TDP-43 pathology in multiple system atrophy: colocalization of TDP-43 and α-synuclein in glial cytoplasmic inclusions.

AIMS: This study aimed to assess clinicopathologic features of transactive response DNA-binding protein of 43 kDa (TDP-43) pathology and its risk factors in multiple system atrophy (MSA). METHODS: Paraffin-embedded sections of the amygdala and basal forebrain from 186 autopsy-confirmed MSA cases were screened with immunohistochemistry for phospho-TDP-43. In cases having TDP-43 pathology, additional brain regions were assessed. Immunohistochemical and immunofluorescence double-staining and immunogold electron microscopy (IEM) were performed to evaluate colocalization of TDP-43 and α-synuclein. Genetic risk factors for TDP-43 pathology were also analysed. RESULTS: Immunohistochemistry showed various morphologies of TDP-43 pathology in 13 cases (7%), such as subpial astrocytic inclusions, neuronal inclusions, dystrophic neurites, perivascular inclusions and glial cytoplasmic inclusions (GCIs). Multivariable logistic regression models revealed that only advanced age, but not concurrent Alzheimer's disease, argyrophilic grain disease or hippocampal sclerosis, was an independent risk factor for TDP-43 pathology in MSA (OR: 1.11, 95% CI: 1.04-1.19, P = 0.002). TDP-43 pathology was restricted to the amygdala in eight cases and extended to the hippocampus in two cases. The remaining three cases had widespread TDP-43 pathology. Immunohistochemical and immunofluorescence double-staining and IEM revealed colocalization of α-synuclein and TDP-43 in GCIs with granule-coated filaments. Pilot genetic studies failed to show associations between risk variants of TMEM106B or GRN and TDP-43 pathology. CONCLUSIONS: TDP-43 pathology is rare in MSA and occurs mainly in the medial temporal lobe. Advanced age is a risk factor for TDP-43 pathology in MSA. Colocalization of TDP-43 and α-synuclein in GCIs suggests possible direct interaction between the two molecules.

Influence of exercise training with thigh compression on heat-loss responses.

We investigated the effect of thigh compression, which accelerates activation of central command and muscle metabo- and mechanoreceptors, on the adaptation of sweating and cutaneous vascular responses during exercise heat acclimation. Nine non-heat-acclimated male subjects were acclimated to heat (32 °C and 50% RH) while cycling [50% of maximum oxygen uptake ( V ˙ O 2 m a x )] 60 min/day for 7 days (control group). The experimental group (n = 9) conducted the same training while the proximal thighs were compressed by a cuff at 60 mmHg. V ˙ O 2 m a x , acetylcholine-induced forearm sweating rate (iontophoresis), and mean sweating and cutaneous vascular responses on the forehead, chest, and forearm (SRmean and CVCmean ) during passive heating were evaluated before and after training. Training significantly increased V ˙ O 2 m a x while did not affect acetylcholine-induced sweating rates in either group. Training significantly decreased Tb thresholds for SRmean and CVCmean during passive heating without the alternations of sensitivities in both groups. Although SRmean during passive heating at a given ΔTb was not improved in either group, CVCmean was significantly (P < 0.05) attenuated after exercise training only in experimental group. Our results indicate that thigh cuff compression during exercise heat acclimation does not influence adaptation of the sweating response but attenuate cutaneous vasodilation.

Increasing temperature speeds intracellular PO2 kinetics during contractions in single Xenopus skeletal muscle fibers.

Precise determination of the effect of muscle temperature (T(m)) on mitochondrial oxygen consumption kinetics has proven difficult in humans, in part due to the complexities in controlling for T(m)-related variations in blood flow, fiber recruitment, muscle metabolism, and contractile properties. To address this issue, intracellular Po(2) (P(i)(O(2))) was measured continuously by phosphorescence quenching following the onset of contractions in single Xenopus myofibers (n = 24) while controlling extracellular temperature. Fibers were subjected to two identical contraction bouts, in random order, at 15°C (cold, C) and 20°C (normal, N; n = 12), or at N and 25°C (hot, H; n = 12). Contractile properties were determined for every contraction. The time delay of the P(i)(O(2)) response was significantly greater in C (59 ± 35 s) compared with N (35 ± 26 s, P = 0.01) and H (27 ± 14 s, P = 0.01). The time constant for the decline in P(i)(O(2)) was significantly greater in C (89 ± 34 s) compared with N (52 ± 15 s; P < 0.01) and H (37 ± 10 s; P < 0.01). There was a linear relationship between the rate constant for P(i)(O(2)) kinetics and T(m) (r = 0.322, P = 0.03). Estimated ATP turnover was significantly greater in H than in C (P < 0.01), but this increased energy requirement alone with increased T(m) could not account for the differences observed in P(i)(O(2)) kinetics among conditions. These results demonstrate that P(i)(O(2)) kinetics in single contracting myofibers are dependent on T(m), likely caused by temperature-induced differences in metabolic demand and by temperature-dependent processes underlying mitochondrial activation at the start of muscle contractions.

Identification and characterization of novel multiple bacteriocins produced by Lactobacillus sakei D98.

AIM: To characterize novel multiple bacteriocins produced by Lactobacillus sakei D98. METHODS AND RESULTS: Lactobacillus sakei D98 isolated from Shubo (rice malt) produced at least three bacteriocins. Using three purification steps, three novel antimicrobial peptides termed sakacin D98a, sakacin D98b and sakacin D98c were purified from the culture supernatant. Amino acid and DNA sequencing analysis revealed that the sakacins D98a, D98b and D98c are novel class IIa-like or class IId bacteriocins. In particular, sakacin D98b has a variant pediocin-box sequence, YANGVXC (with Ala instead of Gly), and a different location for the disulfide bridge (Cys(11) and Cys(18)) from that found in other class IIa bacteriocins. CONCLUSIONS: Three novel bacteriocins were identified from Lactobacillus sakei D98. Their antimicrobial spectra and intensities indicate that these sakacins would have different modes of action. In addition, sakacin D98b showed low inhibitory activity against Listeria, probably due to the differences in amino acids and position of the disulfide bridge compared with the other class IIa bacteriocins. SIGNIFICANCE AND IMPACT OF STUDY: Sakacins D98a and D98c are novel bacteriocins belonging to class IId bacteriocins. On the other hand, sakacin D98b, a class IIa-like bacteriocin, has a unique internal structure and activity spectrum.

Usefulness of an artificial neural network for a beginner to achieve similar interpretations to an expert when examining myocardial perfusion images.

This study examined whether using an artificial neural network (ANN) helps beginners in diagnostic cardiac imaging to achieve similar results to experts when interpreting stress myocardial perfusion imaging (MPI). One hundred and thirty-eight patients underwent stress MPI with Tc-labeled agents. An expert and a beginner interpreted stress/rest MPI with or without the ANN and the results were compared. The myocardium was divided into 5 regions (the apex; septum; anterior; lateral, and inferior regions), and the defect score of myocardial blood flow was evaluated from 0 to 4, and SSS, SRS, and SDS were calculated. The ANN effect, defined as the difference in each of these scores between with and without the ANN, was calculated to investigate the influence of ANN on the interpreters' performance. We classified 2 groups (insignificant perfusion group and significant perfusion group) and compared them. In the same way, classified 2 groups (insignificant ischemia group and significant ischemia group) and compared them. Besides, we classified 2 groups (normal vessels group and multi-vessels group) and compared them. The ANN effect was smaller for the expert than for the beginner. Besides, the ANN effect for insignificant perfusion group, insignificant ischemia group and multi-vessels group were smaller for the expert than for the beginner. On the other hand, the ANN effect for significant perfusion group, significant ischemia group and normal vessels group were no significant. When interpreting MPI, beginners may achieve similar results to experts by using an ANN. Thus, interpreting MPI with ANN may be useful for beginners. Furthermore, when beginners interpret insignificant perfusion group, insignificant ischemia group and multi-vessel group, beginners may achieve similar results to experts by using an ANN.

Induction of lymphokine-activated killer-like cells by cancer chemotherapy.

Natural cell-mediated cytotoxicity against NK-resistant target tumor cells was found in the peripheral blood of tumor-bearing patients approximately 1 mo after combined chemotherapy. The recognition specificity of these effector cells was broad and had no restriction. From the experiments of negative selection with mAbs and complements, these newly developed killer cells after chemotherapy were thought to be LAK-like cells. Contribution of these LAK-like cells to the mechanism of action of anticancer drugs remains to be clarified.

[Significance of preoperative ultrasound evaluation of the forearm arteries prior to coronary artery bypass grafting].

We report the significance of preoperative ultrasound evaluation of the forearm arteries in coronary artery bypass grafting (CABG). Ultrasound evaluation was performed in 288 arms with negative Allen's test between August 2004 and July 2007. The diameter, the level of atherosclerotic changes and calcifications, and systolic velocities were evaluated in radial artery (RA) and ulnar artery (UA). The diameter of RA was 2.6 +/- 0.5 mm, and in 30 arms it was smaller than 2 mm. There were 2 occlusions, 4 stenoses, and 20 arteriosclerotic changes in RA. There were 1 occlusion, 8 stenoses, and 4 arteriosclerotic changes in UA. Since there were some overlaps in small diameter and poor qualities of RA and UA, 55 arms (19%) were considered not to qualify as candidates for RA harvest. Pre-operative ultrasound evaluation of the forearm arteries allows safer radial artery harvest and should be performed even in patients with negative Allen' s test.

Significance of Tei-index alterations induced by acute preload reduction with hemodialysis.

AIM: The load dependence of Tei-index, an index to estimate combined systolic and diastolic ventricular functions, remains controversial. Moreover, its significance in the setting of acute preload reduction including hemodialysis (HD) remains unknown. Therefore, we examined the significance of the Tei-index in HD patients. PATIENTS AND METHODS: Doppler echocardiographic parameters of 42 patients with normal left ventricular ejection fraction (LVEF) were evaluated before and after HD. Based on the index of body water excess calculated using a Crit-Line monitor, the patients were assigned to Group A (normal hydration approximately overhydration) and Group B (risk of pulmonary congestion). RESULTS: Group A was younger and had a shorter isovolumic relaxation time (IRT) than Group B before HD. Hemodialysis significantly increased the Tei-index of Group A, which was derived from prolonging IRT and isovolumic contraction time and shortening the ejection time without changing LVEF. Changes in the Tei-index (DeltaTei-index) significantly correlated with the rate at which blood volume decreased. They were derived from graphs generated using the Crit-Line monitor. Furthermore, the DeltaTei-index inversely correlated with the Tei-index before HD. CONCLUSION: These findings suggest that the Tei-index is preload-dependent, which is related to changes in volume and speed. Thus, the Tei-index should be cautiously interpreted according to various hemodynamic situations. However, the correlation between the DeltaTei-index and the Tei-index before HD implies that the latter could be a good indicator of effective fluid removal by HD.

Cardiac preservation is enhanced in a heterotopic rat transplant model by supplementing the nitric oxide pathway.

Nitric oxide (NO) is a novel biologic messenger with diverse effects but its role in organ transplantation remains poorly understood. Using a porphyrinic microsensor, the first direct measurements of coronary vascular and endocardial NO production were made. NO was measured directly in the effluent of preserved, heterotopically transplanted rat hearts stimulated with L-arginine and bradykinin; NO concentrations fell from 2.1 +/- 0.4 microM for freshly explanted hearts to 0.7 +/- 0.2 and 0.2 +/- 0.08 microM for hearts preserved for 19 and 38 h, respectively. NO levels were increased by SOD, suggesting a role for superoxide-mediated destruction of NO. Consistent with these data, addition of the NO donor nitroglycerin (NTG) to a balanced salt preservation solution enhanced graft survival in a time- and dose-dependent manner, with 92% of hearts supplemented with NTG surviving 12 h of preservation versus only 17% in its absence. NTG similarly enhanced preservation of hearts stored in University of Wisconsin solution, the clinical standard for preservation. Other stimulators of the NO pathway, including nitroprusside, L-arginine, or 8-bromoguanosine 3',5' monophosphate, also enhanced graft survival, whereas the competitive NO synthase antagonist NG-monomethyl-L-arginine was associated with poor preservation. Likely mechanisms whereby supplementation of the NO pathway enhanced preservation included increased blood flow to the reperfused graft and decreased graft leukostasis. NO was also measured in endothelial cells subjected to hypoxia/reoxygenation and detected based on its ability to inhibit thrombin-mediated platelet aggregation and serotonin release. NO became undetectable in endothelial cells exposed to hypoxia followed by reoxygenation and was restored to normoxic levels on addition of SOD. These studies suggest that the NO pathway fails during preservation/transplantation because of formation of oxygen free radicals during reperfusion, which quench available NO. Augmentation of NO/cGMP-dependent mechanisms enhances vascular function after ischemia and reperfusion and provides a new strategy for transplantation of vascular organs.

Synthesis and release of interleukin 1 by reoxygenated human mononuclear phagocytes.

To examine the possible involvement of cytokines in reperfusion injury, we have studied production of IL-1 by human vascular cells, including smooth muscle and mononuclear phagocytes. Exposure of cells to hypoxia (pO2 approximately 14 torr) followed by reoxygenation led to significant release of IL-1 only from the mononuclear phagocytes. Elaboration of IL-1 was dependent on the oxygen tension and duration of hypoxia (optimal at lower pO2s, approximately 14-20 torr, and after 9 h), as well as the time in reoxygenation (maximal IL-1 release at 6-9 h). Although a period of hypoxia was necessary for subsequent IL-1 production during reoxygenation of either peripheral blood monocytes or cultured monocyte-derived macrophages, no IL-1 release occurred during the hypoxic exposure. IL-1 released during reoxygenation was newly synthesized, and its production was triggered by the generation of oxygen free radicals, as it could be blocked by the addition of either allopurinol or free radical scavengers to cultures and could be stimulated in part by low concentrations of hydrogen peroxide or xanthine/xanthine oxidase. The potential pathophysiological effects of IL-1-containing supernatants from reoxygenated macrophages was shown by their induction of endothelial tissue factor and enhancement of endothelial adhesiveness for neutrophils, both of which could be blocked by anti-IL-1 antibody. The relevance of IL-1 to hypoxia/reoxygenation in vivo was suggested by the presence of circulating nanogram amounts of this cytokine in the plasma of mice during the reoxygenation period following a hypoxia.

Hypoxia-mediated induction of endothelial cell interleukin-1 alpha. An autocrine mechanism promoting expression of leukocyte adhesion molecules on the vessel surface.

Tissue injury that accompanies hypoxemia/reoxygenation shares features with the host response in inflammation, suggesting that cytokines, such as IL-1, may act as mediators in this setting. Human endothelial cells (ECs) subjected to hypoxia (PO2 approximately 12-14 Torr) elaborated IL-1 activity into conditioned media in a time-dependent manner; this activity was completely neutralized by an antibody to IL-1 alpha. Production of IL-1 activity by hypoxic ECs was associated with an increase in the level of mRNA for IL-1 alpha, and was followed by induction of endothelial-leukocyte adhesion molecule-1 and enhanced expression of intercellular adhesion molecule-1 (ICAM-1) during reoxygenation. During reoxygenation there was a three- to five-fold increased adherence of leukocytes, partly blocked by antibodies to endothelial-leukocyte adhesion molecule-1 and ICAM-1. Suppressing endothelial-derived IL-1, using either antibodies to IL-1 alpha, specific antisense oligonucleotides or the IL-1 receptor antagonist, decreased leukocyte adherence to reoxygenated ECs, emphasizing the integral role of IL-1 in the adherence phenomenon. Mice subjected to hypoxia (PO2 approximately 30-40 Torr) displayed increased plasma levels of IL-1 alpha, induction of IL-1 alpha mRNA in the lung, and enhanced expression of ICAM-1 in pulmonary tissue compared with normoxic controls. These data suggest that hypoxia is a stimulus which induces EC synthesis and release of IL-1 alpha, resulting in an autocrine enhancement in the expression of adhesion molecules.

Development of a voxel phantom of Japanese adult male in upright posture.

A Japanese voxel phantom in upright posture, JM2, has been developed on the basis of CT images of a healthy Japanese adult male. Body characteristics of JM2 were compared with those of the supine voxel phantom, JM, previously developed using CT images of the same person. Differences were found in the shapes of the spine and lower abdomen and the locations of several organs such as kidneys, liver and stomach between the two phantoms. Specific absorbed fractions (SAFs) for 24 target and 11 sources organs were calculated for monoenergetic photon ranging from 0.01 to 4 MeV. It was found that the SAFs for the kidneys as source organ and the lower large intestine wall as target organ in JM2 were significantly higher than those in JM for all photon energies. The differences of the SAFs between the two phantoms were attributed to the differences in the organ distance and organ geometry depending on the posture.

Japanese adult male voxel phantom constructed on the basis of CT images.

A Japanese adult male voxel (volume pixel) phantom (hereinafter referred to as the JM phantom) was constructed on the basis of CT images of a healthy Japanese adult male volunteer. Body characteristics of the JM phantom were compared with those of a voxelised MIRD5 type phantom and a Japanese adult male voxel phantom which was previously developed. The voxel size of the JM phantom is 0.98 x 0.98 x 1 mm(3). The shapes of the organs of the JM phantom, even for small or complicated organs, such as thyroid and stomach, are more realistically reproduced as compared with the previous Japanese voxel phantom (voxel size: 0.98 x 0.98 x 10 mm(3)). Photon self-absorbed fractions (self-AFs) for brain, kidneys, spleen, pancreas, thyroid and urinary bladder wall of JM were evaluated and were compared with those of the other phantoms. In consequence, it was suggested that the mass, shape and thickness of organs are important factors for the determination of self-AFs.

[Minimally invasive technique for harvesting a saphenous vein via one small incision].

We report a minimally invasive technique for harvesting a saphenous vein graft (SVG) via 1 small skin incision. The expected advantages of this technique are better cosmetic results and fewer wound complications than the conventional open technique or the bridging technique. The SVG, 10-15 cm in length, can be harvested by about 3 cm-long single small skin incision. SaphLITE Retractor System (Genzyme Srugical Products, Cambridge), SLS Hematostatic Clip System (Vitalitec International, Plymouth), and curved scissors were necessary instruments for this technique. It is feasible for cases that require a shorter length of SVG.

Structural basis for the ADP-specificity of a novel glucokinase from a hyperthermophilic archaeon.

BACKGROUND: ATP is the most common phosphoryl group donor for kinases. However, certain hyperthermophilic archaea such as Thermococcus litoralis and Pyrococcus furiosus utilize unusual ADP-dependent glucokinases and phosphofructokinases in their glycolytic pathways. These ADP-dependent kinases are homologous to each other but show no sequence similarity to any of the hitherto known ATP-dependent enzymes. RESULTS: We solved the crystal structure at 2.3 A resolution of an ADP-dependent glucokinase from T. litoralis (tlGK) complexed with ADP. The overall structure can be divided into large and small alpha/beta domains, and the ADP molecule is buried in a shallow pocket in the large domain. Unexpectedly, the structure was similar to those of two ATP-dependent kinases, ribokinase and adenosine kinase. Comparison based on three-dimensional structure revealed that several motifs important both in structure and function are conserved, and the recognition of the alpha- and beta-phosphate of the ADP in the tlGK was almost identical with the recognition of the beta- and gamma-phosphate of ATP in these ATP-dependent kinases. CONCLUSIONS: Noticeable points of our study are the first structure of ADP-dependent kinase, the structural similarity to members of the ATP-dependent ribokinase family, its rare nucleotide specificity caused by a shift in nucleotide binding position by one phosphate unit, and identification of the residues that discriminate ADP- and ATP-dependence. The strict conservation of the binding site for the terminal and adjacent phosphate moieties suggests a common ancestral origin of both the ATP- and ADP-dependent kinases.

Enhanced induction by high-cholesterol diet of remnant gastric carcinogenesis by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

The influence of bile acids on the development of remnant gastric carcinoma was examined by investigating the incidence of carcinogenesis in noninbred male Wistar rats treated orally with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG; CAS 70-25-7; 1-methyl-3-nitro-1-nitrosoguanidine) and fed a diet containing 1% cholesterol. The high-cholesterol diet did not influence the incidence of carcinoma in the nongastrectomized, MNNG-treated groups of rats. However, in the gastrectomized groups, the incidence of carcinoma was significantly higher in the group given the high-cholesterol diet (60.6%) than in the group given a normal diet (35.5%). Histologically undifferentiated adenocarcinoma was recognized more frequently in the high-cholesterol-diet group. Three gastrectomized rats not treated with MNNG but fed the high-cholesterol diet developed remnant gastric carcinoma (13%), whereas none of the rats given the normal diet did. Because the fecal excretion of bile acids increased significantly in the rats fed the high-cholesterol diet and the gastroduodenal reflux of bile acids was probably accelerated, the increase in the incidence of carcinogenesis in the remnant stomach was considered to be the result of the increase in the reflux of bile acids evoked by a high-cholesterol diet.

Possible role of duodenogastric reflux on the development of remnant gastric carcinoma induced by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

The relationship between operative procedures and the incidence of remnant stomach carcinoma was investigated in male Wistar rats orally treated with N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) CAS: 70-25-7; 1-methyl-3-nitro-1-nitrosoguanidine]. A total of 178 rats was divided into 5 groups: After gastrectomy in which half of the glandular stomach was removed, group 1 received Billroth II reconstruction; group 2 was given short Roux-en-Y reconstruction; group 3 had long Roux-en-Y reconstruction; group 4 received gastrotomy alone; and group 5 consisted of nonoperated control rats. The incidence of gastric adenocarcinoma in MNNG-treated rats was significantly higher in group 1 (38.9%) as compared with that in group 3 (7.1%) and that in group 5 (9.5%). All tumors developed in the gastroenteric anastomotic area. Histologic examination of the gastric mucosa revealed atrophic gastritis and erosion in the gastroenteric anastomotic area, especially in rats with carcinoma. These findings seem to implicate the duodenogastric reflux, especially the reflux of bile acids, in the development of remnant stomach carcinoma in rats.

Effects of total-body hyperthermia on metastases from experimental mouse tumors.

To study the effects of total-body hyperthermia (TBH) on metastases from malignant tumors, Lewis lung carcinoma (LLC)-bearing C57BL/6 mice and mouse ascites hepatoma 134-bearing C3H/He mice were immersed in a heated water bath. Rectal temperature was maintained for 30 min at 40 degrees C or 42 degrees C. After treatment, the incidence of lung metastasis was analyzed in LLC-inoculated mice, and the presence or absence of metastasis in affiliated lymph nodes was determined in mouse ascites hepatoma 134-inoculated mice. A significant inhibition in primary tumor growth in LLC- and mouse ascites hepatoma 134-bearing mice treated with 42 degrees C TBH was noted. The incidence of lung metastasis was increased from the control level of 1.6 +/- 0.63 (SD) to 2.4 +/- 0.98 in the 42 degrees C TBH (P less than 0.01) groups but not in the 40 degrees C TBH group. Metastasis to affiliated lymph nodes was similar for the controls and the 40 degrees C and 42 degrees C TBH groups. The increase in lung metastasis in LLC-treated mice subjected to 42 degrees C TBH could be prevented by the combined use of anticancer drugs such as cis-diamminedichloroplatinum(II) (1.0, 3.0 mg/kg) or mitomycin C (0.3, 1.0 mg/kg). Furthermore, the combined use of 42 degrees C TBH and anticancer drugs showed the inhibition of primary tumor growth to a greater degree than did 42 degrees C TBH alone or anticancer drugs alone. Since 42 degrees C TBH may induce tumor metastasis, especially hematogenous metastasis, it seems advisable to use anticancer drugs in combination with clinical thermal applications.

Morphogenesis of peritoneal metastasis in human gastric cancer.

A comparative light microscopic and scanning electron microscopic study of the morphogenesis of peritoneal metastasis in 34 human gastric cancers was performed. Prior to adhesion of gastric cancer cells to the peritoneum, the mesothelial cells became hemispherical and exfoliated from the peritoneum, and gastric cancer cells adhered to the naked areas of the submesothelial connective tissue. A flat metastatic tumor was formed by cancer cell proliferation in the shallow region of the peritoneum. Subsequently, after the infiltration of cancer cells into the connective and adipose tissue, the formation of a large tumor mass was observed. There was a correlation between the surface and histological structure of the metastatic tumors. In poorly differentiated cancer, the cells were isolated while in differentiated cancer, they formed nodules with indistinguishable cell boundaries.

Mechanism of metastatic spread by 42 degrees C total-body hyperthermia in Lewis lung carcinoma.

We investigated the mechanism of metastatic spread in Lewis lung carcinoma-bearing C57BL/6 mice exposed to 42 degrees C total-body hyperthermia (TBH) by water immersion. When the mice were treated with 42 degrees C TBH 24 h after resection of the primary tumor, the spread of lung metastasis was inhibited (P less than 0.01). When tumor-bearing mice were exposed to 42 degrees C TBH followed by resection of the primary tumors 24 h later, the spread of lung metastasis was greater than in the control group from which tumors were removed 6 days after inoculation (P less than 0.05). When normal mice were subjected to 42 degrees C TBH and Lewis lung carcinoma cells were subsequently injected i.v., lung metastasis increased significantly in those mice that had received tumor cell injection between immediately after and 48 h after TBH treatment (P less than 0.02-0.001). Tumor-bearing mice were subjected to 42 degrees C TBH, and changes in the lung tissues were examined. Between 12 and 48 h after TBH, alveolar collapse, edema, and cellular infiltration into the alveolar walls were seen. Tumor-bearing mice were exposed to 42 degrees C TBH and blood was taken from the inferior vena cava. The number of tumor cells in the blood increased significantly 12 h after TBH exposure (P less than 0.05). We suggest that TBH promotes the intravascular invasion of tumor cells and that histological changes in the host lung facilitate the implantation of tumor cells.