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PubMed2006

Microwave propagation on acupuncture channels.

Quantitative studies on functional state of acupuncture points and meridians have been done mostly by electrical measurement that requires the contact of the electrode on skin and is subject to pressure, humidity, etc. In this study, a new modality of using microwave was investigated. Microwave energy in the frequency range of 250 approximately 550MHz was irradiated on an acupuncture point. Transmitted microwave energy along the meridian was measured at the next acupuncture point of the same meridian. Diabetic and cancer patients were compared with healthy persons. Normal group consisted of 50 healthy persons. Diabetic group included 50 diabetic patients. Breast cancer group had also 50 patients. All 12 meridians on both right and left hands and feet were measured. For the diabetic group, the microwave energy propagation in this frequency range was 1.417 dB lower along Lung channel and 1.601 dB higher along Spleen channel compared with the normal group regardless of sex and diabetic types. For cancer patients, the propagation was 1.620 dB lower along Liver channel and 1.245 dB higher along Kidney channel compared with the normal group. Microwave energy proved to be a potential diagnostic method.

Acupuncture Points↗
PubMed1999

Survival of Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias).

The purpose of this study was to define the relationship between survival and temperature of nematodes of the species Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias). Ten fillets (each 126 to 467 g, 0.5 to 1.75 cm thick), with an average of five larvae of Anisakis simplex per fillet, were processed to target temperatures on high (100%) power using a commercial 700-W microwave oven. Fillets were neither covered nor rotated and had a temperature probe inserted to two-thirds depth into the thickest portion. After the fillet was digested using a 1% pepsin solution, the viability of nematodes was determined by viewing them under a dissecting microscope. Survival rates were 31% at 140 degrees F (60 degrees C), 11% at 150 degrees F (65 degrees C), 2% at 160 degrees F (71 degrees C), 3% at 165 degrees F (74 degrees C), and 0% at 170 degrees F (77 degrees C). Microwave processing of standardized fillet "sandwiches," 14 cm long, 4.5 cm wide, and approximately 1.75 cm high, each of which was preinoculated with 10 live nematodes, resulted in no survival at either 160 degrees F or 170 degrees F. Using ultraviolet light to detect both viable and nonviable nematodes in fillet sandwiches as an alternative method to pepsin digestion resulted in survival rates of 1% at 140 degrees F (60 degrees C), 3% at 145 degrees F (63 degrees C), and 0% at 150 degrees F (65 degrees C). Smaller fillet sandwiches, which most likely had fewer cold spots during microwave processing, required 150 degrees F (65 degrees C), whereas larger whole fillets required 170 degrees F (77 degrees C) to kill larvae of Anisakis simplex. The parasites were most likely inactivated by a thermal mechanism of microwave treatment. Damage to the nematodes was often evident from ruptured cuticles that were no longer resistant to digestive enzymes. The high hydrostatic pressure and low chloride content of the pseudocoelomic fluid probably contributed greatly to the damage incurred by the larvae.

Animals↗
PubMed1992

[Microwave therapy for diseases of the genitourinary organs].

Microwave energy had become a valuable component in the electromagnetic spectrum. Because of its unique energy source, the microwave radiation can penetrate several centimeters into biologic tissue. The energy is absorbed and converted into heat within the tissue. Clinical applications of microwave irradiation fall into two categories; thermotherapy and hyperthermia. Microwave therapy has generated great interest in the field of urology because of its safety, efficiency, and its simplicity as a surgical tool. This review analyses the fundamentals of the science of microwave energy as a therapy and presents an in-depth discussion of its theoretical principles, unique characteristics, appropriateness of application, and its potentiality as a long-term modality for the treatment of urologically-related diseases.

Animals↗
PubMed1999

TP53 tumor suppressor protein in normal human fibroblasts does not respond to 837 MHz microwave exposure.

The TP53 tumor suppressor protein (formerly known as p53) responds to a wide variety of environmental insults. To evaluate the safety of cellular telephones, TP53 responses in human fibroblast cells were studied after exposure to 837 MHz microwaves. Cells were exposed in a temperature-controlled transverse electromagnetic (TEM) chamber to a specific absorption rate (SAR) of 0.9 or 9.0 W/kg at 837 MHz continuous-wave (CW) microwave irradiation for 2 h. The TP53 protein levels were measured by Western blot at 2, 8, 24 and 48 h after treatment. The TP53 protein levels in microwave-treated cells, sham-treated cells, and untreated cells remained unchanged relative to each other at all times tested (Fisher test and Student-Newman-Keuls test, P > 0.05). No morphological alterations were observed in microwave-treated cells compared to sham-treated cells. We conclude that TP53 protein expression levels in cultured human fibroblast cells do not change significantly during a 48-h period after exposure to 837 MHz continuous microwaves for 2 h at SAR levels of 0.9 or 9.0 W/kg.

Cells, Cultured↗
PubMedDate not supplied

Use of microwave digestion and atomic absorption spectrophotometry to determine chromic oxide as a digestibility marker in feed, feces, and ileal content.

Most conventional digestion procedures, such as dry ashing and wet ashing, are tedious and labor intensive. Microwave digestion is a good alternative, because microwave dissolution is faster, safer, and simpler, and provides more controlled reproducible conditions than conventional methods. The purpose of this study was to develop a microwave digestion method for mineralizing meat and bone meal diets, feces, and ileal contents. Each sample was heated on a hot plate for 10 min, dry ashed at 65 degrees C for 4 h, and transferred into microwave vessels. Then, 10 mL 70% HNO3 was added. Samples were digested for 7, 10, and 20 min at 95, 90, and 85% power, respectively. After the heating cycle, 6 mL 30% H2O2 was added, and samples were returned to the microwave for a second heating cycle of 1 and 7 min at 95% and 90% power, respectively. Finally, chromium concentration was determined by flame atomic absorption spectrophotometry. The digestion method was validated by using a standard reference material, SRM domestic sludge 2781, with a certified chromium value of 195 +/- 9 micrograms/g. The value obtained in this study was 178 +/- 11 micrograms/g, for a difference of 17 micrograms/g. Spike recovery experiments resulted in 103.16 and 100.35% recoveries of chromium from diet and feces samples, respectively. Coefficients of variation were 10.8 and 7.8%, respectively.

Animal Feed↗
PubMed1999

[Indication of percutaneous microwave coagulation therapy for hepatocellular carcinoma].

Multifocal carcinogenesis is caused by a persistent infection of hepatitis viruses, and is considered to be the main cause of post-operational recurrences of hepatocellular carcinoma. It has been generally believed that a single therapeutic modality (including resection therapy) cannot improve the survival rate. In this paper, we describe the efficacy of microwave coagulation therapy and its indications based on an analysis of cases experienced at our institution over a 10-year period. We compared the background factors, recurrence rate, and survival rate of various therapies, and concluded that microwave coagulation therapy is highly effective for tumor coagulation and necrosis. Microwave coagulation therapy is also technically easier than a surgical operation, has fewer complications, and results in an equally good survival rate when compared to hepatectomy. Due to these intrinsic advantages, microwave therapy is useful not only as a treatment after recurrence, but also as a primary therapy of small liver tumors. When the detection rate for small liver tumors increases, microwave coagulation therapy will start to play an even more important role in the treatment strategy for hepatocellular carcinomas as a less invasive option, in addition to laparotomic and percutaneous/laparoscopic surgeries.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Validation of a microwave sterilizer for injection ampules.

A program for validating the microwave sterilizer, which is a new type of sterilizer, was established and implemented. This program includes the following tests specific to microwave sterilizers: the internal pressure strength of ampules, the acceptable range of sterilizing temperature, performance and calibration of the infrared thermometer and the plane blackbody, maintaining of sterilizing temperature, the processing speed (sterilizing time), the unacceptable ampules selection mechanism, microwave leaks, and a microbiological challenge test of the ampule head space using a biological indicator. Injectable preparations of mecobalamin and diprophylline were used as models for validation of the microwave sterilizer. The bioburden approach was used for injectable mecobalamin preparation, and the over-kill approach was used for injectable diprophylline preparation. The basis for practical use of this microwave sterilizer has been confirmed by the establishment and implementation of this validation program.

Drug Packaging↗
PubMed2001

[Effect of vitamin E on morphological variation of retinal ganglion cells after microwave radiation].

To determine the morphological variation in the primary cultured pig retinal ganglion cells induced by microwave and the protection of VE can supply some experiment foundation for study of effect of microwave and its protection. Retinal ganglion cells of pig were cultured in vitro and added VE of different concentration, Each group was taken after 30 mW/cm2 microwave intensity radiated for 1 h in shielded room by 2450 MHz continuous wave physiotherapy machine. Immediately after radiation, the morphological variation of cells was observed by optics microscope and transmission electronic microscope. The result showed that a portion of cells congregated, with their axon disappeared after radiation. Mitochondria and endoplasmic reticulum are detected swelling by transmission electronic microscope. The results showed that A poptosis cells can be observed. Cells of VE added groups had not obvious changes with optics microscope, but could be found that mitochondria swelling lightly and integrate mitochondria cristae by transmission electronic microscope. The results showed that microwave induced the morphological damage in primary cultured retinal ganglion cells, VE could reduced the damage of retina ganglion cells by microwave in some extent.

Animals↗
PubMed2000

Microwave technique in histopathology and its comparison with the conventional technique.

125 formalin fixed human tissues from different organs and 50 fresh animal tissues were taken. Each tissue piece was divided into two. Fresh animal tissues were fixed and processed in a domestic microwave oven and formalin fixed tissue were only processed in microwave oven. Simultaneous conventional processing was also carried out. Among the fresh tissues, 34 pieces were fixed in 10% formalin and 16 were stabilized in normal saline, with microwave irradiation. For histoprocessing graded ethanol (70% and absolute) for 150 tissues and graded isopropanol (70% and absolute) for 25 tissues were used for dehydration in microwave technique. Chloroform for 95 tissues, xylene for 15 tissues and isopropanol for 65 tissues were used as clearing agent in microwave technique. Liquid paraffin was impregnating agent in all 175 cases. The oven was operated at 50% power for 10 cases and 40% power for 165 cases. Recording of temperature could not be done. Regarding fixation with formalin 80% cases gave satisfactory result, while with normal saline, only 30% cases were satisfactory. Regarding dehydration with ethanol 80% were satisfactory and with isopropanol 60% were satisfactory. Regarding clearing--both chloroform and isopropyl alcohol gave satisfactory results in 80% cases but with, xylene tissues were fragmented and brittle.

Animals↗
PubMed2001

[Tumor ablation with MRI navigation--a novel method of microwave coagulation therapy for hepatic tumor].

Fifty-eight patients with hepatic tumor which consisted of 22 hepatocellular carcinomas and 36 metastatic liver tumors were treated by microwave coagulation therapy with MRI navigation. The tumors were located in all segments of liver except S1. In 24 cases among them, the abdominal approach was difficult, because the tumors were located just below the diaphragm. These cases were selected for thoracoscope-assisted microwave ablation under MR-guidance across the diaphragm. All MR data were collected on a vertically oriented open MRI system (0.5 T SIGNA SP/i system: GE Medical Systems). The microwave electrode was introduced into the liver through a 14G needle via a percutaneous puncture with real-time MR image navigation. Microwave ablations at 60 W for 60 seconds were repeated several times depending on the tumor size. MR imaging may be employed as a reliable guide for percutaneous puncture. Moreover, sufficient safety margin could be obtained for hepatic tumor ablation. MR-guided microwave thermoablation therapy is a feasible method of treatment for hepatic tumors.

Carcinoma, Hepatocellular↗
PubMed1999

[Transurethral microwave tissue coagulation therapy for carcinoma of urinary bladder: an analysis of 35 patients].

OBJECTIVE: To study the reliability of transurethral microwave tissue coagulation therapy for transitional epithelial carcinoma of the urinary bladder. METHODS: The suitable microwave output was affirmed by studying its coagulation effect on pig and human bladder wall according to histo-morphologic changes: Based on this study, transurethral microwave tissue coagulation of bladder cancer (TUMTCBC) was carried out in 35 patients with bladder carcinoma. Biopies were taken from the microwave irradiated sites after the procedure. All patients were given regular intravesical chemotherapy with mitomycin C after microwave treatment and were followed-up for a mean of 56 months. RESULTS: The treatment was effective in all of the treated patints. The recurrence rate and the tumor-free period in patients treated with TUMTCBC was comparable to those in patients treated with transurethral electric cauterization or partial cystectomy. In 19 cases (54.3%), no recurrence of tumor was found in 5 years. CONCLUSION: TUMTCBC is safe, effective and easy to perform. It may be used for the treatment of both superficial and invasive bladder carcinoma.

Adult↗
PubMed2002

[The microarray study on the stress gene transcription profile in human retina pigment epithelial cells exposed to microwave radiation].

OBJECTIVE: To study the difference in stress and apoptosis related genes transcription between hTERT-RPE1 cells exposed to simulated microwave radiation and the cells with heat water bath, and the effects of microwave on gene transcription in cultured human retina pigment epithelial cells. METHODS: cDNA microarray technique was used to detect the mRNA isolated from hTERT-RPE1 cells exposed to 2 450 MHz simulated microwave radiation and with heat water bath, respectively. RESULTS: Among the 97 related aim genes, there were seven genes up-regulating its transcription, i.e., M31166 (2.52fold), L24123 (2.66fold), AF039704 (2.22fold), U67156 (2.07fold), AF040958 (2.13fold), NM-001423 (2.63fold) and NM-005346 (3.68fold). But, no notably down-regulating gene in transcription was detected. CONCLUSIONS: Microwave could induce up-regulating in multiple stress and apoptosis related genes transcription in cultured human retina pigment epithelial cells, hTERT-RPE1 cells. Microwave radiation has unique effect itself in addition to its heat effect.

Gene Expression Profiling↗
PubMed2003

[Application of microwave coagulation in treatment of cancer of oral cavity: summary of 96 cases].

BACKGROUND & OBJECTIVE: There was few report about the protection of oral function of microwave coagulation in treatment of cancer of floor of the mouth. This study was designed to systematically clarify the principle, operation, treatment of the primary cancer and lymph nodes, efficiency, function of the mouth, complications and indications of the microwave coagulation in treatment of the cancer of the oral cavity. Based on this, the significance of the two special methods and prevention of bleeding during the cause were discussed. METHODS: Ninety-six cases with cancer of oral cavity who were treated with microwave coagulation were analyzed retrospectively. The survival rates and the recurrent rates of those with the coagulated tissue be resected or unresected, and of the positive margin group and the negative margin group were compared for analyzing the complications and prevention of them. RESULTS: The difference of the survival rates of those whose coagulated tissue pathologically positive and negative was insignificant (Log Rank = 0.70, P = 0.4033), and the differences of the recurrent rates of the primary site, secondary site and the uncertain site of them were also insignificant (chi 2 = 1.65, 0.837, 0.003; P = 0.684, 0.36, 0.959). The overall survival rate of the patients with negative margin was better than those of with positive margin (Log Rank = 6.08, P = 0.0136). However, the difference of the recurrent rates of them was insignificant (chi 2 = 0.327, P = 0.567). The total complication rate of 96 patients was 9.6% and all of them were acceptable. The complication rate of those with the coagulated tissue be resected was lower than that of the unresected (P = 0.013). CONCLUSION: Ligating the tongue artery, resecting the coagulated tissue, and packing the wound margin were effective methods to prevent the bleeding. The pathological result of the coagulated tissue could not be used to predict the prognosis. It is best to hold enough treatment range for microwave coagulation. Application of microwave coagulation in treatment of cancer of oral cavity has the advantage of less and slight complications.

Adult↗
PubMed2002

Changes in gap junctional intercellular communication in rabbits lens epithelial cells induced by low power density microwave radiation.

OBJECTIVE: To demonstrate the changes in gap junctional intercellular communication (GJIC) mediated by low power density microwave radiation in rabbits lens epithelial cells (LECs) and its mechanisms. METHODS: Rabbits' eyes were exposed to 5 mW/cm(2) and 10 mW/cm(2) power densities of microwave radiation for 3 hours. The fluorescence-recovery-after-photobleaching (FRAP) method was used to determine the GJIC. The localization and function of connexin 43 in LECs was detected by laser scanning confocal microscopy. RESULTS: The GJIC of rabbits LECs was inhibited by microwave radiation especially in the 10 mW/cm(2) irradiated samples. A decrease in connexin 43-positive staining was seen in 5 mW/cm(2) x 3 h treated LECs. Intracellular space accumulation and cytoplasmic internalization were clearly demonstrated in 10 mW/cm(2) group. CONCLUSIONS: Low power densities microwave radiation (5 mW/cm(2) and 10 mW/cm(2)) induces damage to connexin 43 and inhibits the GJIC of rabbits LECs. These changes result in an osmotic imbalance within the lens and induce early cataract. 5 mW/cm(2) or 10 mW/cm(2) microwave radiation is cataractogenic.

Animals↗
PubMed2000

[Zinc protective effects on pig retinal pigment epithelial cell damage of lipid peroxide induced by 2450 MHz microwave].

To observe the lipid peroxide damage in the cultured pig retinal pigment epithelial cell(RPE) induced by microwave and the protective effects by zinc (Zn). RPE cells were divided into 3 groups in terms of microwave intensity(the group of 10, 20 and 30 mW.cm-2) and each group was exposed to microwave for 1 hour. After adding ZnSO4 into DMEM culture fluid, the group of 30 mW.cm-2 was exposed to microwave. The activity of SOD and the content of MDA were measured. The results showed that the activity of SOD decreased significantly compared with the control group(P < 0.001). The content of MDA increased significantly compared with the control group(P < 0.001). Administration of Zn alleviated the increase of MDA and decrease of SOD. In the experiment, 2450 MHz microwave induces the lipid peroxide damage in RPE cells. Zn can enhance the antioxidation ability of cells and alleviate the damage to some extent.

Animals↗
PubMed2003

[Effects of microwave irradiation on ATPase activity and voltage dependent ion channel of rat hippocampus cell membrane].

OBJECTIVE: To study the effect of microwave irradiation on hippocampus cell. METHOD: Changes of ATPase activity and voltage dependent ion channel of hippocampus cell membrane were observed in mice exposed to 2 450 MHz microwave irradiation of 10 mW/cm2 from a physical therapy machine. Histochemical method and patch clamp method were used to determine the activity of Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase and voltage dependent Na+, K+, Ca2+ channels respectively. RESULT: 1) Na+, K(+)-ATPase activity of microwave irradiated mice showed no significant change as compared with the control, but the activity of Ca2+, Mg(2+)-ATPase decreased significantly (P< 0.05); 2) In microwave irradiated mice, Na+, K+, Ca2+, current inducement rate in hippocampus neuron decreased significantly, the membrane voltage of Na+ current peak shifted to depolarization, and the attenuation rate of Na+ current and current A inducement rate decreased significantly as compared with control mice. CONCLUSION: Irradiation of 2 450 MHz microwave at a doze of 10 mW/cm2 was not fatal to mice hippocampus cell. But Ca2+, Mg(2+)-ATPase activity of hippocampal cell membrane and voltage dependent Na+, K+, Ca2+ ion channel of hippocampal nervous were affected which would affect study and memory.

Animals↗
PubMed2003

A randomised trial comparing local versus general anaesthesia for microwave endometrial ablation.

OBJECTIVE: To compare the acceptability of microwave endometrial ablation using a local anaesthesia/sedation regime or general anaesthesia. To compare recovery following treatment with each type of anaesthetic. DESIGN: Prospective randomised controlled trial with follow up of women who declined randomisation. SETTING: The gynaecology department of a large teaching hospital in the UK. POPULATION: All women referred for microwave endometrial ablation at the Aberdeen Royal Infirmary between July 1999 and September 2000 without a medical reason to favour one or other type of anaesthetic. METHODS: 191 women were equally randomised to undergo microwave endometrial ablation under general or local anaesthesia. Details were also collected for women not randomised because of an anaesthetic preference. All procedures were undertaken in an operating theatre. MAIN OUTCOME MEASURES: Data collected by questionnaire including the woman's view of treatment acceptability, operative details and post-operative recovery. RESULTS: Sixty-nine percent of eligible women would consider treatment under local anaesthesia. Ninety-one percent of microwave endometrial ablation procedures that started under local anaesthesia were completed without conversion to general anaesthesia. Anaesthetic type and allocation by randomisation or preference made no significant difference to the proportion of women describing treatment as totally or generally acceptable at two weeks. Neither parity nor cavity size predicted acceptability. Women allocated general anaesthesia were more likely to describe the procedure as totally acceptable and to choose the same anaesthetic again. There was no significant difference between anaesthetic groups regarding post-operative pain, nausea or recovery time. CONCLUSIONS: Microwave endometrial ablation under local anaesthesia was acceptable to the majority of women referred for treatment. There was no recovery advantage from local anaesthesia and almost 1 in 10 women who starting treatment under local anaesthesia needed a general anaesthetic because of discomfort. The incidence of post-operative pain and nausea means that treatment with this local anaesthetic/sedation regime remains a day case rather than an outpatient procedure.

Adult↗
PubMed2003

[Benefit of microwaves in case of heat-sensitive agglomerate drying].

The microwave assisted vacuum drying of heat-sensitive materials is increasing in the pharmaceutical industry since the eighties. This paper deals with results of two experiment series obtained on a laboratory scale single pot dryer (Collette Ultima 251). Firstly water was heated up to the boiling point exclusively by predetermined microwave energy and then by various wall temperatures in order to determine the convection efficiency of the system. The experiments were carried out at fixed pressure level (80 mbar) and with optimum bowl load (15 kg). According to the demonstrated idea each single pot system efficiency can be specified at any type and quantity of load. With the help of the presented results the second experiments were designed to compare the microwave and convection efficiency of the single pot system during granule drying. A placebo granule was dried either by an exclusive convection or microwave method up to the determined LOD (< 0.5%). According to the tests extreme high wall temperature (85 degrees C) had to be used to achieve the same drying time--and efficiency--as with the usage of dielectric heating. Based on the results it can be stated that the shorter drying time under favourable conditions is the advantage of microwave radiation over the conventional technique.

Drug Industry↗