effect of fasting on positron emission tomography [PET] imaging: a narrative review

As a nuclear approach, Positron Emission Tomography [PET] is a functional imaging technique which is based on the detection of gamma ray pairs emitted by a positron?emitting radionuclide. There are certain limitations to this technique such as normal tissue uptake. Therefore, it has been recommended that patients prepare before scanning. Fasting for a short while before PET imaging is an example of such preparation. In this paper, we attempted to collect the studies evaluating the effects of fasting in the three sections of cardiac, brain and abdominal PET imaging. Conclusively, we found that the effects of fasting on PET imaging can be different depending on the type of PET scanning, radiotracer, patient's diseases, fasting duration and in case of any additional dietary plans. It is proposed that further study be conducted on this subject in order to determine such effects in more detail

effect of extremely low frequency pulsed electromagnetic field on in vitro fertilization success rate in NMRI mice

The effects of exposure to electromagnetic fields [EMF] on reproduction systems have been widely debated. In this study, we aimed to investigate whether low frequency EMF could ameliorate the in vitro fertilization success rate in Naval medical research institute [NMRI] Mice. In this randomized comparative animal study, ten NMRI mice were randomly divided into 2 equal groups [control and experimental].10 IU of human chorionic gonadotropin [hCG] was injected intraperitoneally to both groups in order to stimulate ovulating, and ovums were then aspirated and kept in KSOM [modified version of sequential simplex optimization medium with a higher K+ concentration] culture medium. Metaphase II ovums were separated, and sperms obtained by "swim out" method were added to metaphase II ovums in the culture medium. The experimental group was exposed to 1.3 millitesla pulsed electromagnetic field at 4 kilohertz frequency for 5 hours. To assess the efficacy, we considered the identification of two-pronuclear zygote [2PN] under microscope as fertilizing criterion. Total number of collected ovums in the control and experimental groups was 191 and 173, respectively, from which 58 [30.05%] and 52 [30.36%] ovums were collected from metaphase II, respectively. In vitro fertilization [IVF] success rate was 77% in extremely low frequency- pulsed electromagnetic field [ELF-PEMF] for exposed group [experimental], whereas the rate was 68% for control group. Despite increased percentile of IVF success rate in exposed group, there was no statistically significant difference between 2 groups, but this hypothesis has still been stated as a question. Further studies with larger sample sizes and different EMF designs are suggested

Effects of combined sonodynamic and photodynamic therapies on a colon carcinoma tumor model

Although photodynamic therapy is considered as a noninvasive method, most photosensitizers are susceptible to ultrasound. Therefore, it is expected that the combination of two activation methods might have a synergistic effect. This probable effect has been investigated in this study. This study was conducted on colon carcinoma tumor in Balb/c mice. The tumors were induced by subcutaneous injection of CT26 cells. Ultrasound and light irradiations were performed on tumors 24 hr after injection of liposomal Zn [Il]-phthalocyanine. The treatment efficacy was evaluated using daily measurement of the tumor dimensions. Ten days post treatment, relative tumor volumes of all groups were significantly reduced in comparison with the main control group. The best response was observed when one of the two treatment methods had been applied. The longest doubling time of tumor was related to the treatment group namely photodynamic, sonodynamic and combination technique, while the shortest belonged to the control group. This study showed that liposomal Zn phthalocyanine is both photosensitizer and sonosensitizer. Photodynamic and sonodynamic therapies can be efficient in retarding tumor growth rate. In this study, the combination of two methods didn't show any improvement in therapeutic outcomes. It is predicted that latest results are related to the treatments sequence and could be optimized in the future

[Evaluation of the combined effects of sonodynamic and photodynamic therapies in a colon carcinoma tumor model[CT26]]

Photodynamic therapy is a noninvasive therapeutic method for tumors with a maximum depth 0.5 mm. On the other hand, most photosensitixers are also susceptible to ultrasound waves [the basis of sonodynamic therapy]. Therefore, it is expected that a combination of the two therapeutic methods will increase effectiveness of photodynamic therapies for lower doses of sensitizer and curing deeper tumors. This study evaluates the synergistic effects of photodynamic and sonodynamic therapies. The study was conducted on a colon carcinoma tumor model in Balb/c mice. The colon carcinoma tumors were induced in the mice by subcutaneous injection. Twenty four hours after intraperitoneal injection of Zinc Phthalocyanine liposome as a sensitixer, at first ultrasound irradiation with a known frequency and intensity was performed followed by illumination of the tumor area. Evaluation of the treatment efficacy was done using daily measurement of the tumors and calculation of their relative volumes. Also, all control groups were considered to confirm the effect of each therapeutic option in the study. In the first ten days post treatment, the relative volumes of all groups decreased significantly in comparison with the main control group, but the best response was observed in the photodynamic or sonodynamic therapy groups. The longest doubling time of tumor size was related to groups under photodynamic, sonodynamci and main therapies, and the shortest belonged to the control group. Zinc phthalocyanine lipsome is both a photosensitizer and sonsentisitizer. Photodynamic and sonodynamic therapies can be efficient in retarding tumor growth rate. In this study, combination of the two methods did not cause improved therapeutic outcomes. It is predicted that this result is related to the choice of therapeutic agents and could be optimized in future

[Evaluation of an ultrasonic insulin delivery system in hyperglycemic rabbits]

Sonophoresis has been assessed as a novel approach to crate skin permeability and drug delivery using low frequencies of ultrasound waves in the range of 20 kHz to 3 MHz. In this study, a system including seven 40 kHZ piezoelectric transducers and an insulin chamber designed by the Medical Physics Research Center has been evaluated on hyperglycemic rabbits. Thirty five rabbits became hyperglycemic through Alloxan monophydrate injection and were divided into five groups. The rabbits were treated in two main groups [with insulin and ultrasound radiation in two radiation periods], one main control group and two further control groups [one group with ultrasound radiation with longer radiation period in absence of insulin and presence of normal saline; and the other group without ultrasound radiation in presence of insulin]. By filling the system chamber with insulin and placing in on the skin of the abdomen and activating the piezoelectric transducers, blood samples were drawn from the animals before ultrasound irradiation and after it is specified intervals. The glucose level was measured using a glucometer and the serum insulin level was determined using a radioimmunoassay method. Maximum decrease in glucose level was recorded for a 20 minute irradiation in a 180 minute period, and the highest increase in insulin level was recorded for the 10 minute radiation group in a 60 minute period. Because rapid uptake and reaching a peak in a short time and its swift decrease make a good scheme for controlling glucose level after meals, the 10 minute radiation seems to be more suitable. Also, it is predicted that irradiation time in the interval between food consumption and use of the instrument is critical

Relative electropermeability and electric pulse effectiveness in human breast adenoeareinoma: an in vitro study

This study was carried out in order to evaluate the effects of electrochemotherapy, electrical pulses and chemotherapeutic drugs on the killing of cancerous cells and their probable synergistic effects. Electrochemotherapy treatments conducted on MCF-7 cell line derived from human breast adenocarcinoma tumor using four chemotherapeutic drugs including bleomycin, cisplatin, adriamycin and cyclophosphamide and six electrical doses. Cell survival assayed using MTT method, 72 hrs after the treatment; also the killing effects of each drug and electric dose determined. Finally, "Relative Pulse Effectiveness" and "Relative Electropermeability Effectiveness" calculated. All electrical doses decreased cell survival, significantly for bleomycin and cisplatin, however, they were only, significant in high concentration of cyclophosphamide and adriamycin. For the applied drugs, "Relative Electropermeability Effectiveness" was more than one [1.00], except for adriamycin. It seems that for the diffusion of molecules into cells, application of high duration electric pulses is more efficient for high molecular weight drugs while for low molecular weight drugs, strong pulses are more effective. In intermediate molecular weight, there is no difference between increasing the pulse strength and/or duration to achieve additional electropermeability. Electropermeability effect of different electric doses and electrochemotherapy efficiency can be evaluated by "REE" and "RPE", respectively