5-Thio-D-glucose selectively potentiates hyperthermic killing of hypoxic tumor cells

Stereoselective synthesis of (+)-5-thiosucrose and (+)-5-thioisosucrose

(+)-5-Thiosucrose 1, a novel isosteric sulfur analog of sucrose, was synthesized stereoselectively for the first time via indirect β-d-fructofuranosidation involving selective β-d-psicofuranosidation, followed by stereo-inversion of the secondary hydroxy group at the C-3 position on the furanose ring. Glycosidation of protected 5-thio-d-glucose with a d-psicofuranosyl donor provided β-d-psicofuranosyl 5-thio-α-d-glucopyranoside and that with d-fructofuranosyl donor gave α-d-fructofuranosyl 5-thio-α-d-glucopyranoside. Two anomeric stereocenters of the glycosyl donor and acceptor were controlled correctly to provide a single disaccharide among four possible anomeric isomers in the glycosylation. Conversion of the resulting disaccharides afforded (+)-5-thiosucrose 1 and (+)-5-thioisosucrose 2 in excellent yields, respectively. Inhibitory activities of 1 and 2 against α-glucosidase in vitro were also examined.

(+)-5-Thiosucrose and (+)-5-thioisosucrose were stereoselectively synthesized among four possible anomeric isomers using 5-thio-d-glucose as an α-directing glycosyl acceptor.

Synthesis of 2-Thiocarbohydrates and Their Binding to Concanavalin A

A convenient and general synthesis of 2-thiocarbohydrates via cerium ammonium nitrate oxidation of the thiocyanate ion is described. Radical addition to glycals proceeds with excellent regio- and good stereoselectivities in only one step, deprotection affords water-soluble 2-thio saccharides. Binding studies to Con A have been performed by isothermal titration calorimetry (ITC) and saturation transfer difference (STD) NMR spectroscopy. The 2-thiomannose derivative binds even stronger to Con A than the natural substrate, offering opportunities for new lectin or enzyme inhibitors.

Rationale of hyperthermia for radio(chemo)therapy and immune responses in patients with bladder cancer: Biological concepts, clinical data, interdisciplinary treatment decisions and biological tumour imaging

Bladder cancer, the most common tumour of the urinary tract, ranks fifth among all tumour entities. While local treatment or intravesical instillation of bacillus Calmette-Guerin (BCG) provides a treatment option for non-muscle invasive bladder cancer of low grade, surgery or radio(chemo)therapy (RT) are frequently applied in high grade tumours. It remains a matter of debate whether surgery or RT is superior with respect to clinical outcome and quality of life. Surgical resection of bladder cancer can be limited by acute side effects, whereas, RT, which offers a non-invasive treatment option with organ- and functional conservation, can cause long-term side effects. Bladder toxicity by RT mainly depends on the total irradiation dose, fraction size and tumour volume. Therefore, novel approaches are needed to improve clinical outcome. Local tumour hyperthermia is currently used either as an ablation therapy or in combination with RT to enhance anti-tumour effects. In combination with RT an increase of the temperature in the bladder stimulates the local blood flow and as a result can improve the oxygenation state of the tumour, which in turn enhances radiation-induced DNA damage and drug toxicity. Hyperthermia at high temperatures can also directly kill cells, particularly in tumour areas which are poorly perfused, hypoxic or have a low tissue pH. This review summarises current knowledge relating to the role of hyperthermia in RT to treat bladder cancer, the induction and manifestation of immunological responses induced by hyperthermia, and the utilisation of the stress proteins as tumour-specific targets for tumour detection and monitoring of therapeutic outcome.

Reactive oxygen species, heat stress and oxidative-induced mitochondrial damage. A review

In recent years there has been enormous interest in researching oxidative stress. Reactive oxygen species (ROS) are derived from the metabolism of oxygen as by-products of cell respiration, and are continuously produced in all aerobic organisms. Oxidative stress occurs as a consequence of an imbalance between ROS production and the available antioxidant defence against them. Nowadays, a variety of diseases and degenerative processes such as cancer, Alzheimer's and autoimmune diseases are mediated by oxidative stress. Heat stress was suggested to be an environmental factor responsible for stimulating ROS production because of similarities in responses observed following heat stress compared with that occurring following exposure to oxidative stress. This manuscript describes the main mitochondrial sources of ROS and the antioxidant defences involved to prevent oxidative damage in all the mitochondrial compartments. It also deals with discussions concerning the cytotoxic effect of heat stress, mitochondrial heat-induced alterations, as well as heat shock protein (HSP) expression as a defence mechanism.

Induction of cancerous stem cells during embryonic stem cell differentiation

Stem cell maintenance depends on their surrounding microenvironment, and aberrancies in the environment have been associated with tumorigenesis. However, it remains to be elucidated whether an environmental aberrancy can act as a carcinogenic stress for cellular transformation of differentiating stem cells into cancer stem cells. Here, utilizing mouse embryonic stem cells as a model, it was illustrated that environmental aberrancy during differentiation leads to the emergence of pluripotent cells showing cancerous characteristics. Analogous to precancerous stages, DNA lesions were spontaneously accumulated during embryonic stem cell differentiation under aberrational environments, which activates barrier responses such as senescence and apoptosis. However, overwhelming such barrier responses, piled-up spheres were subsequently induced from the previously senescent cells. The sphere cells exhibit aneuploidy and dysfunction of the Arf-p53 module as well as enhanced tumorigenicity and a strong self-renewal capacity, suggesting development of cancerous stem cells. Our current study suggests that stem cells differentiating in an aberrational environment are at risk of cellular transformation into malignant counterparts.

Synthesis and antioxidant capacity of 5-selenopyranose derivatives

Described is a convenient method for the syntheses of sulfur and selenium containing carbohydrate derivatives of L-gulodeoxynojirimycin and the corresponding C-5 epimer D-mannodeoxynojirimycin. The key step in the synthesis of the latter involves epimerisation of the C-5 hydroxyl group by an oxidation followed by stereo-selective reduction to obtain the desired D-sugar derivative. Both derivatives displayed a dose-dependent prevention of the oxidation of methionine residues on human plasma proteins induced by the inflammatory oxidant hypochlorous acid. The seleno-analogues were considerably more active than their thio-equivalents.

Tumour infiltrating host cells and their significance for hyperthermia

Much information can be gained by investigating the consequences of hyperthermia on individual cell populations in vitro, however the precise effects of such a therapeutic modality in vivo depend on the tumour microenvironment and the cellular composition therein. Although the direct cytotoxic effects of hyperthermia on tumour tissue can lead to an immediate reduction in tumour volume, long-term benefits to local and distal tumour recurrence will very much depend on the induction of immunity and the capacity of effector cells to traffic to tumours and elicit their cytotoxic functions. The immunological sequelae to hyperthermia are even more important in those instances when large tumour volumes preclude the delivery of appropriate thermal damage. The development of protective anti-tumour immunity requires a plethora of interactions and responses, the vast majority of which can be influenced by temperatures that are consistent with fever-like temperatures (39 degrees -40 degrees C), as well as hyperthermia treatment (<41 degrees C). This article reviews current knowledge relating to the effects of hyperthermia treatment on aspects of the induction and manifestation of immunological responses that are most pertinent to the development and maintenance of protective anti-tumour immunity.

Synthesis, characterization and reactivity of carbohydrate platinum(IV) complexes with thioglycoside ligands

Reactions of fac-[PtMe3(4,4'-R2bpy)(Me2CO)][BF4] (R = H, 1a; tBu, 1b) and fac-[PtMe3(OAc-kappa2O,O')(Me2CO)] (2), respectively, with thioglycosides containing thioethyl (ch-SEt) and thioimidate (ch-STaz, Taz = thiazoline-2-yl) anomeric groups led to the formation of the carbohydrate platinum(IV) complexes fac-[PtMe3(4,4-R2bpy)(ch*)][BF4] (ch* = ch-SEt, 8-14; ch-STaz, 15-23) and fac-[PtMe3(OAc-kappa2O,O')(ch*)] (ch* = ch-SEt, 24-28; ch-STaz = 29-35), respectively. NMR (1H, 13C, 195Pt) spectroscopic investigations and a single-crystal X-ray diffraction analysis of 19 (ch-STaz = 2-thiazolinyl 2,3,4,6-tetra-O-benzoyl-1-thio-beta-D-galactopyranose) revealed the S coordination of the ch-SEt glycosides and the N coordination of the ch-STaz glycosides. Furthermore, X-ray structure analyses of the two decomposition products fac-[PtMe3(bpy)(STazH-kappaS)][BF4] (21a) and 1,6-anhydro-2,3,4-tri-O-benzoyl-beta-D-glucopyranose (23a), where a cleavage of the anomeric C-S bond had occurred in both cases, gave rise to the assumption that this decomposition was mediated due to coordination of the thioglycosides to the high electrophilic platinum(IV) atom, in non-strictly dried solutions. Reactions of fac-[PtMe3(Me2CO)3][BF4] (3) with ch-SEt as well as with ch-SPT and ch-Sbpy thioglycosides (PT = 4-(pyridine-2-yl)-thiazole-2-yl; bpy = 2,2'-bipyridine-6-yl), having N,S and N,N heteroaryl anomeric groups, respectively, led to the formation of platinum(IV) complexes of the type fac-[PtMe3(ch*)][BF4] (ch* = ch-SEt, 36-40, ch-SPT 42-44, ch-Sbpy 45, 46). The thioglycosides were found to be coordinated in a tridentate kappaS,kappa2O,O, kappaS,kappaN,kappaO and kappaS,kappa2N,N coordination mode, respectively. Analogous reactions with ch-STaz ligands succeeded for 2-thiazolinyl 2,3,4-tri-O-benzyl-6-O-(2,2'-bipyridine-6-yl)-1-thio-beta-D-glucopyranoside (5h) resulting in fac-[PtMe3(ch-STaz)][BF4] (41, ch-STaz = 5h), having a kappa3N,N',N''coordinated thioglycoside ligand.

The tumor suppressor function of mitochondria: translation into the clinics

Recently, the inevitable metabolic reprogramming experienced by cancer cells as a result of the onset of cellular proliferation has been added to the list of hallmarks of the cancer cell phenotype. Proliferation is bound to the synchronous fluctuation of cycles of an increased glycolysis concurrent with a restrained oxidative phosphorylation. Mitochondria are key players in the metabolic cycling experienced during proliferation because of their essential roles in the transduction of biological energy and in defining the life-death fate of the cell. These two activities are molecularly and functionally integrated and are both targets of commonly altered cancer genes. Moreover, energetic metabolism of the cancer cell also affords a target to develop new therapies because the activity of mitochondria has an unquestionable tumor suppressor function. In this review, we summarize most of these findings paying special attention to the opportunity that translation of energetic metabolism into the clinics could afford for the management of cancer patients. More specifically, we emphasize the role that mitochondrial beta-F1-ATPase has as a marker for the prognosis of different cancer patients as well as in predicting the tumor response to therapy.

Thermosensitization by increasing intracellular acidity with amiloride and its analogs

PURPOSE

The major mechanisms that regulate the intracellular acidity of pHi in mammalian cells are the Na+/H+ exchange and HCO3-/Cl- exchange through the plasma membrane. The purpose of this study was to investigate the feasibility of increasing the thermosensitivity of tumors by increasing intracellular acidity with the use of drugs that inhibit the pHi regulatory mechanisms.

METHODS AND MATERIALS

The pHi of SCK tumor cells in vitro was determined with the fluorescence spectroscopy method. The thermosensitizing effects of the drugs on the cells in neutral (pH 7.2-7.5) and acidic (pH 6.6) media were determined by clonogenic assay. The thermosensitization of SCK tumors in vivo by the drugs was determined with the tumor growth delay and the in vivo-in vitro assay for clonogenic cells.

RESULTS

The pHi of SCK tumor cells in pH 7.2-7.5 media was similar to the media pH, while the pHi of the cells in pH 6.6 media was about 7.0. The pHi declined and the thermosensitivity of the tumor cells increased when the Na+/H+ exchange was inhibited with amiloride (3,5 diamino-6-chloro-N-(diaminomethylene) pyrazinecarboxamide) and its analogs, HMA (3-amino-6-chloro-5-(1-homopiperidyl)-N-(diaminomethylene) pyrazinecarboxamide) or EIPA (3-amino-6-chloro-5-(N-ethyl-N-isopropylamino)-N-diaminomethylene) pyrazinecarboxamide), especially in acidic medium. The potencies of HMA and EIPA to decrease the pHi and increase the thermosensitivity in vitro were more than 50 times greater than that of amiloride. DIDS (4,4-diiosothiocyanatostilbene-2,2'-disulfonic acid), an inhibitor of the Na(+)-dependent HCO3-/Cl- exchange, exerted little effect on the pHi and thermosensitivity of SCK cells in vitro, but it enhanced the effects of amiloride and its analogs. Amiloride and HMA also significantly enhanced the thermal effect on tumors in vivo, as judged by the tumor growth delay and also by the in vitro-in vivo assay for clonogenic cells. Combinations of DIDS with amiloride or HMA were more effective than either of them alone in increasing the thermal damage in vivo. As in vitro, HMA was far more potent than amiloride in increasing the thermosensitivity of tumor cells in vivo. However, EIPA was not effective in vivo, probably due to a rapid metabolic breakdown of the drug.

CONCLUSION

The drugs that interfere with the pHi regulatory mechanism significantly thermosensitized the tumor cells in vitro, particularly those in acidic media. The drugs were also effective in increasing the thermosensitivity of tumors. Because the interstitial environment in tumors is acidic relative to that in normal tissues, the thermosensitization by the drugs may be greater in tumors than that in normal tissues.

Potentiation of hyperthermia in a murine tumour by metabolic inhibitors rhodamine 123 and 2-deoxy-D-glucose or 5-thio-D-glucose

Rhodamine 123 injected into mice on 3 days consecutively before a single hyperthermia treatment (45 degrees C for 15 min) potentiated hyperthermia as evidenced by an increased mean tumour growth delay of a transplantable murine mammary adenocarcinoma (MTG-B). Addition of three daily injections of either 2-deoxy-D-glucose, or 5-thio-D-glucose, coordinated with the rhodamine 123, and administered before hyperthermia, resulted in an additional tumour growth delay, but not large enough to suggest an additional significant interaction between the two drugs and heat. This effect was obtained using doses of the glucose analogues which did not potentiate therapeutically when combined with heat without rhodamine 123. On the third day of treatments, rhodamine 123 or 5-thio-D-glucose, or the two drugs together, 60 min before heating, produced a longer growth delay compared with each combination treatment with drugs administered 15 min before heating. However, this effect was not significant. Results of these experiments suggest that in this murine tumour thermopotentiation can be attained by combining these two classes of metabolic inhibitors with hyperthermia.

Induction of thermotolerance and heat-shock protein synthesis during nutritional deprivation

Under various conditions of heating, H35 cells were submitted to acute nutritional deprivation by omitting a number of substrates (L15D medium). At 37 degrees C cell death starts after a lag-period of 3-5 h. During hypothermia cell death is delayed, whereas during hyperthermia it is accelerated especially as a result of thermosensitization. In L15D the ATP level decreases approximately 3 times faster in combination with hyperthermia than at 37 degrees C. In non-thermotolerant cells thermosensization is very high at 41 degrees C and decreases with increasing temperature; in thermotolerant cells it is comparatively decreased at 41 degrees C and increased at 42.5 degrees C and above. In response to a heat shock of 30 min at 42.5 degrees C only 10% of the cell population expresses acute thermotolerance after incubation at 37 degrees C in L15D as compared to nearly 100% in complete medium (L15C). Chronic development of thermotolerance appears to be even more repressed in the presence of L15D, which partly explains the high thermosensitization at 41 degrees C. Changes in the rate of protein synthesis for combinations of nutritional deprivation and hyperthermia show a correlation with the cell survival data. Development of acute thermotolerance in L15D is accompanied by an increase in heat-shock protein synthesis relative to total protein. At 41 degrees C in L15D no heat-shock protein induction could be detected. Of the omitted substrates only glutamine can effectively abolish thermosensitization and the effects of L15D on protein and heat-shock protein synthesis depending on the condition of the cells, thermotolerant or non-thermotolerant, and to a different extent for the various proteins considered.

Heat-induced damage to HeLa-S3 cells: correlation of viability, permeability, osmosensitivity, phase-contrast light-, scanning electron- and transmission electron-microscopical findings

The responses of HeLa S-3 to mild hyperthermia for relatively critical times at 43 and 45 degrees C were analysed in detail, including growth and colony-forming ability, permeability, osmotic sensitivity and microscopical appearances. For comparative purposes lower temperatures (e.g. 41 degrees C) and higher temperatures (50 and 55 degrees C) were used in some experiments. The evidence from many different aspects, including scanning and transmission electron microscopy, suggests that critical heat exposures do not per se cause severe membrane damage and loss of cell integrity, but changes quickly become manifest when cells are 'recovered' by returning to 37 degrees C. Attention is drawn to the ability of heat-treated cells to show osmotic-like swelling and restoration towards normal volume in medium of 30 per cent normal strength, which would not be expected on the hypothesis that hyperthermia primarily disrupts membrane structure and functioning. Ultrastructural changes during and after hyperthermia--including nucleolar changes, the appearance of perichromatin granules, the formation of electron-dense cytoplasmic clusters, and the development of intranuclear actin rods--corroborate and extend other findings. However, mitochondrial changes were found to be particularly significant, appearing early and correlating well with the loss of viability and metabolic functioning found after heat treatment. These include the early development of intramitochondrial dense granules, followed by vesicularization of the cristae, swelling of the intracristal spaces, myelin degeneration and the formation of bodies which could otherwise be mistaken for secondary lysosomes. The findings indicate the need for more intensive investigations of mitochondria and mitochondrial functioning in hyperthermia-induced cell damage, and their careful correlation with the 'recovery' of energy-dependent process in cells subsequently returned to 37 degrees C.

Rationale for use of local hyperthermia with radiation therapy and selected anticancer drugs in locally advanced human malignancies

The addition of local hyperthermia to radiation therapy has significantly improved the ability of oncologists to control superficial malignancies. Large tumours, tumours which cannot be heated adequately, and those situated in areas where surrounding normal tissues have decreased radiation tolerance, however, are difficult to eradicate even with this combination treatment. We believe that properly selected and scheduled anticancer drugs will add substantially to the efficacy of local hyperthermia and radiation. A review of the literature concerning the cytotoxic interactions of various anticancer agents with hyperthermia, with radiation and with relevant physiological parameters is presented. From this review, anticancer drugs which are good candidates for trimodality therapy are identified and a general approach to trimodality scheduling is suggested.

Sensitization of cultured Chinese hamster cells to 42 degrees C hyperthermia by pentalenolactone, an inhibitor of glycolytic ATP synthesis

The antibiotic pentalenolactone, a specific inhibitor of glyceraldehydephosphate dehydrogenase, was used to investigate the effect of glycolytic adenosine triphosphate (ATP) synthesis on the survival response of aerobic and hypoxic Chinese hamster cells treated with 42 degrees C hyperthermia. Data obtained with aerobic cells, incubated in balanced salt solutions supplemented with different substrates for ATP production, showed that 50 microM pentalenolactone blocked ATP synthesis via glycolysis but not by oxidative phosphorylation. The glycolytic inhibition was reversed upon transfer of the cells to antibiotic-free medium, and minimal cytotoxicity (less than 20 per cent) was observed. Hypoxic cultures were obtained by incubating dense cell suspensions (2 X 10(6)/ml) to produce metabolic oxygen depletion. Concomitant with the development of hypoxia, pentalenolactone-treated cells became ATP-depleted; cellular ATP levels were reduced by about 70-fold as compared to hypoxic cells in the antibiotic-free medium. The ATP-depleted cells were more sensitive to killing by hyperthermia. Comparison of the 42 degrees C survival curves for control and the antibiotic-treated hypoxic cells yielded a dose-modifying factor of 4 (5 per cent survival level). The results indicate that inhibition of glycolytic ATP synthesis, for example by pentalenolactone, can selectively sensitize hypoxic cells to the lethal effects of mild hyperthermia.

The effect of 5-thioglucose on the energy metabolism of Schistosoma mansoni in vitro

5-Thioglucose (5-TG) had a marked effect on the energy metabolism of Schistosoma mansoni in vitro: the conversion of external glucose into lactate by intact worms was severely inhibited. This inhibition of glycolysis was instantaneous, independent of the oxygen concentration and competitive with respect to glucose. Degradation of 0.5 mM external (14C-labelled) glucose was inhibited for 80% in the presence of 20 mM 5-TG. On the other hand the degradation of endogeneous glycogen to lactate was uninhibited. This shows that the inhibition of glucose breakdown occurred at the entrance of glucose into the cell and/or at the hexokinase reaction. It was demonstrated that 5-TG inhibited both the uptake of glucose and the activity of hexokinase. However, it was concluded that in the intact worm 5-TG blocked glycolysis by its competitive inhibition of hexokinase. In intact S. mansoni worms hexokinase is probably the rate-limiting enzyme of glycolysis. Krebs-cycle activity and lactate production do not occur at a fixed ratio: at lower rates of pyruvate formation Krebs-cycle activity was favoured.

Integration of allogeneic lymphocyte immunotherapy with short-course chemotherapy and hypoenergic hyperthermia: a "triple-threat" treatment for disseminated cancer

A strategy for treatment of disseminated cancer is proposed which unites short-course chemotherapy, local hyperthermia, and allogeneic lymphocyte immunotherapy, designed and timed so as to optimize their synergistic interactions. Short-course chemotherapy potentiates allogeneic lymphocyte immunotherapy, and in turn is potentiated by subsequent courses of local hyperthermia. Response to hyperthermia can be enhanced by measures which selectively inhibit tumor blood flow, impair tumor energy metabolism, and produce tumor acidification; these include induction of prolonged hyperglycemia, and administration of selectively activated "hypoenergic" agents which inhibit or uncouple tumor respiration. It is anticipated that these methods will enable a significant advance in the control of metastasized solid tumors.

Effect of hyperthermia on hypoxic cell fraction in tumor

The effect of hyperthermia on the proportion of hypoxic cells in SCK mammary tumor of A/J mice was investigated. About 45% of clonogenic cells in the unheated control tumor were radiobiologically hypoxic. Upon heating with a 43.5 degree C water bath for 30 min, the proportion of hypoxic cells increased and then decreased: it was 95% at 5 hr and 60% at 12 and 24 hr after heating. Despite the increase in the proportion of hypoxic cells 5 hr after heating, the absolute number of hypoxic cells in the tumors at this time was significantly smaller than that in the unheated control tumors because of a decrease in the total number of surviving tumor cells. The initial increase in the proportion of hypoxic cells after heating may be attributed mainly to vascular occlusion. Proliferation of cells in the oxic area, and thus an increase in oxic cell number, appears to account for the decline in the proportion of hypoxic cells from 5 hr after heating.

Energy and misonidazole toxicity: the effects of 5-thio-D-glucose

Cell inactivation and DNA damage (single-strand breaks) were used to study the effects of inhibitors of anaerobic glucose oxidation on the toxicity of misonidazole to hypoxic Chinese hamster cells. Citrate and 2-deoxyglucose produced no effects on the toxicity. 5-thio-D-glucose (5-TG) protected cells of the CH2B2 line to some extent (SSB decreased by about 30%). In the CHO lines used (wild, and ethylmethanesulfonate-sensitive mutants), 5-TG had varied effects. Non-protein sulfhydryl (NPSH) levels were measured in all lines. Cells with lower NPSH levels are more sensitive to misonidazole; these are the cells which are protected by 5-TG. Cell line variations must be considered when studying interactions between a drug and other forms of treatment as possible treatments of cancer.

Comparison of the cytotoxicity of 5-thio-D-glucose and misonidazole on hypoxic cells in vitro

The cytotoxicity of 5-thio-D-glucose (5-TG) and misonidazole (MISO) on hypoxic cells in vitro was compared, and the combined effect of these two compounds was investigated. The cytotoxicity of 5-TG on hypoxic SCK mammary carcinoma cells of mice was markedly greater than that of MISO. However, MISO was more toxic than was 5-TG to P815-X2 mastocytoma cells of mice. The elevation of temperature from 37.5 degrees C to 40.0 degrees C during incubation with drugs greatly enhanced the cell death. The thermal enhancement of cytotoxicity of 5-TG to mastocytoma cells appeared to be greater than that of MISO. Preliminary studies indicated that the combined effect of 5-TG and MISO is additive, suggesting the intracellular targets or cytocidal mechanisms of these two compounds may be different.

The combined effects of oxygen tension, X radiation and 5-thio-D-glucose on the survival of mammalian cells

The glucose analogue 5-thio-D-glucose (5-TG) is toxic to hypoxic cells but does not affect aerated cells. Toxicity is markedly dependent upon oxygen tension: exposure of Chinese hamster cells to 5 mM 5-TG and 50 ppm O2 (in the overlying atmosphere) results in a survival of 0.01 in six hours, whereas increasing the oxygen to 100 ppm causes the survival to increase to about 0.9. The combined effect of X rays and 5-TG is to reduce the survival of hypoxic cells to a level far below that attainable with either agent alone. Cells made hypoxic with 5 ppm O2 have 0.1 survival after three hours exposure to 5 mM 5-TG. The same cells have a 0.5 survival when given a dose of 1000 rad. When the x-irradiation is given at the end of a three-hour exposure to 5-TG, the survival is reduced to 0.0055.

Enhancement of hyperthermia-induced cytotoxicity upon ATP deprivation

The combined effects of hyperthermia and uncouplers of oxidative phosphorylation (dinitrophenol (DNP) or m-chlorocarbonylcyanide phenyl-hydrazone (CCCP) or 5-thio-d-glucose (5-TG) on mammalian cell survival were studied in vitro. Uncouplers were toxic towards cells treated under aerobic conditions at 41 degrees C, whereas 5-TG potentiated the effect of hyperthermia in the case of hypoxic cells. In aerobic conditions the intracellular ATP concentration was decreased upon action of uncouplers, and similar changes occurred in hypoxic cells treated with 5-TG. The results suggest that the ATP deprivation enhances the cell killing by hyperthermia.

The role of energy in hyperthermia-induced mammalian cell inactivation: a study of the effects of glucose starvation and an uncoupler of oxidative phosphorylation

When cultured Chinese hamster cells were exposed to 43 degrees C hyperthermia, effects due to glucose deprivation and to the presence of the uncoupler of oxidative phosphorylation, carbonylcyanide-3-chlorophenylhydrazone, during the 43 degrees C treatment proved to be strongly accelerated compared to the effects at normal temperature (37 degrees C). This strongly indicates that the availability of energy plays an important role in the response of these cells to hyperthermia. One of the reasons cells die after hyperthermia may be a lethal lack of energy. Cells heated before glucose deprivation were able to maintain viability for a longer period during deprivation than cells without the preheat treatment. As the cells might develop thermotolerance after the heat exposure, this suggests that cells in the thermotolerant state use energy in a more economical way.

The extra nuclear control of mitosis & cell function. A theory of cellular organisation

There is evidence to suggest that the extra nuclear cell constituents are the part of the cell which contains all the biochemical mechanisms responsible for implementing all cell functions. These functions include control of cell division, growth, response to injury, replacement of effete cells, maintenance of anatomical and spatial cellular relations and specific cellular function and structure. The energy to perform these functions is derived from the aerobic metabolism of glucose. The energy required for nuclear division appears to be wholly or partly derived from the anaerobic metabolism of glucose. Ethyl alcohol interferes with the aerobic metabolic pathways and thus disrupts or diminishes all aerobically activated cell functions. The speed of all activities motivated by aerobic glycolysis can be increased by appropriate electrical stimulations delivered from any of a range of electromagnetic radiation frequencies tested. In addition to the stimulant effect on aerobic metabolic processes, 434 MHz can stimulate the anaerobic glucose metabolism of cancer with consequent stimulation of cancer growth rate. 434 MHz appears to deliver energy to the anaerobic cancer metabolism by causing a resonance phenomenon amongst one or more of the substrates which comprise the first few stages of glycolysis. This phenomenon permits the selective delivery of electromagnetic radiation energy to cancer cells which, if sufficiently intense, causes injury to cancer cells without harm to the normal cells except when the latter are in the phase of anaerobic metabolism which occurs at some stage of the mitotic cycle. Streptokinase, ethanol and glucose analogues increase the lethal effects on cancers undergoing therapy with 434 MHz radiation and observations of such responses suggest a theoretical basis to explain the rare spontaneous remissions of human cancer. Cancer appears to protect its glucose supplies by elevating the blood glucose levels above normal and by some mechanism which reduces the effectiveness of the body's control of its fasting glucose level. The serum fibrinogen level rises when cancer involves the abdominal viscerae, particularly the liver. A raised serum fibrinogen level appears to be a direct indication that the liver must be included in the treatment regime if longer survival is desired. If the level cannot be corrected then death of that individual appears assured.