Millimeter wave dosimetry of human skin.

To identify the mechanisms of biological effects of mm waves it is important to develop accurate methods for evaluating absorption and penetration depth of mm waves in the epidermis and dermis. The main characteristics of mm wave skin dosimetry were calculated using a homogeneous unilayer model and two multilayer models of skin. These characteristics included reflection, power density (PD), penetration depth (delta), and specific absorption rate (SAR). The parameters of the models were found from fitting the models to the experimental data obtained from measurements of mm wave reflection from human skin. The forearm and palm data were used to model the skin with thin and thick stratum corneum (SC), respectively. The thin SC produced little influence on the interaction of mm waves with skin. On the contrary, the thick SC in the palm played the role of a matching layer and significantly reduced reflection. In addition, the palmar skin manifested a broad peak in reflection within the 83-277 GHz range. The viable epidermis plus dermis, containing a large amount of free water, greatly attenuated mm wave energy. Therefore, the deeper fat layer had little effect on the PD and SAR profiles. We observed the appearance of a moderate SAR peak in the therapeutic frequency range (42-62 GHz) within the skin at a depth of 0.3-0.4 mm. Millimeter waves penetrate into the human skin deep enough (delta = 0.65 mm at 42 GHz) to affect most skin structures located in the epidermis and dermis.

Effect of cyclophosphamide and 61.22 GHz millimeter waves on T-cell, B-cell, and macrophage functions.

The present study was undertaken to investigate whether millimeter waves (MMWs) at 61.22 GHz can modulate the effect of cyclophosphamide (CPA), an anti-cancer drug, on the immune functions of mice. During the exposure each mouse's nose was placed in front of the center of the antenna aperture (1.5 x 1.5 cm) of MMW generator. The device produced 61.22 +/- 0.2 GHz wave radiation. Spatial peak Specific Absorption Rate (SAR) at the skin surface and spatial peak incident power density were measured as 885 +/- 100 W/kg and 31 +/- 5 mW/cm(2), respectively. Duration of the exposure was 30 min each day for 3 consecutive days. The maximum temperature elevation at the tip of the nose, measured at the end of 30 min, was 1 degrees C. CPA injection (100 mg/kg) was given intraperitoneally on the second day of exposure to MMWs. The animals were sacrificed 2, 5, and 7 days after CPA administration. MMW exposure caused upregulation in tumor necrosis factor-alpha (TNF-alpha) production in peritoneal macrophages suppressed by CPA administration. MMWs also caused a significant increase in interferon-gamma (IFN-gamma) production by splenocytes and enhanced proliferative activity of T-cells. Conversely, no changes were observed in interleukin-10 (IL-10) level and B-cell proliferation. These results suggest that MMWs accelerate the recovery process selectively through a T-cell-mediated immune response.

Effect of millimeter waves on cyclophosphamide induced NF-kappaB.

Antiapoptotic activity of NF-Kappa B (NF-kappaB) in tumors contributes to acquisition of resistance to chemotherapy. The effect of millimeter waves (MMWs) on NF-kappaB activation induced by cyclophosphamide (CPA) was studied in the spleen of mice. CPA, an anticancer drug, caused a marked increase (58.9-fold) in NF-kappaB DNA-binding activity as compared to the control group. No significant enhancement in NF-kappaB activity (0.51-fold) was observed when the CPA group was also irradiated with MMWs. These results suggest that treatment with MMWs can inhibit activation of NF-kappaB induced by chemotherapeutic drugs.

Effect of millimeter waves on natural killer cell activation.

Millimeter wave therapy (MMWT) is being widely used for the treatment of many diseases in Russia and other East European countries. MMWT has been reported to reduce the toxic effects of chemotherapy on the immune system. The present study was undertaken to investigate whether millimeter waves (MMWs) can modulate the effect of cyclophosphamide (CPA), an anticancer drug, on natural killer (NK) cell activity. NK cells play an important role in the antitumor response. MMWs were produced with a Russian-made YAV-1 generator. The device produced modulated 42.2 +/- 0.2 GHz radiation through a 10 x 20 mm rectangular output horn. Mice, restrained in plastic tubes, were irradiated on the nasal area. Peak SAR at the skin surface and peak incident power density were measured as 622 +/- 100 W/kg and 31 +/- 5 mW/cm2, respectively. The maximum temperature elevation, measured at the end of 30 min, was 1 degrees C. The animals, restrained in plastic tubes, were irradiated on the nasal area. CPA injection (100 mg/kg) was given intraperitoneally on the second day of 3-days exposure to MMWs. All the irradiation procedures were performed in a blinded manner. NK cell activation and cytotoxicity were measured after 2, 5, and 7 days following CPA injection. Flow cytometry of NK cells showed that CPA treatment caused a marked enhancement in NK cell activation. The level of CD69 expression, which represents a functional triggering molecule on activated NK cells, was increased in the CPA group at all the time points tested as compared to untreated mice. However, the most enhancement in CD69 expression was observed on day 7. A significant increase in TNF-alpha level was also observed on day 7 following CPA administration. On the other hand, CPA caused a suppression of the cytolytic activity of NK cells. MMW irradiation of the CPA treated groups resulted in further enhancement of CD69 expression on NK cells, as well as in production of TNF-alpha. Furthermore, MMW irradiation restored CPA induced suppression of the cytolytic activity of NK cells. Our results show that MMW irradiation at 42.2 GHz can up-regulate NK cell functions.

Continuous millimeter-wave radiation has no effect on lipid peroxidation in liposomes.

The effect of millimeter waves on lipid peroxidation was studied in the presence and absence of melanin. Irradiation of liposomes with continuous millimeter electromagnetic waves at frequencies of 53.6, 61.2 and 78.2 GHz and incident power densities of 10, 1 and 500 mW/cm2, respectively, did not show an enhancement in the formation of lipid peroxides compared to unirradiated samples. Liposomes exposed to 254 nm UVC radiation at 0.32 mW/cm2 and 302 nm UVB radiation at 1.12 mW/cm2 served as positive controls. No increment in the formation of lipid peroxides was observed when irradiation of liposomes was carried out in the presence of ADP-Fe+3 and EDTA-Fe+3. Direct irradiation of melanin with millimeter waves did not exhibit an increased formation of superoxide or hydrogen peroxide. The present results indicate that millimeter waves of the above frequencies and intensities do not cause lipid peroxidation in liposomal membranes.

Skin-tumour promoting activity of methyl ethyl ketone peroxide--a potent lipid-peroxidizing agent.

The tumour-promoting activity of methyl ethyl ketone peroxide (MEKP) was tested on the skin of hairless mice using a two-stage initiation-promotion protocol. When ultraviolet radiation in the UVB region (280-320 nm) was used as tumour initiator, MEKP showed weak promoting activity. The promotional activity of MEKP was potentiated by diethyl maleate, which is known to deplete intracellular glutathione, suggesting that lipid peroxidation may be important in the tumour promotion.

The reduction of tumor initiating activity and cell mediated mutagenicity of dimethylbenz[a]anthracene by a copper coordination compound.

Cu(II) (3,5-diisopropyl salicylate)2 (CuDIPS) which is an anti-inflammatory copper coordination compound (mol. wt. 503) possessing superoxide dismutase (SOD) activity was tested to determine its effect on 7,12-dimethylbenz[a]anthracene (DMBA)-induced initiation of tumors in mouse skin and on mutagenicity to 6-thioguanine resistance in a mouse keratinocyte mediated Chinese hamster V-79 cell system. A single application of CuDIPS (0.4 mg/mouse) administered at a short interval before DMBA application when followed by 20 weeks of promotion by TPA reduced the mouse skin tumor yield by 55%. When DMBA-induced cell-mediated mutagenesis was tested in the presence of CuDIPS a significant reduction in the number of V-79 6-thioguanine resistant mutants was observed.

Effect of antioxidants on the photooxidation of fatty acids.

The effect of butylated hydroxytoluene (BHT), butylated hydroxy anisole (BHA) and tocopherol acetate on photooxidation of the fatty acids was studied. A marked increase in the photooxidation was observed in the presence of BHT, and this effect was further potentiated by hexabromobiphenyls. Conversely, BHA and tocopherol acetate as such did not show any significant effect, but greatly enhanced the photooxidation when hexabromobiphenyls were also present. Hexabromobiphenyls by themselves did not show any notable effect on the photooxidation.

Effect of tunicamycin on receptors for tumor promoters.

A progressive decline in the specific binding of [20-3H]phorbol 12,13-dibutyrate ([3H]PDBu) and glycoprotein synthesis was observed following treatment of primary mouse epidermal cells with tunicamycin, a specific inhibitor of dolichol-mediated glycosylation. Following 18 h of treatment, the specific binding of [3H]PDBu was reduced to 33-56% of the control value. The total protein synthesis determined by leucine incorporation into acid-insoluble material was not altered by this antibiotic drug. These results suggest that the receptor for phorbol diesters is, or is functionally linked to, a glycoprotein on the cell surface.

Effect of tumor promoters on lipid peroxidation in mouse skin.

Products of lipid peroxidation were measured in mouse epidermis. These were shown to increase with advancing age. Conversely, a decline in these products was observed on treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent tumor promoting agent. A decline in lipid peroxidation occurred within 4 h after application of 2 micrograms TPA and the maximum effect was seen at 22-24 h. A lesser active tumor promoter, phorbol dibenzoate; and ethyl phenylpropiolate, a purely hyperplastic agent, also lowered lipid peroxidation; while phorbol, a non-promoter, did not show any significant effect. Mezerein, a resiniferonal derivative with weak promoting activity but a potent stage II promoter, appeared to be more potent than TPA in lowering the basal levels of peroxidation. The TPA-induced decrease in lipid peroxidation could be prevented by fluocinolone acetonide, a potent antipromoting and antimitotic agent, but not by retinoic acid and tosylamino-2-phenylethylchlorimethyl-ketone which are relatively potent antipromoting agents but lack antimitotic activity, suggesting that the decrease of lipid peroxidation by tumor promoting agents is possibly related to their mitotic activity. Furthermore, skin papilloma and carcinoma contain lower levels of lipid peroxidation compared to epidermis from the same mice.

Lipid oxidation: biologic effects and antioxidants--a review.

The detection and measurement of lipid oxidation in biological systems and some biologic effects of this oxidation are reviewed. The role of lipid oxidation in the process of photocarcinogenesis and the protective effect of antioxidants against this process also are discussed. The mechanism of such protection is unknown and studies directed at elucidating the mechanism of antioxidant effect in photocarcinogenesis and in some other pathological conditons believed to involve lipid oxidation are needed. In addition to this, epoxidation of lipids observed in monolayer studies requires further investigation, particularly in the presence of some other unsaturated molecules. The possible significance of such a study--particularly in the presence of polycyclic aromatic hydrocarbon carcinogens, where formation of epoxides is generally accepted as active intermediates--is also discussed. In addition, present knowledge on the role of lipid peroxides in the destruction of proteins and biomembranes, in chemically induced toxicity and in generation of singlet oxygen is presented.

Diester waxes from skin lipids of the feet of biotin depleted and biotin supplemented turkey poults.

The neutral lipids of the skin from the feet of turkey poults fed a biotin supplemented or a biotin deficient diet consist mainly of triacyglycerols, and of mono- and diester waxes. Diester waxes from both groups were characterized as fatty acid esters of erythro-2,3-alkanediols. A comparison between fatty acid composition of the two groups, however, revealed the following significant differences. Biotin deficient birds showed a fairly high concentration of very long chain fatty acids (C36-C40) which were completely absent in biotin supplemented birds. Further, almost one-third of the fatty acids of diester waxes in biotin deficient birds were unsaturated while those from biotin supplemented birds were predominantly (96%) saturated.

Composition of novel triesters from the skin of the rhino mutant mouse.

Composition of two novel triesters, derived from the skin of the rhino mutant mouse, is described. Chemical and spectroscopic analysis of the products of pancreatic hydrolysis of the triesters showed that these are comprised predominantly of isomer I (92.7 mole %). The syntheses of two reference compounds, I-O-hexadecanoyl-2-[(14-hexadecanoyloxy)O-tetradecanoyl] 1,2-hexadecanediol (Ia) and 2-O-hexadecanoyl-1-[(14-hexadecanoyloxy)-O-tetradecanoyl]-1,2-hexadecanediol (IIa), corresponding in their structures to isomers I and II of the triester, wax have also been described.

Diesters of alkane diols and 2-hydroxy fatty acids: identification and discrimination of isomers with the aid of NMR spectroscopy.

High resolution nuclear magnetic resonance spectroscopy has been shown to be extremely useful for the identification and discrimination of naturally occurring diesters of 1,2- and 2,3-alkanediols as well as for fatty alkyl esters of acylated 2-hydroxy fatty acids. A comparison of 220 MHz spectra of 1,2 and erythro- 2,3-alkanediol diesters exhibits the following distinguishing features: (1) two non-equivalent methylene protons from the glycol group of 1,2-alkanediol diesters resonate at 3.87 ppm and 4.17 ppm respectively while these resonances are completely absent in the spectrum of 2,3-isomer; (2) methylene protons adjacent to esther carbonyl groups appear as two overlapping triplets at 2.22 ppm in 1,2-alkanediol diesters while the corresponding protons in the 2,3-isomer are displayed as two partially overlapping triplets centered at 2.15 ppm and 2.2 ppm respectively; and (3) methyl protons adjacent to glycol group in 2,3-isomer appear as downfield doublet at 1.13 ppm; this downfield doublet is not shown by 1,2-alkanediol diesters. Erythro- and threo-2,3-alkanediol diesters have also been distinguished from each other; two alpha-methylenes in erythro isomers appear as partially overlapping triplets while these protons in threo isomer display an apparent quartet centered at 2.22 ppm. Fatty alkyl esters of acylated 2-hydroxy fatty acids display a triplet at 4.79 for 2-position methylene proton, a distinguishing feature not shown by diacyl alkanediols. A distinction between diester lipids and other classes of neutral lipids has also been achieved by the study of nuclear magnetic resonance spectra, particularly in the region of 3-6 ppm.

Triester wax: a novel neutral lipid from the skin of the rhino mutant mouse.

A novel class of neutral lipids has been isolated from the skin of the rhino mutant mouse and has been characterized as a triester wax. The lipid, on saponification and transesterification, yielded fatty acids, omega-hydroxy fatty acids and 1,2-alkane diols. These products were identified by gas-liquid and thin-layer chromatography, infrared, nuclear magnetic resonance and mass spectroscopy, combined gas-liquid chromatography and mass spectrometry and chemical methods. Fatty acids were found to be predominantly of even chain length between C14 and C36 with highest concentration at C22 : 1. Hydroxy fatty acid methyl esters (trimethylsilyl ether derivatives) showed the presence of only three components in the relative abundance of 9: 70 : 21. The structure of the major component was established as 34-hydroxytetratricont-25-enoic acid and the other two components were characterized as 32-hydroxyditricont-23-enoic and 36-hydroxyhexatricont-27-enoic acids. In addition to these omega-9 unsaturates, other isomers having unsaturation at omega-7 and omega-8 were also present in small amounts. The 1,2-alkane diols were predominantly saturated in the range of C16-C24.

Neutral lipids from the skin of the rhino mutant mouse.

The neutral lipids of the skin of the Rhino mutant mouse consist mainly of fatty acid esters of sterols, fatty alcohols and 1,2-alkane diols, with strikingly low amounts of triacylglycerols. Fatty acids of wax and sterol esters were predominantly even chain monounsaturates (63 per cent) between C16 and C36 with a surprisingly high proportion of long chain lengths: the principal peaks corresponded to C32, C34, C18, C30, and C22 monoenes. The fatty alcohols showed a somewhat similar pattern, but with an even greater preponderance of long chain lengths and only small proportions shorter than C24. sterols included cholesterol, as expected, but only to the extent of about 28 per cent; the larger fraction was shown to be lathosterol (5alpha-cholest-7-en-3beta-ol). The largest single fraction (35.6 per cent) of cutaneous lipids consisted of fatty acid esters of 1.2-alkane diols. The 1,2-alkane diols were completely saturated and included odd and even chain lengths, both straight and branched, in the C16-C24 range: predominant peaks were C20, C22(iso), C16, and C22. Fatty acids of diol esters ranged between C14-C36 with major concentrations of C18, C22, C32, and C34 monounsaturates and C20 and C16 saturates.