Whole body hyperthermia: a potent radioprotector in vivo

Micronuclei formation in rainbow trout cells exposed to multiple stressors: Morpholine, heat shock, and ionizing radiation

Discharges from industrial cooling water systems can include low levels of morpholine (a chemical pH regulator and corrosion inhibitor), as well as transiently higher temperature effluent water which present a potential source of environmental impact to aquatic biota. The effects of environmental levels of morpholine or heat shock (HS) treatment alone and in combination with a challenge high-dose of ¹³⁷Cs ionizing radiation were studied using the cytokinesis block micronucleus assay in a rainbow trout cell line (RTG-2). Morpholine treatment of 10 or 100mgL^-1 alone produced no significant effects, and no interaction was observed in combination with 7.75Gy radiation. A 9°C magnitude HS treatment alone significantly increased micronuclei formation. A synergistic response was observed when 9°C HS was combined with 7.75Gy radiation, with 15% more cells containing 3 or more micronuclei than the sum of each individual stressor. A synergistic increase in the average number of micronuclei was observed when morpholine and a 9°C HS were co-treated. These results indicate that morpholine at environmentally-relevant levels does not impact micronuclei formation or cell cycle progression however 9°C HS may be of potential concern both alone and in combination with other stressor treatments.

Heat stroke

Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling.

Evaluation of gamma ray-induced gastrointestinal tract morphological and proliferative activity changes in rhesus monkeys

To provide support for future pharmacology and preclinical studies, we have established a stable nonhuman primate animal model to demonstrate the histopathological changes in the gastrointestinal tract following gamma ray irradiation. In this study, 12 healthy rhesus monkeys were divided into 2 groups (control and radiation groups). Animals in the radiation group were exposed to gamma rays (cobalt 60 source) at a dose level of 6.5 Gy total body irradiation bilaterally (i.e. 3.25 Gy on each side). Control animals were sham exposed using identical procedures. After a 5-day in-life observation period, gastrointestinal tract tissues (esophagus, stomach, duodenum, jejunum, ileum, colon, and rectum) were collected and fixed in 10% neutral-buffered formalin for subsequent hematoxylin and eosin and 5-bromo-2-deoxyuridine (BrdU) immunohistochemistry processing. The results showed that the esophagus was undergoing degeneration without obvious inflammatory changes, while the stomach and duodenum exhibited both degeneration and inflammation. From the jejunum to the rectum, late-stage inflammation with glandular regeneration, as well as a high-level BrdU labeling index, was present.

Effects of lethal dose of γ-radiation and partial body hyperthermia on Wistar rats

PURPOSE

The radioprotectors currently available are generally poorly tolerated in human beings; thus, their use has been restricted due to their side effects and their limited clinical tolerance. In a search for fewerand/or without side effects agents, the radioprotective effects of partial body hyperthermia (PBH) were tested on Wistar rats of both sexes at different ages.

MATERIALS AND METHODS

PBH (43 °C, 1 h) was carried out by immersion of each animal's lower parts and legs in a thermostatically controlled water bath 20 h prior to irradiation with a lethal single exposure dose of 9 Gy of gamma irradiation. Irradiated PBH pretreated animals were monitored for 30 days post-irradiation and survival percentages were calculated.

RESULTS

The data obtained provide evidence that PBH treatment prolonged the irradiated rats' lifespans and the mortality rates varied significantly with animal age and sex. In addition, PBH treatment significantly enhanced bone marrow recovery of irradiated rats of both genders.

CONCLUSIONS

Partial body hyperthermia prior to radiation proved to have beneficial effects on gamma irradiated rats.

Standard sub-thermoneutral caging temperature influences radiosensitivity of hematopoietic stem and progenitor cells

The production of new blood cells relies on a hierarchical network of hematopoietic stem and progenitor cells (HSPCs). To maintain lifelong hematopoiesis, HSPCs must be protected from ionizing radiation or other cytotoxic agents. For many years, murine models have been a valuable source of information regarding factors that either enhance or reduce the survival of HSPCs after exposure of marrow to ionizing radiation. In a recent series of studies, however, it has become clear that housing-related factors such as the cool room temperature required for laboratory mice can exert a surprising influence on the outcome of experiments. Here we report that the mild, but chronic cold-stress endured by mice housed under these conditions exerts a protective effect on HSPCs after both non-lethal and lethal doses of total body irradiation (TBI). Alleviation of this cold-stress by housing mice at a thermoneutral temperature (30°C) resulted in significantly greater baseline radiosensitivity to a lethal dose of TBI with more HSPCs from mice housed at thermoneutral temperature undergoing apoptosis following non-lethal TBI. Cold-stressed mice have elevated levels of norepinephrine, a key molecule of the sympathetic nervous system that binds to β-adrenergic receptors. We show that blocking this signaling pathway in vivo through use of the β-blocker propanolol completely mitigates the protective effect of cold-stress on HSPC apoptosis. Collectively this study demonstrates that chronic stress endured by the standard housing conditions of laboratory mice increases the resistance of HSPCs to TBI-induced apoptosis through a mechanism that depends upon β-adrenergic signaling. Since β-blockers are commonly prescribed to a wide variety of patients, this information could be important when predicting the clinical impact of HSPC sensitivity to TBI.

Alteration of cytokine profiles in uranium miners exposed to long-term low dose ionizing radiation

Objective. The aim of the study is to estimate the immune function through cytokine profiles in sera of uranium mines. Methods. Antibody arrays were used to detect 50 cytokines in sera of uranium miners. Miners who had continuously worked underground for <5 years were treated as control group and those who worked for ⩾5 years as experimental group. Results. Of 28 measurable cytokines, the release of IL-1α, IL-1RI, IL-15, IL-3, and IP-10 were significantly upregulated in the experimental group, and no cytokine was found significantly downregulated. Other proinflammatory cytokines such as IFN-γ, IL-10, IL-6, and TNFα levels were slightly upregulated in the experimental group. With adjustment to age, BMI, and cigarette smoking, IL-1α and IL-3 levels increased significantly with underground time. Conclusion. Alteration of cytokine profiles in this study may indicate persistent inflammatory responses in uranium miners exposed to long-term low doses radiation.

Elevating body temperature enhances hematopoiesis and neutrophil recovery after total body irradiation in an IL-1-, IL-17-, and G-CSF-dependent manner

Neutropenia is a common side effect of cytotoxic chemotherapy and radiation, increasing the risk of infection in these patients. Here we examined the impact of body temperature on neutrophil recovery in the blood and bone marrow after total body irradiation (TBI). Mice were exposed to either 3 or 6 Gy TBI followed by a mild heat treatment that temporarily raised core body temperature to approximately 39.5°C. Neutrophil recovery was then compared with control mice that received either TBI alone heat treatment alone. Mice that received both TBI and heat treatment exhibited a significant increase in the rate of neutrophil recovery in the blood and an increase in the number of marrow hematopoietic stem cells and neutrophil progenitors compared with that seen in mice that received either TBI or heat alone. The combination treatment also increased G-CSF concentrations in the serum, bone marrow, and intestinal tissue and IL-17, IL-1β, and IL-1α concentrations in the intestinal tissue after TBI. Neutralizing G-CSF or inhibiting IL-17 or IL-1 signaling significantly blocked the thermally mediated increase in neutrophil numbers. These findings suggest that a physiologically relevant increase in body temperature can accelerate recovery from neutropenia after TBI through a G-CSF-, IL-17-, and IL-1-dependent mechanism.

Winner of the 2007 Society for Thermal Medicine Young Investigator Award. Fever-range whole body hyperthermia prevents the onset of type 1 diabetes in non-obese diabetic mice

PURPOSE

Type 1 diabetes (T1D) is an autoimmune disease in which the insulin producing beta cells of the pancreatic islets are destroyed by cytotoxic T lymphocytes (CTLs). It has been demonstrated that the injection of complete Freund's adjuvant (CFA) can prevent disease onset in non-obese diabetic (NOD) mice. This effect has been attributed to CFA-enhanced natural killer (NK) cell mediated control of autoimmune CTLs. Fever-range whole body hyperthermia (FR-WBH) has also been shown to stimulate NK cell cytotoxicity. This led to the hypothesis that FR-WBH can prevent disease onset in NOD mice by a thermally regulated mechanism.

METHODS

FR-WBH or mock treatment was administered weekly until the NOD mice reached 32 weeks of age. Blood glucose levels were monitored weekly, with measurements > or =33.5 mM indicating onset of diabetes, at which time the mice were euthanized for histological and cellular analyses.

RESULTS

Weekly FR-WBH prevented the onset of T1D in NOD mice and this effect correlated with increased NK cell cytotoxicity and control of blood glucose concentration. Histological analysis revealed significantly fewer lymphocytes infiltrating the pancreatic islets of FR-WBH treated mice than those of untreated mice, suggesting a relationship between thermally induced protection of beta cells and their ability to regulate blood glucose concentrations.

CONCLUSIONS

These studies show, for the first time, that mild systemic hyperthermia can prevent the generation of T1D in a clinically relevant mouse model. Further study of the thermally sensitive aspects of immunoregulation could lead to the development of heat-based therapies for the prevention or treatment of autoimmune diseases.

Hsf1-mediated stress response can transiently enhance cellular radioresistance

To elucidate how the heat-shock transcription factor 1 (Hsf1)-mediated stress response affects cellular radioresistance, mouse embryo fibroblasts with Hsf1-gene knockout (Hsf1(-/-) cells) or with normal wild-type Hsf1 expression (Hsf1 wild-type cells) were preconditioned by heating (43 degrees C, 30 min) without or with quercetin (an inhibitor of Hsf1) and then exposed to gamma radiation (4 or 6 Gy). Some cell samples were infected with virus-based vectors to overexpress the constitutively active (mutant) form of Hsf1 or individual heat-shock proteins (Hsps). The heat preconditioning transiently up-regulated the Hsp levels in Hsf1 wild-type cells and significantly improved their postirradiation survival; these effects could be abolished by quercetin or simulated (without preheating) by the Hsf1 overexpression. In contrast, no enhanced radioresistance was found in heat-preconditioned Hsf1(-/-) cells that were unable to trigger Hsf1-mediated Hsp induction after heating. However, when the constitutively active Hsf1 was overexpressed in Hsf1(-/-) cells, the latter accumulated stress-inducible Hsps and became more radioresistant like heat-preconditioned Hsf1 wild-type cells. The overexpression of Hsp70 or/ and Hsp27 also enhanced radioresistance of both cell cultures. Thus the preirradiation stress response resulting in the intracellular Hsp accumulation can improve survival of severely irradiated mammalian cells.

Pharmacological induction of Hsp70 protects apoptosis-prone cells from doxorubicin: comparison with caspase-inhibitor- and cycle-arrest-mediated cytoprotection

Selective modulation of cell death is important for rational chemotherapy. By depleting Hsp90-client oncoproteins, geldanamycin (GA) and 17-allylamino-17-demethoxy-GA (17-AAG) (heat-shock protein-90-active drugs) render certain oncoprotein-addictive cancer cells sensitive to chemotherapy. Here we investigated effects of GA and 17-AAG in apoptosis-prone cells such as HL60 and U937. In these cells, doxorubicin (DOX) caused rapid apoptosis, whereas GA-induced heat-shock protein-70 (Hsp70) (a potent inhibitor of apoptosis) and G1 arrest without significant apoptosis. GA blocked caspase activation and apoptosis and delayed cell death caused by DOX. Inhibitors of translation and transcription and siRNA Hsp70 abrogated cytoprotective effects of GA. Also GA failed to protect HL60 cells from cytotoxicity of actinomycin D and flavopiridol (FL), inhibitors of transcription. We next compared cytoprotection by GA-induced Hsp70, caspase inhibitors (Z-VAD-fmk) and cell-cycle arrest. Whereas cell-cycle arrest protected HL60 cells from paclitaxel (PTX) but not from FL and DOX, Z-VAD-fmk prevented FL-induced apoptosis but was less effective against DOX and PTX. Thus, by inducing Hsp70, GA protected apoptosis-prone cells in unique and cell-type selective manner. Since GA does not protect apoptosis-reluctant cancer cells, we envision a therapeutic strategy to decrease side effects of chemotherapy without affecting its therapeutic efficacy.

Effect of mild whole body hyperthermia on cytotoxic action of N-methyl-N'-nitro-N-nitrosoguanidine in Swiss mice

Studies were carried out to ascertain the efficacy of mild whole body hyperthermia (WBH) as a modifier of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) cytotoxicity in mice. Adult Swiss male mice, 6-8 weeks old, weighing about 25 g were exposed to mild WBH (39 degrees C, 1 h) in a precision temperature controlled environmental chamber maintained at 50-60% relative humidity. Twenty-four hours after treatment, animals were administered with different doses of MNNG either by intraperitoneal (i.p.) injections or by feeding through drinking water and were monitored for survival. The studies revealed that the exposure of animals to mild WBH, 24 h prior to MNNG administration results in an increase in survival and recovery in mean body weight compared with those administered with MNNG only. This suggests that prior WBH treatment can effectively reduce the MNNG cytotoxicity in mice.

Regulation of immune activity by mild (fever-range) whole body hyperthermia: effects on epidermal Langerhans cells

Inflammation of the skin and systemic fever, both of which occur with injury or infection, include a hyperthermic component that many believe constitutes a physiological stress. Such increases in local or systemic body temperature may also have a regulatory effect on immune function. Langerhans cells (LCs), the dendritic cells of the skin, continuously monitor the extracellular matrix of the skin by taking up particles and microbes that they then carry to draining lymph nodes for presentation to T lymphocytes. We hypothesize that the thermal element of inflammation and/or fever may help regulate the activation and migration of LCs out of the epidermis. To test this hypothesis, Balb/ c mice were exposed to a mild (39.8 degrees C +/- 0.2 degrees C), long-duration (6 hours) whole body hyperthermia (WBH) treatment, which mimics the thermal component of fever. The number of LCs and their morphology were analyzed at various time points up to 7 days after the initiation of WBH. The LCs of the ear epidermis were visualized using a fluorescein isothiocyanate-conjugated antibody specific for the major histocompatibility complex (MHC) class II molecule and confocal microscopy. Although MHC class II staining was diffuse on the surface of the LC body and dendritic extensions of both WBH and control samples, the WBH-treated LCs exhibited a more punctate morphology with fewer dendritic processes compared with control LCs. A significant decrease in the number of LCs was also observed 1 to 5 days after WBH treatment. Furthermore, in vitro heating of Balb/c ear skin cultures at 40 degrees C for 6 to 8 hours enhanced the numbers of viable LCs that migrated into the culture wells. These results suggest that WBH treatment stimulates epidermal LCs in the absence of foreign antigen.

Regulation of immune activity by mild (fever-range) whole body hyperthermia: effects on epidermal Langerhans cells

Inflammation of the skin and systemic fever, both of which occur with injury or infection, include a hyperthermic component that many believe constitutes a physiological stress. Such increases in local or systemic body temperature may also have a regulatory effect on immune function. Langerhans cells (LCs), the dendritic cells of the skin, continuously monitor the extracellular matrix of the skin by taking up particles and microbes that they then carry to draining lymph nodes for presentation to T lymphocytes. We hypothesize that the thermal element of inflammation and/or fever may help regulate the activation and migration of LCs out of the epidermis. To test this hypothesis, Balb/ c mice were exposed to a mild (39.8 degrees C +/- 0.2 degrees C), long-duration (6 hours) whole body hyperthermia (WBH) treatment, which mimics the thermal component of fever. The number of LCs and their morphology were analyzed at various time points up to 7 days after the initiation of WBH. The LCs of the ear epidermis were visualized using a fluorescein isothiocyanate-conjugated antibody specific for the major histocompatibility complex (MHC) class II molecule and confocal microscopy. Although MHC class II staining was diffuse on the surface of the LC body and dendritic extensions of both WBH and control samples, the WBH-treated LCs exhibited a more punctate morphology with fewer dendritic processes compared with control LCs. A significant decrease in the number of LCs was also observed 1 to 5 days after WBH treatment. Furthermore, in vitro heating of Balb/c ear skin cultures at 40 degrees C for 6 to 8 hours enhanced the numbers of viable LCs that migrated into the culture wells. These results suggest that WBH treatment stimulates epidermal LCs in the absence of foreign antigen.

Comparison of the effects of two different whole body hyperthermia protocols on the distribution of murine leukocyte populations

Two predominant WBH protocols presently being used in clinical trials include a low temperature, long duration (LL) WBH, where core body temperature is raised to 39.5-40 degrees C for 6h or more, and a high temperature, short duration (HS) WBH, where core body temperature is raised to 41.8 degrees C for up to 2h. Here, the effects of LL-WBH and HS-WBH on leukocyte populations in the blood, spleen, lymph node (LN) and peritoneal cavity (PerC) of Balb/c mice were compared using flow cytometry. The total numbers of peripheral blood leukocytes decreased up to 2-fold immediately after LL-WBH, reflecting a decrease of lymphocyte numbers compared to controls. In contrast, the numbers of blood leukocytes are increased 2.7-fold immediately after HS-WBH compared to controls, reflecting an increase in lymphocytes, monocytes and granulocytes. After both LL- and HS-WBH treatment, leukocyte numbers in the spleen are decreased approximately 2-fold, again reflecting decreases in lymphocyte numbers. In the PerC, total numbers of leukocytes are also significantly decreased (2-fold) during LL-WBH but not HS-WBH. Total numbers of leukocytes in the LNs were unaffected by both LL- and HS-WBH. Overall, these data reveal differential effects of the LL- and HS-WBH protocols on leukocyte populations in the blood, spleen, LN and PerC of Balb/c mice.

Tumour cell kinetics as predictors of response in canine lymphoma treated with chemotherapy alone or combined with whole body hyperthermia

Kinetic parameters including potential doubling time (Tpot), duration of S phase (Ts), labelling index (LI), and DNA index (DI) were obtained from 42 dogs with previously untreated lymphoma. Standard flow cytometric techniques using BrdUrd were employed. All dogs were treated with L-asparaginase and remission was induced in 26 dogs, which were then randomized to receive chemotherapy only (doxorubicin [DOX] alone or with lonidamine) or chemotherapy plus whole body hyperthermia (WBH). Dogs were treated every 3 weeks for up to five treatments and evaluated every 3 weeks for evidence of tumour recurrence. Within this subset of animals there was no difference in outcome based on treatment group. Median values for Tpot, Ts and LI were 3.4 days, 7.23 h and 12.49%, respectively. Dogs that had tumours with LI > or = 20% had a shorter time until recurrence than dogs with tumours characterized by LI < 20%. In dogs treated only with chemotherapy, dogs bearing tumours with longer than median Tpot and Ts values and lower than median LI had significantly longer remission duration than dogs with more rapidly proliferating tumours. Dogs treated only with chemotherapy, which had longer than median Tpot and Ts values and lower than median LI, had significantly longer remission duration than all other dogs in the study. The mechanisms in which kinetics are associated with response to chemotherapy are not clear and vary depending on tumour type and treatment regimen. More work is needed to understand factors involved in cell killing during in vivo hyperthermia.

Delayed death after uncomplicated hot tub bathing in dogs and monkeys

Prolonged heat exposure as in hot tub bathing, although frequently practiced, has occasionally resulted in fatalities that have been explained by an underlying disease. We explored the tolerance of hot water immersion of 60 min in five previously healthy animals (three dogs and two monkeys). With invasive monitoring, experimental body immersion in water at 40-45 degrees C, with core temperature kept at 40-42 degrees C for 60 min, caused no significant cardiovascular, pulmonary or metabolic changes during hyperthermia or for 2 h after return to normothermia. Then secondary deterioration occurred with progressive hypotension, petechial hemorrhages throughout the viscera, gross gastrointestinal hemorrhages and irreversible (hypovolemic) shock. These effects occurred earlier in the monkeys than in the dogs. This shock state did not respond to standard resuscitation attempts. One dog survived the secondary shock state. We conclude that during and after hot tub immersion, good initial tolerance to heat exposure can, several hours after return of normothermia, result in delayed secondary deterioration and death. We recommend that the mechanism of this delayed shock state with apparent capillary leakage be clarified.

Cytokine production after whole body and localized hyperthermia

The levels of TNF, IL-1 and IL-6 in circulating blood female WAG/Ry rats were assessed in relation to treatment with localized hyperthermia of the right hind leg or with whole-body hyperthermia (WBH). After a localized treatment for 30 min at 43 or 44 degrees C no detectable increase in levels of IL-6 or TNF was obtained. Hyperthermia for 30 min at 45 degrees C led to an elevated level of IL-6 of 19.4 +/- 5.2 U/ml above the control level of 24 h after treatment. Levels of IL-1 were never higher than those in control animals that received only anaesthesia. Anaesthesia induced a peak level of approximately 131 U/ml IL-1 6 h after treatment. Serum levels of IL-1 and IL-6 are enhanced after WBH. IL-1 reaches a peak level already during WBH about 15 after reaching 41.5 degrees C. IL-6 levels were not enhanced during WBH but 1 h after WBH a clear peak was observed. Anaesthesia with sham WBH did not lead to enhanced IL-6 levels but enhanced IL-1 levels were clearly detected. We did not detect TNF in any sample after WBH. It is concluded from the present results that IL-6 is not induced by a 'standard' treatment of localized hyperthermia as used in oncotherapy (i.e. 60 min at 43 degrees C) to such a high level locally that this is reflected in increased levels in circulating blood. WBH at clinically relevant temperatures leads to enhanced levels of IL-1 and IL-6. The difference in IL-6 response after WBH or localized hyperthermia probably is related to the fact that in WBH also the bone marrow is treated. This may lead to stimulation of this important stem cell compartment of the peripheral blood. The sequence of appearance of IL-1 and IL-6 after hyperthermia is akin to the sequence in an inflammatory response. However, the experiments with sham treatment show that IL-1 may appear in the circulating blood not followed by IL-6. These results indicate that enhanced IL-1 levels may reflect a stress reaction of the animal related to the (sham) treatment. Enhanced levels of IL-1 after WBH correlate with enhanced levels of ACTH in the circulating blood.

Influence of heat shock protein 70 and metallothionein induction by zinc-bis-(DL-hydrogenaspartate) on the release of inflammatory mediators in a porcine model of recurrent endotoxemia

The manipulation of stress gene expression by heavy metals provides protection against the lethal effects of endotoxemia in murine models of septic shock. Recent in vitro studies with alveolar macrophages or monocytes show that induction of the stress response in these cells is followed by a decreased liberation of major cytokines [tumor necrosis factor-alpha (TNF alpha) and interleukin-1 (IL-1)] after endotoxin challenge. These findings suggest that the increased resistance to endotoxin in vivo after stress protein induction could be explained by an altered pattern of inflammatory mediator release. Therefore, we measured the time course of thromboxane-B2 (TxB2), 6-keto-PGF1 alpha, platelet activating factor (PAF), TNF alpha, interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) formation with and without induction of the stress response in an established porcine model of recurrent endotoxemia (Klosterhalfen et al., Biochem Pharmacol 43: 2103-2109, 1992). Induction of the stress response was done by a pretreatment with Zn2+ (25 mg/kg zinc-bis-(DL-hydrogenasparate = 5 mg/kg Zn2+). Pretreatment with Zn2+ prior to lipopolysaccharide (LPS) infusion induced an increased heat shock protein 70 and metallothionein expression in the lungs, liver, and kidneys and increased plasma levels of TNF alpha, IL-1 beta, IL-6, and TxB2 as opposed to untreated controls. After LPS infusion, however, pretreated animals showed significantly decreased peak plasma levels of all mediators as opposed to the untreated group. The time course of mediator release was identical with the decreasing and increasing three peak profiles described previously. Hemodynamic data presented significantly decreased peak pulmonary artery pressures and significantly altered hypodynamic/hyperdynamic cardiac output levels in the pretreated group. In conclusion, the data show that the induction of stress proteins by Zn2+ could be a practicable strategy to prevent sepsis.

Phase I evaluation of mitoxantrone alone and combined with whole body hyperthermia in dogs with lymphoma

The maximum tolerated dose of mitoxantrone (MX) administered alone or combined with whole body hyperthermia (WBH) was determined in this nonrandomized, prospective study in dogs with lymphoma. MX was administered to 53 dogs every three weeks for a total of six treatments unless progressive disease or persistent, severe toxicity developed. Fifty dogs were evaluable (MX alone n = 30, MX/WBH n = 20). MX was administered as a 1 h infusion at the onset of the plateau phase of WBH in dogs treated with combined therapy. Dogs were evaluated weekly between treatments for the first four treatments with physical examination and complete blood counts to define acute and cumulative toxicity. Dogs were evaluated every three weeks for tumour response until relapse. The maximum tolerated dose (MTD) was defined as that dose in each group that resulted in a 50% incidence of moderate or severe toxicity as estimated from logistic regression analysis of the toxicity data. Myelosuppression was the only toxicity observed. Neutropenia was equal in frequency and severity between treatment groups. Thrombocytopenia was not observed in any dog receiving MX/WBH but occurred in 13% of dogs treated with MX alone. The MTD for MX +/- WBH was 6.1 +/- 0.6 and 6.5 +/- 0.8mg/M2 respectively. A steeper dose response relationship was observed in dogs receiving combined therapy compared to dogs treated with MX alone suggesting WBH may improve the uniformity of patient response to chemotherapy. We concluded that MX may be administered without dose reduction to dogs undergoing WBH and that MX should be evaluated more thoroughly in future thermochemotherapy studies.

Water bath hyperthermia is a simple therapy for psoriasis and also stimulates skin tanning in response to sunlight

An eight week trial, involving superficial hyperthermia delivered biweekly via simple water bath immersion, was tested for its ability to clear mild to moderate psoriatic lesions. Seven patients were treated and three cases rapidly improved. In the remaining patients, the treatment frequency was increased to alternate days; two cases improved significantly, one patient showed a partial response, and the fourth had no visible change (this was the only patient taking concurrent drug therapy--etretinate). In addition to resolving psoriatic lesions, water bath hyperthermia also reduced edema (swelling) and relieved pruritus (itching) in all patients, both during the treatment period and for up to several months after lesions had returned. Lesion reappearance occurred within one to three months after the last heat treatment. We retreated one patient and produced a second complete remission. These results indicate that simple repetitive water bath hyperthermia alone is effective in the treatment of psoriatic lesions in heatable locations. An unexpected side effect was enhanced melanin content (tanning) in all areas where hyperthermia treated skin was exposed to sunlight.

Interactions between photolyase and dark repair processes in Chlamydomonas reinhardtii

The participation of DNA photolyase in dark repair processes has been reported in some heterotrophic organisms. To assess the role of photolyase in dark repair in photoautotrophs, double mutants of Chlamydomonas reinhardtii deficient in dark repair and photoreactivation were constructed and assayed for UV sensitivity in different posttreatment light conditions (with or without subsequent photoreactivation). We found that a functional PHR1 gene enhanced dark survival in the excision deficient (uvs9, uvs12) and in the recombination deficient (uvs10) genetic backgrounds but failed to do so in the strain deficient in a repair pathway other than excision and recombination (uvs13). Therefore we can conclude that photolyase may stimulate dark repair processes in C. reinhardtii also via pathway(s) other than nucleotide excision repair. The fact that some of the double mutants deficient in dark repair and photoreactivation survived better in the light than in the dark supports the idea that additional photorepair might be active and may enhance survival in a specific genetic background.

Potential radioprotective agents--V. Melatonin analogs. Oral activity of p-aminopropiophenone and its ethylene ketal

Seven new amides of 5-methoxytryptamine were synthesized and tested for radioprotective activity in mice. One of them, the heptafluorobutyramide 4, is moderately active (57% survivors), the rest demonstrate little or no activity. Of twelve compounds that had been found to exhibit high radioprotective activity by ip injection, only two [p-aminopropiophenone (9) and its ethylene ketal 8] retain that high activity (92-95% survivors) when administered orally. Three are moderately active: p-aminobenzonitrile (10, 55%), 5-methoxytryptamine octanoic amide (11, 50%), and p-aminobenzophenone (12, 48%).

Influence of elevated temperature on natural killer cell activity, lymphokine-activated killer cell activity and lectin-dependent cytotoxicity of human umbilical cord blood and adult blood cells

PURPOSE

To determine whether hyperthermia is to the benefit or detriment of host immune function, the effect of hyperthermia was evaluated on various functions of T-lymphocytes from human umbilical cord blood and compared to that of adult blood.

METHODS AND MATERIALS

Nonadherent mononuclear cells from cord blood or adult blood were used as the effector cells. To generate lymphokine activated killer (LAK) cells, effector cells were kept in culture for 5 days in complete medium containing recombinant human interleukin-2. To activate effector cells to become cytotoxic, cells were kept in culture in complete medium containing Con A. Cytotoxicity was determined in a standard 4-h chromium release assay using K-562 human erythroleukemic cells (in the natural killer cell activity assay) or Daudi cells (in the LAK cell activity or Lectin dependent cytotoxicity assay) as targets. For heat effects, cells in complete medium were heated at the desired temperature in a water bath for 1 h.

RESULTS

Lymphokine-activated killer cell activity, lectin-dependent cytotoxicity and T-cell proliferative capacity were not deficient in human cord blood. Cytotoxic activities of T-cells from adult blood as well as from cord blood can be enhanced at febrile range (< or = 40 degrees C), and were significantly decreased by exposure to 1 h at 42 degrees C.

CONCLUSION

The febrile responses (< or = 40 degrees C) to infection, in the course of malignant disease and with biological response modifiers treatment, may all be related to host defense mechanisms. Based on these observations, whole body hyperthermia (< or = 40 degrees C), in combination with the appropriate cytokines, may have therapeutic potential in the treatment of neonatal infections and malignancies under certain circumstances. Hyperthermia in febrile range may, therefore, confer an important immunoregulatory advantage to the host. In contrast, tumor killing therapeutic temperature (> 42 degrees C) which inhibits host immunocompetence should probably be used only for local hyperthermia.

Whole-body hyperthermia combined with hyperfractionated irradiation of the thorax in dog: acute physiological response

Whole-body hyperthermia has potential as an adjuvant treatment with chemotherapy and radiation therapy for diseases such as lung cancer which require both local and systemic control. The acute toxicity of whole-body hyperthermia combined with whole-thorax irradiation was studied in dogs. Twenty-eight dogs received three 2-h whole-body hyperthermia (WBH) treatments at 42.0 degrees C deep rectal temperature. Twenty-four of these dogs were also randomized to receive radiation doses of 18, 22.5, 27, 31.5, 40.5 or 45 Gy. Irradiation was given in 1.5 Gy fractions over 6 weeks. Three WBH treatments were given to 28 dogs with all dogs surviving treatment. WBH was given on days 1, 22 and 40 of the 6-week interval. Thirty-one dogs received radiation doses of 18-49.5 Gy without WBH. Deep rectal temperature was maintained at 41.9 +/- 0.3 degrees C over 2 h with an average of 20 min outside the chamber for irradiation. Two dogs required intervention with emergency medications during WBH treatment. One of the two dogs developed permanent neurological injury. Continuous physiological monitoring was necessary for successful WBH. WBH plus thoracic irradiation was well tolerated. All dogs survived all treatments. A significant but transient increase in peripheral blood leucocytes and a decrease in platelet counts occurred after each WBH treatment. The addition of thoracic irradiation up to 45 Gy in 1.5 Gy fractions did not appear to alter the acute toxicity of WBH with the exception of an increase in the protein content of lung lavage fluids. In conclusion, multiple WBH treatments of 2 h at a target temperature of 42 degrees C in addition to thoracic irradiation up to 45 Gy in 1.5 Gy fractions was administered with only mild acute toxicities occurring. Core temperature could be maintained for up to 20 min outside of the WBH chamber which allowed irradiation to be given concurrently with hyperthermia at a core temperature of 42 degrees C +/- 0.1 degree C.

A reliable method for quantitating chromatin fragments by flow cytometry to predict the effect of total body irradiation and hyperthermia on mice

The frequencies of chromatin fragments, including micronuclei, in murine thymus cells, spleen cells and bone marrow cells have been used as a quantitative indicator of gamma-ray induced chromosome damage and could be used to screen potential radioprotective agents as well. The yield of chromatin fragments induced in mice receiving different dosage levels of total body irradiation alone and in mice also given whole body hyperthermia as a potent radioprotector were assessed by flow cytometric analysis. Our results demonstrated that chromatin fragments induced by irradiation in vivo was clearly dose-dependent and that chromatin fragments could potentially serve as a biological indicator of radiation damage. One hour of whole body hyperthermia at 40 degrees C (+/- 0.2 degree C) given 20 hours before a lethal dosage (900 cGy) of total body irradiation protects 100% of DBA/2 mice from an LD 100/16 irradiation dose (dose of irradiation that killed 100% of the mice in 16 days). This is in good agreement with the percent of chromatin fragments formed in the cells of the protected animals, which showed no significant difference from those observed in the normal mice. The results indicate that whole body hyperthermia protected the thymus and bone marrow from irradiation damage. This study provides further evidence which supports that whole body hyperthermia can act as a potent radioprotector in vivo. Measurement of the frequencies of chromatin fragments by flow cytometry is simple and reliable. The method can be applied to screen radioprotective agents.