Heat-induced apoptosis in human prostatic stromal cells

Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy

Purpose

To summarize current knowledge on intracorporeal laser lithotripsy in flexible ureterorenoscopy (fURS), regarding basics of laser lithotripsy, technical aspects, stone clearance, lithotripsy strategies, laser technologies, endoscopes, and safety.

Methods

A scoping review approach was applied to search literature in PubMed, EMBASE, and Web of Science. Consensus was reached through discussions at the Consultation on Kidney Stones held in September 2019 in Copenhagen, Denmark.

Results and conclusions

Lasers are widely used for lithotripsy during fURS. The Holmium laser is still the predominant technology, and specific settings for dusting and fragmenting have evolved, which has expanded the role of fURS in stone management. Pulse modulation can increase stone ablation efficacy, possibly by minimizing stone retropulsion. Thulium fibre laser was recently introduced, and this technology may improve laser lithotripsy efficiency. Small fibres give better irrigation, accessibility, and efficiency. To achieve optimal results, laser settings should be adjusted for the individual stone. There is no consensus whether the fragmentation and basketing strategy is preferable to the dusting strategy for increasing stone-free rate. On the contrary, different stone scenarios call for different lithotripsy approaches. Furthermore, for large stone burdens, all laser settings and lithotripsy strategies must be applied to achieve optimal results. Technology for removing dust from the kidney should be in focus in future research and development. Safety concerns about fURS laser lithotripsy include high intrarenal pressures and temperatures, and measures to reduce both those aspects must be taken to avoid complications. Technology to control these parameters should be targeted in further studies.

Enhancement of Apoptosis by Titanium Alloy Internal Fixations during Microwave Treatments for Fractures: An Animal Study

Objective

Microwaves are used in one method of physical therapy and can increase muscle tissue temperature which is useful for improving muscle, tendon and bone injuries. In the study, we sought to determine whether titanium alloy internal fixations influence apoptosis in tissues subjected to microwave treatments at 2,450 MHz and 40 W during the healing of fractures because this issue is not yet fully understood.

Methods

In this study, titanium alloy internal fixations were used to treat 3.0-mm transverse osteotomies in the middle of New Zealand rabbits’ femurs. After the operation, 30-day microwave treatments were applied to the 3.0 mm transverse osteotomies 3 days after the operation. The changes in the temperatures of the muscle tissues in front of the implants or the 3.0 mm transverse osteotomies were measured during the microwave treatments. To characterize the effects of titanium alloy internal fixations on apoptosis in the muscles after microwave treatment, we performed TUNEL assays, fluorescent real-time (quantitative) PCR, western blotting analyses, reactive oxygen species (ROS) detection and transmission electron microscopy examinations.

Results

The temperatures were markedly increased in the animals with the titanium alloy implants. Apoptosis in the muscle cells of the implanted group was significantly more extensive than that in the non-implanted control group at different time points. Transmission electron microscopy examinations of the skeletal muscles of the implanted groups revealed muscular mitochondrial swelling, vacuolization. ROS, Bax and Hsp70 were up-regulated, and Bcl-2 was down-regulated in the implanted group.

Conclusion

Our results suggest that titanium alloy internal fixations caused greater muscular tissue cell apoptosis following 2,450 MHz, 40 W microwave treatments in this rabbit femur fracture models.

Acute and long-term effects of hyperthermia in B16-F10 melanoma cells

OBJECTIVE

Hyperthermia uses exogenous heat induction as a cancer therapy. This work addresses the acute and long-term effects of hyperthermia in the highly metastatic melanoma cell line B16-F10.

MATERIALS AND METHODS

Melanoma cells were submitted to one heat treatment, 45°C for 30 min, and thereafter were kept at 37°C for an additional period of 14 days. Cultures maintained at 37°C were used as control. Cultures were assessed for the heat shock reaction.

RESULTS

Immediately after the heat shock, cells began a process of fast degradation, and, in the first 24 h, cultures showed decreased viability, alterations in cell morphology and F-actin cytoskeleton organization, significant reduction in the number of adherent cells, most of them in a process of late apoptosis, and an altered gene expression profile. A follow-up of two weeks after heat exposure showed that viability and number of adherent cells remained very low, with a high percentage of early apoptotic cells. Still, heat-treated cultures maintained a low but relatively constant population of cells in S and G(2)/M phases for a long period after heat exposure, evidencing the presence of metabolically active cells.

CONCLUSION

The melanoma cell line B16-F10 is susceptible to one hyperthermia treatment at 45°C, with significant induced acute and long-term effects. However, a low but apparently stable percentage of metabolically active cells survived long after heat exposure.

Transurethral microwave thermotherapy for the treatment of BPH: still a challenger?

Minimally invasive therapies for treatment of benign prostatic hyperplasia (BPH) compete with the gold standard transurethral resection of the prostate (TURP). Comparisons of efficacy and safety have broadened the knowledge of different treatment modalities. Concerns of quality of life such as unaltered sexual function as well as cost considerations drive the market to develop techniques of lower level invasiveness. Among the competitors the office based transurethral microwave thermotherapy (TUMT) provides the broadest scale of scientific data. Numerous manufacturers sell various modifications of this technology. According to different clinical studies TUMT proved to be an effective, safe, and durable therapy for the treatment of lower urinary tract symptoms (LUTS) secondary to BPH. However, TURP still holds the steadier long-term results and is more effective to reduce obstruction as well as other LUTS.

Overexpression of manganese superoxide dismutase promotes the survival of prostate cancer cells exposed to hyperthermia

It has been hypothesized that exposure of cells to hyperthermia results in an increased flux of reactive oxygen species (ROS), primarily superoxide anion radicals, and that increasing antioxidant enzyme levels will result in protection of cells from the toxicity of these ROS. In this study, the prostate cancer cell line, PC-3, and its manganese superoxide dismutase (MnSOD)-overexpressing clones were subjected to hyperthermia (43 degrees C, 1 h). Increased expression of MnSOD increased the mitochondrial membrane potential (MMP). Hyperthermic exposure of PC-3 cells resulted in increased ROS production, as determined by aconitase inactivation, lipid peroxidation, and H2O2 formation with a reduction in cell survival. In contrast, PC-3 cells overexpressing MnSOD had less ROS production, less lipid peroxidation, and greater cell survival compared to PC-3 Wt cells. Since MnSOD removes superoxide, these results suggest that superoxide free radical or its reaction products are responsible for part of the cytotoxicity associated with hyperthermia and that MnSOD can reduce cellular injury and thereby enhance heat tolerance.

Application of External Microwave Thermotherapy in Urology: Past, Present, and Future

The excellent clinical results of transurethral microwave thermotherapy (TUMT) for the treatment of symptomatic benign prostatic hyperplasia (BPH) gave to TUMT the leading position among the microwave thermotherapy modalities available for the treatment of different urologic conditions. Research in TUMT has focused on operating software, temperature monitoring, intraprostatic heat distribution, cell-kill calculations, and correlations with clinical variables. Randomized comparisons of TUMT with other established therapies for BPH, including transurethral resection, have facilitated the evaluation of the clinical outcome, durability, morbidity, and costs of the treatment. The applications of microwave thermotherapy in other urologic diseases are also presented in this review.

Transurethral microwave thermotherapy for benign prostatic hyperplasia

Transurethral resection of the prostate (TURP) remains the gold standard for treatment of benign prostatic hyperplasia (BPH). In general, while this procedure is safe, patients require a spinal, epidural, or general anesthesia and often several days of hospital stay; the potential morbidity and mortality limits the use of TURP in high-risk patients. Pharmacotherapy has been recommended as a first-line therapy for all patients with mild to moderate symptoms. Patients are often times enthusiastic if they are offered a one-time method to treat lower urinary tract symptoms secondary to BPH, provided that the method offers reduced risk and allows an efficacy equal to that of medical therapy. One such method is transurethral microwave thermotherapy (TUMT). TUMT involves the insertion of a specially designed urinary catheter with a microwave antenna, which heats the prostate and destroys hyperplastic prostate tissue. TUMT allows the avoidance of general or regional anesthesia, and results in minimal blood loss and fluid absorption. In this review, the authors discussed the current indications and outcome of TUMT, including the history of the procedure, the mechanism of action, the indications for TUMT, the pre-operative considerations, the patient selection, the results in terms of efficacy, by comparing TUMT vs. Sham, TUMT vs. Alpha-blocker and TUMT vs. TURP. Finally, the complications are presented, as well as other uses and future directions of the procedure. The authors concluded that TUMT is a safe and effective minimally invasive alternative to treatment of symptomatic BPH.

Hyperthermia at 43 degrees C for 2h inhibits the proliferation of vascular smooth muscle cells, but not endothelial cells

Restenosis after angioplasty is one of the most critical problems of the various interventional therapies for myocardial ischemia. It has been difficult to prevent the vascular smooth muscle cells (VSMCs) proliferation resulting in restenosis. The goal of this study was to prove the treatment by hyperthermia to be effective in suppressing VSMC's proliferation in vitro. When just-stimulated VSMCs, which were incubated for 2h after 5% FBS stimulation to quiescent VSMCs, were exposed to hyperthermia (43 degrees C, 2h), the cell cycle progression to S and G2/M phase was significantly delayed 24h after 5% FBS stimulation. And another 24h later, cell death was observed partly (19%) of heat-treated VSMCs. Nonetheless, hyperthermia under the same conditions did not result in the death of quiescent VSMCs, and did not inhibit the proliferation of cultured bovine aortic endothelial cells (BAECs). In addition, we found that hyperthermia (43 degrees C, 2h) elevated p27(Kip1) over the amount induced in confluent VSMCs. Much elevation of p27(Kip1), which is a negative regulator of G1/S progression, may play a role in heat-induced G1 arrest of VSMCs. In conclusion, we have found that hyperthermia (43 degrees C, 2h) inhibited the proliferation of the dividing VSMCs mainly due to G1 arrest with neither inhibiting the generation of BAECs nor damaging quiescent VSMCs. Hence, our data suggest that hyperthermia may be clinically applicable for the prevention of restenosis.

Morphological and biological predictors for treatment outcome of transurethral microwave thermotherapy

The proliferation of prostatic tissue as a result of ageing typically leads to prostatic enlargement, which often causes obstruction of urine outflow from the bladder, clinically lower urinary tract symptoms, detrusor instability, incomplete bladder emptying, urinary infection, and finally acute urinary retention. The first approach to therapy depending on the severity of the symptoms is usually medical management (phytotherapy, alpha-blockers, 5 alpha-reductase inhibitors) before surgical procedures are performed. The reference standard for treatment of benign prostatic hyperplasia is transurethral resection of the prostate, although the introduction of minimally invasive alternatives such as transurethral microwave thermotherapy has led to a new era in surgical management. Suitable patients must be selected carefully on the basis of individual parameters that predict a favourable result.

Minimally invasive procedures as an alternative to medical management for lower urinary tract symptoms of benign prostatic hyperplasia

Data are reviewed relating to the safety and efficacy of minimally invasive transurethral microwave thermotherapy and medical management in patients with lower urinary tract symptoms of benign prostatic hyperplasia. Recent evidence is summarized indicating more pronounced long-term beneficial effects of microwave treatment. alpha-Blockade, however, offers the advantage of more rapid action than microwave treatment. Neoadjuvant and adjuvant alpha-blocker therapy can accelerate symptom and flow rate improvement in patients receiving microwave treatment. Compared with medical management, microwave treatment possesses greater versatility, allowing patients with severe baseline symptoms and small prostate sizes to be treated with a high probability of success.

Heat treatment of the prostate: where do we stand in 2000?

Various minimally invasive modalities that are aimed at alleviating lower urinary tract symptoms employ heat-induced ablation of hyperplastic prostatic tissue. Following extensive studies, most of these modalities were eventually abandoned. High-energy transurethral microwave thermotherapy has survived, however, and has gained a firm position as a therapeutic modality, along with transurethral resection of the prostate. Recent research addressed fundamental issues of mode of action of microwave treatment, and revealed the overall efficacy of this treatment, determined new indications, and rendered high-energy transurethral microwave thermotherapy more acceptable to the patients. Insights into intraprostatic vascularization and treatment monitoring were also gained as a result of these global research efforts.

Cell-kill modeling of microwave thermotherapy for treatment of benign prostatic hyperplasia

PURPOSE

We investigated whether cell-kill modelling could be used as a mean for predicting the outcome of microwave thermotherapy for benign prostate hyperplasia (BPH).

METHODS

The two models--Henriques' damage integral and Jung's compartment model--were implemented in a computer program. Real treatment data for 22 patients with BPH who were in chronic retention were used as input, including measured intraprostatic temperatures and microwave power. To test if modelling gives results that are consistent with actual observations, comparison with transrectal ultrasound (TRUS) measurements of the prostate volume before and after treatment was made. The sensitivity of the computer model for variations in the heat cytotoxicity and the temperature probe location in the adenoma was also tested.

RESULTS

The average TRUS volume reduction 3 months after treatment was 26 cc, whereas the corresponding cell kill calculation was 27 cc. The computer model appears to be rather insensitive to minor uncertainties in heat sensitivity and location of the intraprostatic reference temperature sensors.

CONCLUSION

Cell-kill modelling appears to give results that are consistent with actual observations. The coagulated tissue volume is calculated in real time during the treatment, thereby providing an immediate prediction of the treatment outcome. By using cell-kill modelling, the endpoint of a treatment can be set individually; e.g., when a certain volume reduction has been achieved.