia

Application of nanoparticles in cancer therapy with an emphasis on cell cycle

Owing to their unique characteristics, nanoparticles (NPs) could be incorporated into valuable therapeutic modalities for different diseases; however, there are many concerns about risk factors in human applications. NPs carry therapeutic chemicals that could improve the outcome of cancer therapies. Nowadays, NPs are being recognized as important and strategic agents in treatment of several disorders due to their unique properties in targeting malignant cells in tumor sites. Numerous investigations have shown that the majority of chemotherapeutic agents can be modified through entrapment in submicron colloidal systems. Still, there are problems and limitations in application of NPs in cancer therapy. The aim of the present study is to focus on potential NPs usage in cancer treatment with an emphasis on the cell cycle of malignant cells.

Advances in study of the sequence of lung tumor biopsy and thermal ablation

Percutaneous thermal ablation is an important treatment for lung cancer and is widely used in hospitals. Puncture biopsy is generally required for pathological diagnosis before or after thermal ablation. Pathological diagnosis provides both evidence of benign and malignant lesions for ablation therapy and is of important significance for the next step in disease management. Furthermore, the sequence of ablation and biopsy affects the accuracy of pathological diagnosis, the complete ablation rate of thermal ablation, and incidence of surgery‐related complications. Ultimately, it may affect the patient's benefit from local treatment. This article reviews the research progress of traditional asynchronous biopsy followed by ablation, the emerging methods of synchronous biopsy followed by ablation, and synchronous ablation followed by biopsy in the last decade.

Key points

The sequence of ablation and biopsy affects the accuracy of pathological diagnosis, the complete ablation rate of thermal ablation, and the incidence of surgical‐related complications.

This article reviewed the recent 10 years' literature on the surgical sequence of biopsy and ablation for lung tumors, the advantages, disadvantages and indications of different orders were analyzed.

A repertoire of biomedical applications of noble metal nanoparticles

The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community. In this feature article, we highlight recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing.

Pathologic Diagnosis and Genetic Analysis of a Lung Tumor Needle Biopsy Specimen Obtained Immediately After Radiofrequency Ablation

PURPOSE

To evaluate the possibility of pathologic diagnosis and genetic analysis of percutaneous core-needle biopsy (CNB) lung tumor specimens obtained immediately after radiofrequency ablation (RFA).

MATERIALS AND METHODS

Patients who underwent CNB of lung tumors immediately after RFA from May 2013 to May 2016 were analyzed. There were 19 patients (8 men and 11 women; median age, 69 years; range, 52-88 years) and 19 lung tumors measuring 0.5-2.6 cm (median, 1.6 cm). Thirteen tumors were solid, and 6 were predominantly ground-glass opacity (GGO) on computed tomography. All specimens were pathologically examined using hematoxylin and eosin (H&E) staining and additional immunostaining, as necessary. The specimens were analyzed for EGFR and KRAS genetic mutations. The safety and technical success rate of the procedure and the possibility of pathologic diagnosis and genetic mutation analysis were evaluated.

RESULTS

Major and minor complication rates were 11% (2/19) and 53% (10/19), respectively. Tumor cells were successfully obtained in 16 cases (84%, 16/19), and technical success rate was significantly lower for GGO-dominant tumors (50%, 3/6) compared with solid lesions (100%, 13/13, p = 0.02). Pathologic diagnosis was possible in 79% (15/19) of cases based on H&E staining alone (n = 12) and with additional immunostaining (n = 3). Although atypical cells were obtained, pathologic diagnosis could not be achieved in 1 case (5%, 1/19). Both EGFR and KRAS mutations could be analyzed in 74% (14/19) of the specimens.

CONCLUSION

Pathologic diagnosis and genetic analysis could be performed even for lung tumor specimens obtained immediately after RFA.

Physical mechanism and modeling of heat generation and transfer in magnetic fluid hyperthermia through Néelian and Brownian relaxation: a review

Current clinically accepted technologies for cancer treatment still have limitations which lead to the exploration of new therapeutic methods. Since the past few decades, the hyperthermia treatment has attracted the attention of investigators owing to its strong biological rationales in applying hyperthermia as a cancer treatment modality. Advancement of nanotechnology offers a potential new heating method for hyperthermia by using nanoparticles which is termed as magnetic fluid hyperthermia (MFH). In MFH, superparamagnetic nanoparticles dissipate heat through Néelian and Brownian relaxation in the presence of an alternating magnetic field. The heating power of these particles is dependent on particle properties and treatment settings. A number of pre-clinical and clinical trials were performed to test the feasibility of this novel treatment modality. There are still issues yet to be solved for the successful transition of this technology from bench to bedside. These issues include the planning, execution, monitoring and optimization of treatment. The modeling and simulation play crucial roles in solving some of these issues. Thus, this review paper provides a basic understanding of the fundamental and rationales of hyperthermia and recent development in the modeling and simulation applied to depict the heat generation and transfer phenomena in the MFH.

Diagnostic Ability of Percutaneous Needle Biopsy Immediately After Radiofrequency Ablation for Malignant Lung Tumors: An Initial Experience

PURPOSE

To evaluate the safety and diagnostic ability of percutaneous needle biopsy performed immediately after lung radiofrequency ablation (RFA).

MATERIALS AND METHODS

From May 2013 to April 2014, percutaneous needle biopsy was performed immediately after RFA for 3 patients (2 men and 1 woman, aged 57-76 years) who had lung tumors measuring 1.3-2.6 cm in diameter. All patients had prior history of malignancy, and all tumors were radiologically diagnosed as malignant. Obtained specimens were pathologically classified using standard hematoxylin and eosin staining.

RESULTS

We completed three planned sessions of RFA followed by percutaneous needle biopsy, all of which obtained tumor tissue that could be pathologically diagnosed. Two tumors were metastatic from renal clear cell carcinoma and rectal adenocarcinoma, respectively; one tumor was primary lung adenocarcinoma. There was no death or major complication related to the procedures. Although pneumothorax occurred in two patients, these resolved without the need for aspiration or chest tube placement. Tumor seeding was not observed, but 21 months after the procedure, one case developed local tumor progression that was treated by additional RFA.

CONCLUSION

Pathologic diagnosis was possible by needle biopsy immediately after RFA for lung tumors. This technique may reduce the risks and efforts of performing biopsy and RFA on separate occasions.

Role of iron oxide core of polymeric nanoparticles in the thermosensitivity of colon cancer cell line HT-29

PURPOSE

In this study the effect of PLGA polymeric nanoparticles as a 5-fluorouracil (5-FU) carrier with and without iron oxide core and hyperthermia were investigated on the level of DNA damage in a spheroid culture model of HT-29 colon cancer cell lines by alkaline comet assay.

MATERIALS AND METHODS

First, HT-29 colon cancer cells were cultured in vitro as spheroids with a mean diameter of 100 µm. The spheroids were then treated with different concentrations of 5-FU or nanoparticles as 5-FU carriers with and without an iron oxide core for one volume-doubling time of the spheroids (71 h) and hyperthermia at 43 °C for 1 h. Finally, the effect of treatment on viability and level of DNA damage was examined using trypan blue dye exclusion assay and alkaline comet assay, respectively.

RESULTS

Results showed that hyperthermia in combination with 5-FU or nanoparticles as 5-FU carriers significantly induced the most DNA damage as compared with the control group. The extent of DNA damage following treatment with 5-FU-loaded nanoparticles combined with hyperthermia was significantly more than for 5-FU combined with hyperthermia. In comparison to the effect of 5-FU-loaded nanoparticles with the iron oxide core and 5-FU-loaded nanoparticle without the iron oxide core, the nanoparticles with the iron oxide core combined with hyperthermia induced more DNA damage than the nanoparticles without the iron oxide core.

CONCLUSIONS

According to this study, hyperthermia is a harmful agent and nanoparticles are effective delivery vehicles for drugs into colon cancer cells. The iron oxide filled nanoparticles increased the effect of the hyperthermia. All these factors have a significant role in the treatment of colorectal cancer cells.

Evaluation of DNA damage and antioxidant system induced by di-n-butyl phthalates exposure in earthworms (Eisenia fetida)

Di-n-butyl phthalates (DBP) are recognized as ubiquitous contaminants in soil and adversely impact the health of organisms. The effect of DBP on the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT), malondialdehyde (MDA) content and DNA damage were used as biomarkers to analyze the relationship between DNA damage and oxidative stress and to evaluate the genotoxic effect of DBP on earthworms (Eisenia fetida). DBP was added to artificial soil in the amounts of 0, 5, 10, 50 and 100mg per kg of soil. Earthworm tissues exposed to each treatment were collected on the 7th, 14th, 21st, and 28th day of the treatment. The results showed that SOD and CAT levels were significantly inhibited in the 100mgkg(-1) treatment group on day 28. MDA content in treatment groups was higher than in the control group throughout the exposure time, suggesting that DBP may lead to oxidative stress in cells. A dose-response relationship existed between DNA damage and total soil DBP levels. The comet assay showed that increasing concentrations of DBP resulted in a gradual increase in the OTM, Comet Tail Length and Tail DNA %. The degree of DNA damage was increased with increasing concentration of DBP. These results suggested that DBP induced serious oxidative damage on earthworms and induced the formation of reactive oxygen species (ROS) in earthworms. The excessive generation of ROS caused damage to vital macromolecules including lipids and DNA. DBP in the soils were responsible for the exerting genotoxic effects on earthworms.

Hyperthermia Using Antibody-Conjugated Magnetic Nanoparticles and Its Enhanced Effect with Cryptotanshinone

Heat dissipation by magnetic nanoparticles (MNPs) under an alternating magnetic field can be used to selectively treat cancer tissues. Antibodies conjugated to MNPs can enhance the therapeutic effects of hyperthermia by altering antibody-antigen interactions. Fe₃O₄ nanoparticles (primary diameter, 20–30 nm) coated with polyethylenimine (PEI) were prepared and conjugated with CH11, an anti-Fas monoclonal antibody. HeLa cell growth was then evaluated as a function of antibody and MNP/antibody complex doses. HeLa cell growth decreased with increased doses of the antibody and complexes. However, MNPs alone did not affect cell growth; thus, only the antibody affected cell growth. In hyperthermia experiments conducted using an alternating magnetic field frequency of 210 kHz, cell viability varied with the intensity of the applied alternating magnetic field, because the temperature increase of the culture medium with added complexes was dependent on magnetic field intensity. The HeLa cell death rate with added complexes was significantly greater as compared with that with MNPs alone. Cryptotanshinone, an anti-apoptotic factor blocker, was also added to cell cultures, which provided an additional anti-cancer cell effect. Thus, an anti-cancer cell effect using a combination of magnetic hyperthermia, an anti-Fas antibody and cryptotanshinone was established.

Epigallocatechin gallate effectively ameliorates fluoride-induced oxidative stress and DNA damage in the liver of rats

Environmental exposure to sodium fluoride (NaF) compounds is a worldwide health concern. Epigallocatechin gallate (EGCG) is a green tea catechin found in a variety of green tea preparations. The intention of this study was to investigate the hepatoprotective role of EGCG in NaF-intoxicated rats. Rats were orally treated with NaF alone (25 mg·(kg body mass)−1·day−1) or plus EGCG at different doses (20, 40, and 80 mg·(kg body mass)−1·day−1) for 4 weeks. Hepatotoxicity of NaF was determined by increased levels of serum hepatospecific markers and total bilirubin, along with increased levels of thiobarbituric acid reactive substances, lipid hydroperoxides, protein carbonyl content, and conjugated dienes. The hepatotoxic nature of NaF was further evidenced by the decreased activity of enzymatic and nonenzymatic antioxidant levels in liver. NaF-treated rats also showed increased DNA damage and fragmentation in hepatocytes. Administration of EGCG (40 mg·(kg body mass)−1) to NaF-intoxicated rats significantly recuperated the distorted biochemical indices, DNA damage, and pathological changes in the liver tissue. Thus, the results of the present study clearly demonstrate that EGCG has strong free radical scavenging, antioxidant, and antigenotoxic properties that protect against NaF-induced oxidative hepatic injury in rats.

Intrinsic therapeutic applications of noble metal nanoparticles: past, present and future

Biomedical nanotechnology is an evolving field having enormous potential to positively impact the health care system. Important biomedical applications of nanotechnology that may have potential clinical applications include targeted drug delivery, detection/diagnosis and imaging. Basic understanding of how nanomaterials, the building blocks of nanotechnology, interact with the cells and their biological consequences are beginning to evolve. Noble metal nanoparticles such as gold, silver and platinum are particularly interesting due to their size and shape dependent unique optoelectronic properties. These noble metal nanoparticles, particularly of gold, have elicited a lot of interest for important biomedical applications because of their ease of synthesis, characterization and surface functionalization. Furthermore, recent investigations are demonstrating another promising application of these nanomaterials as self-therapeutics. To realize the potential promise of these unique inorganic nanomaterials for future clinical translation, it is of utmost importance to understand a few critical parameters; (i) how these nanomaterials interact with the cells at the molecular level; (ii) how their biodistribution and pharmacokinetics influenced by their surface and routes of administration; (iii) mechanism of their detoxification and clearance and (iv) their therapeutic efficacy in appropriate disease model. Thus in this critical review, we will discuss the various clinical applications of gold, silver and platinum nanoparticles with relevance to above parameters. We will also mention various routes of synthesis of these noble metal nanoparticles. However, before we discuss present research, we will also look into the past. We need to understand the discoveries made before us in order to further our knowledge and technological development (318 references).

FEM numerical model study of heating in magnetic nanoparticles

Electromagnetic heating of nanoparticles is complicated by the extremely short thermal relaxation time constants and difficulty of coupling sufficient power into the particles to achieve desired temperatures. Magnetic field heating by the hysteresis loop mechanism at frequencies between about 100 and 300 kHz has proven to be an effective mechanism in magnetic nanoparticles. Experiments at 2.45 GHz show that Fe₃O₄ magnetite nanoparticle dispersions in the range of 10¹² to 10¹³ NP/mL also heat substantially at this frequency. An FEM numerical model study was undertaken to estimate the order of magnitude of volume power density, Q_gen (W m^-3) required to achieve significant heating in evenly dispersed and aggregated clusters of nanoparticles. The FEM models were computed using Comsol Multiphysics; consequently the models were confined to continuum formulations and did not include film nano-dimension heat transfer effects at the nanoparticle surface. As an example, the models indicate that for a single 36 nm diameter particle at an equivalent dispersion of 10¹³ NP/mL located within one control volume (1.0 × 10^-19 m³) of a capillary vessel a power density in the neighborhood of 10¹⁷ (W m^-3) is required to achieve a steady state particle temperature of 52 °C - the total power coupled to the particle is 2.44 μW. As a uniformly distributed particle cluster moves farther from the capillary the required power density decreases markedly. Finally, the tendency for particles in vivo to cluster together at separation distances much less than those of the uniform distribution further reduces the required power density.

Ultrasonic-activated micellar drug delivery for cancer treatment

The use of nanoparticles and ultrasound in medicine continues to evolve. Great strides have been made in the areas of producing micelles, nanoemulsions, and solid nanoparticles that can be used in drug delivery. An effective nanocarrier allows for the delivery of a high concentration of potent medications to targeted tissue while minimizing the side effect of the agent to the rest of the body. Polymeric micelles have been shown to encapsulate therapeutic agents and maintain their structural integrity at lower concentrations. Ultrasound is currently being used in drug delivery as well as diagnostics, and has many advantages that elevate its importance in drug delivery. The technique is noninvasive, thus no surgery is needed; the ultrasonic waves can be easily controlled by advanced electronic technology so that they can be focused on the desired target volume. Additionally, the physics of ultrasound are widely used and well understood; thus ultrasonic application can be tailored towards a particular drug delivery system. In this article, we review the recent progress made in research that utilizes both polymeric micelles and ultrasonic power in drug delivery.

Pathomorphologic evaluation of pulmonary radiofrequency ablation: proof of cell death is characterized by DNA fragmentation and apoptotic bodies

BACKGROUND

Radiofrequency (RF) ablation is an increasingly applied technique. Promising results of hepatic RF ablation raised expectations of its capabilities for treatment of primary and secondary lung tumors. Because of different thermal and electrical properties of lung tissue, compared with liver tissue, a simple analogy of tissue response is not possible. The authors aimed to evaluate the effectiveness of image-guided pulmonary RF ablation and to characterize pathomorphology of tissue response.

METHODS

RF ablations of 11 pulmonary malignancies in 9 patients were performed under computed tomography (CT)-guidance. Three days after RF ablation, surgical resection was performed followed by pathologic examination. Specimens were evaluated macroscopically, histologically by hematoxylin and eosin (H & E) staining, terminal deoxy-nucleotidyl transferase-mediated nick end-labeling (TUNEL), and electron microscopy.

RESULTS

Tumor tissues and adjacent lung tissues were characterized by double-strand fragmentation as determined by TUNEL. Ultrastructurally apoptotic bodies were found, indicating apoptotic cells. Criteria for tissue necrosis were not fulfilled by standard histological staining (H & E), showing preserved tissue architecture and only few microscopic cellular details suggestive of tumor regression. Because of DNA fragmentation, as determined by TUNEL and results from electron microscopy, the authors confirmed the tumor tissue to be completely ablated in 10 (90.9%) cases. However, in 2 cases, a safety margin was absent.

CONCLUSIONS

CT-guided pulmonary RF ablation of pulmonary malignancies is a locally effective treatment. Three days after RF ablation, tumor tissue seemed to be thermally fixed still showing characteristics of vital tumor tissue in standard histological staining; however the tissue proved to be in regression toward coagulative necrosis verified ultrastructurally and by TUNEL.

Genotoxic risk identification of soil contamination at a major industrialized city in northeast China by a combination of in vitro and in vivo bioassays

The present study evaluated the genotoxicity of field soils in the Tianjin area, one of the most industrialized contaminated areas in northeast China. The genotoxicity of organic extracts of 41 soils was assayed by an in vitro SOS/ umu bioassay with Salmonella typhimurium TA 1535/pSK 1002. From the 41 soil samples, 11 samples were selected to confirm the genotoxic effect by in vivo single-cell gel electrophoresis (comet assay) using earthworms (Eisenia fetida). The results obtained demonstrated that, in the in vitro assay, genotoxicity expressed as induction ratios (IR) ranged from 1.00 to 4.60, and in the in vivo assay, the genotoxicity expressed as tail moment (TM) varied from 14.6 to 57.8 microm. All samples with high genotoxicity assessed by the SOS/umu bioassay possessed significantly high genotoxic effects in the comet assay, and there was a correlation (R2 = 0.736, p < 0.05) between IR and TM in both bioassays. It is concluded that soils in the Tianjin area were seriously contaminated by organic genotoxicants and higher levels of genotoxic effects existed in soils in the urban area of Tianjin as well as in areas near the coastal towns in the northeast part of the city. It can be concluded that a combination of in vivo and in vitro bioassays as a powerful and efficient genotoxicity-assessing tool could facilitate the assessment of genotoxic risk at a regional scale.

Cell cycle dependent apoptosis and cell cycle blocks induced by hyperthermia in HL-60 cells

The effects of heat are strongly dependent on the time of heating at a given temperature. The relationship between treatment time and temperature for a biological isoeffect (the Arrhenius plot) has been confirmed for a variety of normal tissues and tumours. A marked change of slope occurs somewhere between 42-43 degrees C. Above this transition temperature the slope is constant for a variety of cells and tissues. Therefore, when defining thermal doses in hyperthermia studies, both the time and temperature of heating are equally important determinants. In this study, cell cycle progression and apoptosis were analysed in HL-60 cells after heating from 5-60 min at 45.0 degrees C and also heating with five different iso-dose time-temperature heat treatments. A heat shock of 5-15 min at 45.0 degrees C caused the accumulation of cells in G1 and G2/M phases after 12 h at 37 degrees C, whereas a heat shock of 20-60 min at 45.0 degrees C reduced the number of non-apoptotic cells in all phases because the number of apoptotic cells increased. The fraction of apoptotic cells followed a sigmoid curve as the heating time increased from 5-60 min at 45.0 degrees C. Cell cycle analysis showed that apoptosis occurred predominantly in S-phase cells for shorter heating times but in all phases at longer times. An isodose heat shock lower than 44.0 degrees C (42.0-43.0 degrees C) gave the same apoptotic index, while heat shock from 44.0-46.0 degrees C caused a greater than expected apoptotic index. Thus, there was a transition at 44.0 degrees C in HL-60 cells, above which apoptosis increased rapidly. These results indicate that isodose analysis based on clonogenic survival in fibroblast cells may not be relevant for cell types which readily undergo apoptosis. Clonogenic survival was also compared with apoptosis for HL-60 cells and an apoptotic-resistant derivative cell line, HWC-2, heated for various times at 45.0 degrees C. Survival based on a clonogenic assay was much lower than survival based only on apoptotic index at all times for HL-60 cells. HWC-2 cells did not undergo apoptosis and also had a higher clonogenic survival than HL-60 cells.

Monitoring stiffness changes in lesions after radiofrequency ablation at different temperatures and durations of ablation

The variations in the stiffness or stiffness contrast of lesions resulting from radiofrequency (RF) ablation of canine liver tissue at different temperatures and for different ablation durations at a specified temperature are analyzed. Tissue stiffness, in general, increases with temperature; however, an anomaly exists around 80 degrees C, where the stiffness of the lesion is lower than that of the lesion ablated at 70 degrees C. On the other hand, the stiffness increases monotonically with the duration of ablation. Plots illustrating the ratio of mean strains in normal canine liver tissue to mean strains in ablated thermal lesions demonstrate the variation in the stiffness contrast of the thermal lesions. The contrast-to-noise ratio (CNRe) of the lesions, which serves as an indicator of the detectability of the lesions under the different experimental imaging conditions described above, is also presented. The results presented in this paper show that the elastographic depiction of stiffer thermal lesions is better, in terms of the CNRe parameter. An important criterion in the elastographic depiction of RF-ablated regions of tissue is the trade-off between ablation temperature and duration of ablation. Tissue necrosis can occur either by ablating tissue to high temperatures for short durations or to lower temperatures for longer durations. In this paper, we attempt to characterize the elastographic depiction of thermal lesions under these different experimental conditions. This paper provides results that may be utilized by practitioners of RF ablation to decide the ablation temperature and duration, on the basis of the strain images of normal liver tissue and ablated thermal lesions discussed in this paper.

Apoptosis: a novel therapeutic tool?

Apoptosis is a genetically programmed cell death mechanism that appears to occur in all multicellular organisms. It is a normal process that serves to maintain cellular homeostasis. However, in many diseases there is a disruption in the equilibrium between cell proliferation and cell death that contributes directly to the disease. In these cases, a possible therapeutic intervention would be to restore the skewed equilibrium by pushing it in the desired direction through the use of pharmacological agents or genetic approaches. These observations have instigated substantial research in the field of apoptosis, resulting in an increasingly detailed analysis of the molecular mechanisms and the sequence of events that occur in this cell death pathway. In addition, by trying to understand this pathway, several potential therapeutic agents have arisen from those used in chemo-, radio-, and cytokine therapy. While these agents have been relatively successful, it is rare that their effect is complete. Thus, the search continues for a strategy to conquer those cells that are resistant to these regimens. Genetic approaches are novel and have been shown to be quite successful in several in vitro and animal models. They also tend to have low toxicity. It is believed that using a more traditional front-line approach of therapy, supplemented by appropriate genetic intervention, will allow substantial increases in the efficacy of treatment, while at the same time introducing little or no additional toxicity.

Synthesis and cellular uptake of porphyrin decorated iron oxide nanoparticles—a potential candidate for bimodal anticancer therapy

This paper reports the synthesis, characterization, and cellular uptake of the conjugate of porphyrin and iron oxide nanoparticles, which may lead to a bimodal anticancer agent that can be used in the combinational treatment of photodynamic therapy (PDT) and hyperthermia therapy (HT).

Whole body hyperthermia induces apoptosis in subpopulations of blood lymphocytes

Whole Body Hyperthermia (WBH) has been shown to induce alterations of lymphocyte subpopulations in peripheral blood: T-cells decrease and NK-cells increase in number in the course of this therapy. As elevated temperature induces programmed cell death in healthy lymphocytes in vitro, we intended to determine the role of lymphocyte apoptosis in WBH by measuring the rate of apoptosis in blood lymphocytes in the course of this treatment. Blood was taken from cancer patients, treated with whole body hyperthermia and chemotherapy, before, during and the day after treatment. Apoptosis rates of the whole lymphocyte population, as well as, of B-, T-, CD4 + -T-, CD8 + -T-, and Natural-Killer (NK)-cell-subpopulations were determined by staining with AnnexinV-FITC and FACS flow analysis. A significant rise of apoptosis in the whole lymphocyte population, in CD4 + -T- and in CD8 + -T-cells occurred during treatment. In contrast, an elevated rate of apoptosis in NK-cells was observed 20 hours after termination of WBH. These differences were similar when the cells were incubated at 37 degrees C for 24 hours. Our results suggest, that apoptosis is one reason for the previously described decrease of T-cells during WBH and of NK-cells after WBH, and that the hyperthermia-related apoptosis-inducing mechanism is different in T-cells and NK-cells.

Immunohistochemical detection of hepatocellular carcinoma in the setting of ongoing necrosis after radiofrequency ablation

After radiofrequency ablation (RFA), hepatocellular carcinoma undergoes complete necrosis and an ongoing necrosis that is irreversible and characterized histologically by disrupted cell outlines, homogenous cytoplasmic eosinophilia, and preserved nuclear staining, with the cells appearing quite distinct from viable cancer cells. Antibody to detect single-stranded DNA (ssDNA) specifically labeled nuclei in the setting of ongoing necrosis, but not viable tumor cells, whereas human mitochondrial antibody labeled the cytoplasm of viable cells but not cells of ongoing necrosis. The results demonstrate that RFA causes denaturation of both DNA and proteins and that the immunohistochemistry of ssDNA and mitochondrial protein is useful in detection of ongoing necrosis after RFA and provides pathological information on the validity of this procedure.

DNA damage and repair in human leukocytes exposed to styrene-7,8-oxide measured by the comet assay

Styrene-7,8-oxide (SO) is produced by cytochrome p450 monooxygenases as the main mammalian metabolite of styrene, an important industrial chemical present at high concentrations in the ambient air of fiberglass-reinforced plastic plants. Previous studies have shown positive results for SO in the induction of several cytogenetic endpoints in vitro. In this work we have evaluated, by means of the comet assay, the potential of SO to act as a DNA damaging agent in human peripheral leukocytes and the ability of white blood cells to repair the DNA damage induced by this compound. Our results show that SO induces DNA damage at concentrations higher than 50 microM in a dose-dependent manner, and that the lesions produced by SO are efficiently removed within a few hours after the end of treatment.

Apoptosis in ultrasound-produced threshold lesions in the rabbit brain

Focused ultrasound (US) surgery has been used to induce high temperature elevations in tissue to coagulate the proteins and kill the tissue. The introduction of noninvasive online temperature monitoring has made it possible to induce well-controlled thermal exposures. In this study, we used magnetic resonance imaging (MRI) thermometry to monitor thermal exposures near the threshold of tissue damage, and then investigated if apoptosis was induced. Rabbit brains were sonicated with an eight-sector phased array to create a large region of uniform temperature elevation at the end of a 30-s sonication. Histological examination demonstrated that apoptosis was induced in some cells. At 4 h after the sonications, the apoptotic cells constituted 9 +/- 7% of identifiable cells. By 48 h after the sonications, the number of apoptotic cells had increased up to 17 +/- 9%. The impact of this finding for therapy needs to be explored further.

Comet assay and DNA flow cytometry analysis of staurosporine-induced apoptosis

BACKGROUND

The ability of the comet assay to quantify DNA strand breaks and alkali labile sites has been widely demonstrated. In this study, this assay was tested for its ability to identify DNA fragmentation occurring during apoptosis in comparison with standard DNA flow cytometry analysis.

METHODS

Staurosporine-induced apoptosis in CHO cells is an adequate model to study a rapid time- and dose-dependent appearance of this process.

RESULTS

Nuclear staining with DAPI confirmed the induction of apoptosis with a typical chromatin condensation and fragmentation. Analysis of propidium-iodide- (PI) stained DNA by flow cytometry showed the presence of a pre-G1 peak, characteristic of apoptotic cells, 6 h after drug treatment. The detection of highly damaged cells (HDC) by the comet assay after 3 h treatment occurred earlier than the detection of apoptotic cells by flow cytometry. However, HDC were missed when the DNA fragmentation was too high, preventing accurate quantification of late apoptotic cells.

CONCLUSIONS

The comet assay is more sensitive than standard DNA flow cytometry to detect early DNA fragmentation events occurring during apoptosis. However, the comet assay modified by omitting electrophoresis was necessary to quantify apoptotic fraction at later stages.

[Significance of apoptotic processes in radiotherapy. II]

Apoptosis is known as an active process of cell death forced by radio- and chemotherapy. Therefore, established concepts (terms, therapy schemes) will reflect a picture different from that usually seen, when examined under the apoptotic point of view. Furthermore, the development of new concepts for innovative diagnosis, prognosis and therapy could be accomplished. This is an attempt to reveal actual features of both aspects.

Caffeine modulates heat shock induced apoptosis in the human promyelocytic leukemia cell line HL-60

The ability of caffeine to modulate hyperthermia induced apoptosis was investigated in the human promyelocytic cell line HL60. Mild hyperthermia has been shown to be a strong inducer of apoptosis in many cell lines of lymphoblastoid lineage. In this investigation HL60 cells were simultaneously exposed to caffeine (concentrations ranging from 0 to 20 mM), and a brief hyperthermic treatment (43 degrees C) for 1 h and then allowed a recovery time of 12 h. Approximately 50% of a cell population receiving the hyperthermia treatment died by apoptosis within 12 h, as determined by the comet assay, whereas cells that received concomitant treatments of caffeine with heat shock displayed an apparent suppression of apoptotic induction and enhanced cell survival.

Apoptosis: its role in the development of malignancies and its potential as a novel therapeutic target

OBJECTIVE

To review the current literature regarding the role of apoptosis in the development of malignant cells and how the induction of this pathway could be used in cancer therapy.

DATA SOURCE

A MEDLINE search of basic science articles pertinent to the understanding of the normal physiologic process of apoptosis was conducted.

STUDY SELECTION

Because of the rapidly growing literature regarding apoptosis, only articles describing key processes in the biology of the cell and the genetic control of apoptosis were included.

DATA SYNTHESIS

Apoptosis is imperative for host survival since it discards unwanted, damaged, and atypical cells. The process is therefore implicated in the continuous regulation of development, differentiation, and homeostasis. Furthermore, apoptosis is a response to physiologic and pathologic stresses that disrupt the balanced rates of cell generation and elimination. In a disease such as cancer, there is a lack of equilibrium between the rates of cell division and cell death; agents that promote or suppress apoptosis can manipulate these rates, influencing the anomalous accumulation of neoplastic cells. Pharmacologic manipulation of apoptosis can manipulate these rates, influencing the anomalous accumulation represents a novel approach in targeting malignant cells and has far-reaching implications for new directions in cancer therapy.

CONCLUSIONS

Apoptosis is a highly organized physiologic mechanism of destroying injured and abnormal cells as well as maintaining homeostasis in multicellular organisms. Both the activation and inhibition of apoptosis are tightly controlled. Pharmacologic manipulation of this pathway is a novel therapeutic target in cancer therapy.

Key morphologic changes and DNA strand breaks in human lymphoid cells: discriminating apoptosis from necrosis

Apoptosis is an important form of physiologic cell death displayed by an enormous variety of tissues under divergent conditions. The recent attention toward apoptosis in virtually all aspects of modern biology indicates that rapid and accurate differentiation between apoptosis and necrotic death is of considerable interest. Apoptosis is distinguishable from necrosis on the basis of several criteria. In this study, we undertook to examine the effects of mild hyperthermia (43 degrees C leading to apoptotic death) and severe hyperthermia (50 degrees C leading to necrotic killing) on associated DNA fragmentation. Using laser scanning and fluorescent microscopic evaluation of DNA "comets" in the single cell gel assay, we compared necrotic and apoptotic DNA damage in a variety of human leukemia and lymphoma cell lines at the level of the individual cell. We show that necrotic cells do display detectable DNA damage. We confirm our preliminary report that comet "tail moment" is sufficient to distinguish between necrotic and apoptotic DNA damage, while comet tail length may confuse the two forms. We report that a recovery period is necessary for expression of increasing apoptotic but not necrotic DNA damage. We show that apoptosis increases with prolonged hyperthermia and confirm that the mode of death changes from apoptosis to necrosis with higher heat loads, producing a greater fraction of cells showing damage. In addition, we show that for necrotic cells, DNA tail moment reflects sensitivity to prolonged exposure without a concomitant change in tail length.