[Report of incidence and mortality of gallbladder cancer in China, 2014].

Objective: The incidence and mortality of gallbladder cancer from Chinese cancer registries in 2014 were analyzed to describe the prevalence of gallbladder cancer in China. Methods: Incidence and mortality data of gallbladder cancer in 2014 derived from registration data in 2017, collected by the National Central Cancer Registry (NCCR). Qualified data from 339 cancer registries were calculated after evaluating. According to the national population data of 2014, the gallbladder cancer incidence and mortality of China in 2014 were stratified by the area, gender and age.The age composition of standard population of Chinese census in 2000 and Segi's population were used for age-standardizes incidence and mortality in China and worldwide. Results: 339 cancer registries cover a total of 288 243 347 population including 146 203 891 males and 142 039 456 females (144 061 915 in urban and 144 181 432 in rural areas). The mortality to incidence ratio of gallbladder cancer was 0.74. The morphologically verified cases (MV%) and death certificate-only cases (DCO%) were 48.38% and 2.66%, respectively. Unclear diagnosis cases (UB%) was 0.48%. The crude incidence of gallbladder cancer in China in 2014 was 3.82/100 000, which accounted for 1.37% of new cancer cases (4.48/100 000 in urban areas and 3.01/100 000 in rural areas, 3.59/100 000 for male and 4.05/100 000 for female). Age-standardized incidence rates by Chinese standard population (ASR China) and world standard population (ASR world) were 2.38/100 000 and 2.37/100 000, respectively, and the cumulative incidence rate (0-74 age years old) was 0.27%.Besides, the crude mortality of gallbladder cancer was 2.86/100 000 (3.47/100 000 in urban areas and 2.12/100 000 in rural areas, 2.59/100 000 for male and 3.14/100 000 for female). Age-standardized mortality rates by ASR China and ASR world were 1.72/100 000 and 1.71/100 000, with a cumulative mortality rate (0-74 age years old) of 0.19%. Conclusion: The incidence and mortality of gallbladder cancer were significantly different between the city and country, while not obviously different between the female and male.

The intrapapillary capillary loop (IPCL) changes in superficial esophageal lesions.

The aims of this study were to investigate intrapapillary capillary loops (IPCLs) of superficial esophageal lesions changes in different types classified by the Japan Esophageal Society classification. The calibers, areas, and densities of IPCLs were detected in 34 cases of esophageal lesions using immunohistochemical analysis. Statistically significant differences in calibers, areas, and densities of IPCLs were observed between type A, type B1/B2, and type B3 area (P < 0.001). In conclusion, the results of this observation showed the Japan Esophageal Society classification of IPCL would help endoscopists to diagnose the type and the invasion depth of lesion in esophagus, and decide the treatment strategy.

[Validity, reliability, and acceptability of the brief version of the self-management knowledge, attitude, and behavior assessment scale for diabetes patients].

OBJECTIVE: To evaluate the validity, reliability, and acceptability of the brief version of the self-management knowledge, attitude, and behavior (KAB) assessment scale for diabetes patients. METHODS: Diabetes patients who were managed at the Xinkaipu Community Health Service Center of Tianxin in Changsha, Hunan Province were selected for survey by cluster sampling. A total of 350 diabetes patients were surveyed using the brief scale to collect data on knowledge, attitudes, and behaviors of self-management. Content validity was evaluated by Pearson correlation coefficient between the brief scale and subscales of knowledge, attitude, and behavior. Structure validity was evaluated by factor analysis, and discrimination validity was evaluated by an independent sample t-test between the high-score and low-score groups. Reliability was tested by internal consistency reliability and split-half reliability. The evaluation indexes of internal consistency reliability were Cronbach's α coefficients, θ coefficient, and Ω coefficient. Acceptability was evaluated by valid response rate and completion time of the brief scale. RESULTS: A total of 346(98.9%) valid questionnaires were returned, with average survey time of (11.43±3.4) minutes. Average score of the brief scale was 78.85 ± 11.22; scores of the knowledge, attitude, and behavior subscales were 16.45 ± 4.42, 21.33 ± 2.03, and 41.07 ± 8.34, respectively. Pearson correlation coefficients between the brief scale and the knowledge, attitude, and behavior subscales were 0.92, 0.42, and 0.60, respectively; P-values were all less than 0.01, indicating that the face validity and content validity of the brief scale were achieved to a good level. The common factor cumulative variance contribution rate of the brief scale and three subscales was from 53.66% to 61.75%, which achieved more than 50% of the approved standard. There were 11 common factors; 41 of the total 42 items had factor loadings above 0.40 in their relevant common factor, indicating that the brief scale and three subscales had good construct validity. Patients were divided into a high-score group and a low-score group, then scores of the brief scale and three subscales were compared between the groups using a t-test. The results were all significant, indicating that the brief scale and three subscales had good discriminate validity. Mean scores of the brief scale and three subscales of the high-score group were 91.55±6.81, 19.51±2.17, 22.74±1.88, and 49.30±6.20, respectively; these were higher than the low-score group (65.89±5.79, 12.29±4.76, 20.22±1.88, and 33.39±6.17, respectively) with t-values 27.76, 13.31, 9.20, and 17.56 (P-values were less than 0.001). The Cronbach's α coefficient, θ coefficient, Ω coefficient, and split-half reliability of the brief scale were 0.83, 0.87, 0.96, and 0.84, respectively. These values for the three subscales were all above 0.70, except for the θ coefficient of the attitude subscale with 0.64, indicating that the brief scale and three subscales had acceptable internal consistency reliability. CONCLUSION: The brief version of the diabetes self-management knowledge, attitude, and behavior assessment scale showed good acceptability, validity, and reliability, to responsibly evaluate self-management KAB among patients with diabetes.

[Meteorological factors and related lag effects on scrub typhus in southwestern Yunnan].

Objective: To analyze the influence and related lag effects of meteorological factors on scrub typhus (ST) in southwestern Yunnan, to provide a reference for the corresponding prevention and treatment measures. Methods: Data on ST and meteorology in Yunnan province from 2007 to 2018 were collected. A distributed lag nonlinear model was conducted to study the cumulative lag effects of temperature, relative humidity, and rainfall on ST. Results: From 2007-2018, a total of 19 975 ST cases were reported in southwestern Yunnan. Weekly mean temperature, mean relative humidity, and the risk of ST all showed J-shaped curves. The cumulative risk of ST increased with mean temperature >23 ℃, mean relative humidity >80%, and cumulative rainfall between 20 and 60 mm or over 100 mm, weekly. Taking the median value as the reference, higher temperature (22.27 ℃, 23.45 ℃), relative humidity (80.14%, 84.38%) and rainfall (37.17 mm, 74.42 mm) all increased the risk of disease while lower temperature (11.22 ℃,14.83 ℃), relative humidity (53.18%,65.36%) and rainfall (0.00 mm,0.55 mm) showed opposite effects. The temperature-lag effect lasted for 10 and 16 weeks, respectively, with ST's risk the highest during the week of exposure. Humidity-lag effects usually last for 10 and 17 weeks. The lag effect of rainfall lasted for 25 weeks, while the disease's risk was the highest in the 4th week. Conclusion: Factors as temperature, relative humidity, and precipitation showed nonlinear and lag effects on ST. High temperature, high relative humidity, and an appropriate amount of rainfalls increase the risk of ST. The authorities of public health should implement effective prevention and control measures according to meteorological conditions.

Ku70 is required for DNA repair but not for T cell antigen receptor gene recombination In vivo.

Ku is a complex of two proteins, Ku70 and Ku80, and functions as a heterodimer to bind DNA double-strand breaks (DSB) and activate DNA-dependent protein kinase. The role of the Ku70 subunit in DNA DSB repair, hypersensitivity to ionizing radiation, and V(D)J recombination was examined in mice that lack Ku70 (Ku70(-/-)). Like Ku80(-/-) mice, Ku70(-/-) mice showed a profound deficiency in DNA DSB repair and were proportional dwarfs. Surprisingly, in contrast to Ku80(-/-) mice in which both T and B lymphocyte development were arrested at an early stage, lack of Ku70 was compatible with T cell receptor gene recombination and the development of mature CD4+CD8- and CD4-CD8+ T cells. Our data shows, for the first time, that Ku70 plays an essential role in DNA DSB repair, but is not required for TCR V(D)J recombination. These results suggest that distinct but overlapping repair pathways may mediate DNA DSB repair and V(D)J recombination.

Systematic review and meta-analysis of randomized controlled trials comparing stapled haemorrhoidopexy with conventional haemorrhoidectomy.

BACKGROUND: This paper compares stapled haemorrhoidopexy with conventional haemorrhoidectomy for the treatment of haemorrhoids. METHODS: An electronic literature search was undertaken to identify primary studies and systematic reviews. Results on efficacy and safety were analysed. A meta-analysis was conducted to examine long-term outcomes. RESULTS: Twenty-nine randomized clinical trials recruiting 2056 patients were identified. Meta-analysis showed that stapled haemorrhoidopexy was less painful than conventional haemorrhoidectomy. Stapled haemorrhoidopexy required a shorter inpatient stay (weighted mean difference (WMD) -0.95 (95 per cent confidence interval (c.i.) -1.32 to -0.59) days; P < 0.001) and operating time (WMD -11.42 (95 per cent c.i. -18.26 to -4.59) min; P = 0.001). It was also associated with a faster return to normal activities (WMD -11.75 (95 per cent c.i. -21.42 to -2.08) days; P = 0.017). No significant difference was noted between the two techniques in terms of the total incidence of complications. Stapled haemorrhoidopexy was associated with a higher rate of recurrent disease (relative risk 2.29 (95 per cent c.i. 1.57 to 3.33); P < 0.001). CONCLUSION: Stapled haemorrhoidopexy offers some short-term benefits over conventional operation but the total complication rates are similar for both techniques. Stapled haemorrhoidopexy is associated with a higher rate of recurrent disease.

Circulating exosomal miRNAs as diagnostic biomarkers in Parkinson's disease.

OBJECTIVE: This research has showed that exosomal miRNAs from cerebrospinal fluid could act as biomarkers for Parkinson's disease (PD). However, no analysis has been conducted to explore the potential value of exosomal miRNAs from plasma. PATIENTS AND METHODS: 52 patients with PD were included in study group. 48 healthy adults were included in control group. Blood samples were collected from all those people and then exosomes were extracted from the plasma. RESULTS: Compared with controls, patients with PD showed a significantly higher expression of circulating exosomal miR-331-5p. ROC curve showed that the area values under the curve of miR-331-5p and miR-505 were 0.849 and 0.898, respectively. CONCLUSIONS: Exosomal miRNAs, including miR-331-5p and miR-505, could potentially act as biomarkers for PD.

Interaction between heat shock factor and hsp70 is insufficient to suppress induction of DNA-binding activity in vivo.

The intracellular level of free heat shock proteins, in particular the 70-kDa stress protein family, has been suggested to be the basis of an autoregulatory mechanism by which the cell measures the level of thermal stress and regulates the synthesis of heat shock proteins. It has been proposed that the DNA-binding and oligomeric state of the heat shock transcription factor (HSF) is a principal step in the induction pathway that is responsive to the level of 70-kDa stress protein. To test this hypothesis, we investigated the association between HSF and 70-kDa stress protein by means of a coimmunoprecipitation assay. We found that 70-kDa stress proteins associate to similar extents with both latent and active forms of HSF, although unlike other 70-kDa stress protein substrates, the association with HSF was not significantly disrupted in the presence of ATP. Gel mobility shift assays indicated that active HSF trimers purified from a bacterial expression system could not be substantially deactivated in vitro with purified 70-kDa stress protein and ATP. In addition, elevated concentrations of hsp70 alone could not significantly inhibit induction of the DNA-binding activity of endogenous HSF in cultured rat cells, and the induction was also not inhibited in cultured rat cells or Drosophila cells containing elevated levels of all members of the heat shock protein family. However, the deactivation of HSF to the non-DNA-binding state after prolonged heat stress or during recovery could be accelerated by increased levels of heat shock proteins. Hence, the level of heat shock proteins may affect the rate of disassembly of HSF trimers, but another mechanism, as yet undefined, appears to control the onset of the oligomeric transitions.

Modulation of thermal induction of hsp70 expression by Ku autoantigen or its individual subunits.

Previously, we proposed a dual control mechanism for the regulation of the heat shock response in mammalian cells: a positive control mediated by the heat shock transcription factor HSF1 and a negative control mediated by the constitutive heat shock element-binding factor (CHBF). To study the physiological role of CHBF in the regulation of heat shock response, we purified CHBF to apparent homogeneity and showed it to be identical to the Ku autoantigen, a heterodimer consisting of 70-kDa (Ku-70) and 86-kDa (Ku-80) polypeptides. To study further the functional significance of Ku/CHBF in the cellular response to heat shock, we established rodent cell lines that stably and constitutively overexpressed one or both subunits of the human Ku protein, and examined the thermal induction of hsp70 and other heat shock proteins in these Ku-overexpressing ing cells. We show that expression of the human Ku-70 and Ku-80 subunits jointly or of the Ku-70 subunit alone specifically inhibits heat-induced hsp70 expression. Conversely, expression of human Ku-80 alone does not have this effect. Thermal induction of other heat shock proteins in all of the Ku-overexpressing cell lines appears not to be significantly affected, nor is the state of phosphorylation or the DNA-binding ability of HSF1 affected. These findings support a model in which hsp70 expression is controlled by a second regulatory factor in addition to the positive activation of HSF1. The Ku protein, specifically the Ku-70 subunit, is involved in the regulation of hsp70 gene expression.

[Significance of bacteria detection with filter paper method on diagnosis of diabetic foot wound infection].

Objective: To evaluate the significance of bacteria detection with filter paper method on diagnosis of diabetic foot wound infection. Methods: Eighteen patients with diabetic foot ulcer conforming to the study criteria were hospitalized in Liyuan Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from July 2014 to July 2015. Diabetic foot ulcer wounds were classified according to the University of Texas diabetic foot classification (hereinafter referred to as Texas grade) system, and general condition of patients with wounds in different Texas grade was compared. Exudate and tissue of wounds were obtained, and filter paper method and biopsy method were adopted to detect the bacteria of wounds of patients respectively. Filter paper method was regarded as the evaluation method, and biopsy method was regarded as the control method. The relevance, difference, and consistency of the detection results of two methods were tested. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of filter paper method in bacteria detection were calculated. Receiver operating characteristic (ROC) curve was drawn based on the specificity and sensitivity of filter paper method in bacteria detection of 18 patients to predict the detection effect of the method. Data were processed with one-way analysis of variance and Fisher's exact test. In patients tested positive for bacteria by biopsy method, the correlation between bacteria number detected by biopsy method and that by filter paper method was analyzed with Pearson correlation analysis. Results: (1) There were no statistically significant differences among patients with wounds in Texas grade 1, 2, and 3 in age, duration of diabetes, duration of wound, wound area, ankle brachial index, glycosylated hemoglobin, fasting blood sugar, blood platelet count, erythrocyte sedimentation rate, C-reactive protein, aspartate aminotransferase, serum creatinine, and urea nitrogen (with F values from 0.029 to 2.916, P values above 0.05), while there were statistically significant differences among patients with wounds in Texas grade 1, 2, and 3 in white blood cell count and alanine aminotransferase (with F values 4.688 and 6.833 respectively, P<0.05 or P<0.01). (2) According to the results of biopsy method, 6 patients were tested negative for bacteria, and 12 patients were tested positive for bacteria, among which 10 patients were with bacterial number above 1×10(5)/g, and 2 patients with bacterial number below 1×10(5)/g. According to the results of filter paper method, 8 patients were tested negative for bacteria, and 10 patients were tested positive for bacteria, among which 7 patients were with bacterial number above 1×10(5)/g, and 3 patients with bacterial number below 1×10(5)/g. There were 7 patients tested positive for bacteria both by biopsy method and filter paper method, 8 patients tested negative for bacteria both by biopsy method and filter paper method, and 3 patients tested positive for bacteria by biopsy method but negative by filter paper method. Patients tested negative for bacteria by biopsy method did not tested positive for bacteria by filter paper method. There was directional association between the detection results of two methods (P=0.004), i. e. if result of biopsy method was positive, result of filter paper method could also be positive. There was no obvious difference in the detection results of two methods (P=0.250). The consistency between the detection results of two methods was ordinary (Kappa=0.68, P=0.002). (3) The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of filter paper method in bacteria detection were 70%, 100%, 1.00, 0.73, and 83.3%, respectively. Total area under ROC curve of bacteria detection by filter paper method in 18 patients was 0.919 (with 95% confidence interval 0-1.000, P=0.030). (4) There were 13 strains of bacteria detected by biopsy method, with 5 strains of Acinetobacter baumannii, 5 strains of Staphylococcus aureus, 1 strain of Pseudomonas aeruginosa, 1 strain of Streptococcus bovis, and 1 strain of bird Enterococcus. There were 11 strains of bacteria detected by filter paper method, with 5 strains of Acinetobacter baumannii, 3 strains of Staphylococcus aureus, 1 strain of Pseudomonas aeruginosa, 1 strain of Streptococcus bovis, and 1 strain of bird Enterococcus. Except for Staphylococcus aureus, the sensitivity and specificity of filter paper method in the detection of the other 4 bacteria were all 100%. The consistency between filter paper method and biopsy method in detecting Acinetobacter baumannii was good (Kappa=1.00, P<0.01), while that in detecting Staphylococcus aureus was ordinary (Kappa=0.68, P<0.05). (5) There was no obvious correlation between the bacteria number of wounds detected by filter paper method and that by biopsy method (r=0.257, P=0.419). There was obvious correlation between the bacteria numbers detected by two methods in wounds with Texas grade 1 and 2 (with r values as 0.999, P values as 0.001). There was no obvious correlation between the bacteria numbers detected by two methods in wounds with Texas grade 3 (r=-0.053, P=0.947). Conclusions: The detection result of filter paper method is in accordance with that of biopsy method in the determination of bacterial infection, and it is of great importance in the diagnosis of local infection of diabetic foot wound.

A preliminary assessment of consumer's exposure to pesticide residues in fisheries products.

The fisheries products in this study comprise fish, bivalve, crustacean and cephalopod collected from different types of markets in Taiwan between the years 2001 and 2003. A total of 91 pesticide residues belonging to four major pesticide groups were tested and analyzed. The test results show that 65.40% of fish, 93.55% of shellfish, 84.92% of crustacean and 98.33% of cephalopod samples contain no detectable residues. There are only two kinds (organochlorine and organophosphate) of totally six pesticides (DDTs, dieldrin, chlorpyrifos, fenitrotion, fenthion and prothion) that have been detected from the fisheries products in this study. For there were pesticides present in the fish products, consumption of fisheries product there was no zero risk. But the exposure of consumer did not exceed the acceptable daily intakes (ADI). For male, there was the highest risk in exposure to dieldrin, which the percentage of ADI was 93.56%. This study also suggests that a yearly monitoring program for organophosphate pesticide residues in fish is necessity.

Thermal biology and physiology in clinical hyperthermia: current status and future needs.

The current status and needs of thermal biology and physiology as related to clinical hyperthermia are summarized. Emphasis is placed on heat-induced modification of blood flow and microenvironment in tissues, on the biological effects of heat and X-rays, and on the relationship between drug resistance, heat resistance, and thermotolerance in thermochemotherapy. Results from recent studies investigating the relationships between thermotolerance and heat shock proteins in tissue culture cell lines, in rodent tumors, and in normal tissues are presented. These data strongly suggest that the levels of Mr 70,000 heat shock protein can be used as an assay to predict the thermal sensitivity of tissues during fractionated hyperthermia.

Lack of effect of thermotolerance on radiation response and thermal radiosensitization of murine bone marrow progenitors.

We studied X-ray response, thermal radiosensitization, and time sequencing between heat and radiation for nontolerant and thermotolerant murine bone marrow cells. Survival curves of colony-forming units of granulocyte-macrophages (CFU-GM) have a D0 value of 1.26 +/- 0.04 Gy when irradiated in vivo. Heating at 44 degrees C for 30 min immediately prior to X-ray yields a D0 value of 0.96 Gy, with a thermal enhancement ratio of 1.3. Similar D0 and thermal enhancement ratio values were seen for thermotolerant cells. In vitro experiments with CFU-GM gave similar results. Studies of the effect of time sequence on heat and radiation indicate that for CFU-GM, the interaction between the two modalities do not fully disappear when given within 180 min of each other. Colony-forming units of erythrocytes (CFU-E) irradiated in vivo shows a D0 value of 1.1 +/- 0.03 Gy for radiation alone. Heating at 44 degrees C for 25 min prior to irradiation gives a D0 value of 0.95 Gy (thermal enhancement ratio, 1.1). Again, there was no change in the D0 value of radiation alone or the combination of heat and radiation in thermotolerant CFU-E. Both radiation killing and thermal radiosensitization were the same for thermotolerant and nontolerant CFU-GM and CFU-E.

Induction of heat shock protein synthesis in murine tumors during the development of thermotolerance.

The function of one or more heat shock proteins (HSPs) may be to confer protection of cells against thermal damage. We examined the induction kinetics of thermotolerance and the synthesis of HSPs in murine tumor models. Squamous cell carcinomas (SCC VII/SF) or radiation-induced fibrosarcomas (RIF) were implanted in the flanks of C3H mice. These flank tumors were first exposed to an elevated temperature (41 degrees-45 degrees C) for a fixed duration, for example, 43 degrees C for 15 min. Some of the tumors were excised immediately, and tumor cell suspensions were made. The other mice with tumors were returned to the cages and left undisturbed for various times up to 72 h before being sacrificed. Again, tumors were then removed and tumor cell suspensions were prepared. These tumor cells were either challenged with a second heat treatment at 45 degrees C in vitro or labeled with [35S]methionine at 37 degrees C in vitro. The tumor cell survival after the combined heat treatments was measured using the in vitro cloning assay. The cellular proteins were analyzed by one- or two-dimensional gel electrophoresis. We found that mild heat shock induced thermotolerance in murine tumors, a result consistent with those of others. The kinetics of induction and decay of thermotolerance depended on the temperature and duration of the priming treatment. Mild heat shock also enhanced the rate of synthesis and accumulation of some HSPs during the development of thermotolerance. For example, after an initial treatment at 43 degrees C for 15 min, the rates of synthesis of HSPs with molecular weights 68,000, 70,000, and 88,000 were greatly enhanced in SCC VII/SF tumors when compared to unheated controls. Qualitatively similar results were seen with radiation-induced fibrosarcoma tumors. The rate of synthesis of Mr 68,000 to 70,000 HSPs reached maximum value (300% of control value) 2 to 4 h after heat shock and decreased to the control value 6 to 24 h later. On the other hand, the rate of synthesis of actin, a major structural cellular protein, remained relatively constant throughout the 72 h of experiments. We then determined the relationship between the synthesis and accumulation of these HSPs and the expression of thermotolerance in murine tumors after a priming heat treatment. The data indicate that the levels of Mr 68,000 to 70,000 HSPs correlate well with thermotolerance.(ABSTRACT TRUNCATED AT 400 WORDS)

Thermotolerance and profile of protein synthesis in murine bone marrow cells after heat shock.

In this study, we first investigated the survival of colony-forming units, granulocyte and macrophage (CFU-GM), after a single heat treatment. We then examined the induction, development, and decay of thermotolerance in CFU-GM. Finally, we analyzed the profiles of protein synthesis in the total murine bone marrow population during the development of thermotolerance. Several salient features emerged from our study: (a) granulocyte-macrophage progenitors were very sensitive to heat as compared to other mammalian cell lines; (b) CFU-GM can develop thermotolerance after both prolonged heating at 41-42 degrees C or an acute heat treatment at 43 degrees C in vitro; (c) thermotolerance in CFU-GM can be induced in vivo; the kinetics of development of thermotolerance in vivo is similar to that in vitro; (d) in contrast to other cell lines where thermotolerance lasts for several days, tolerance acquired by CFU-GM disappeared within 24 h, regardless of the temperature or duration of the initial heat treatment. The difference between the kinetics of systemic thermotolerance and thermotolerance in CFU-GM in the same animal model shows that bone marrow stem cells, or at least CFU-GM, are not the critical targets for systemic thermal death. When protein synthesis profiles of the heat-shocked bone marrow cells were compared to those from nonheated controls by one- and two-dimensional gel electrophoresis, the rates of synthesis of the Mr 70,000 and 87,000 proteins were shown to be enhanced during the development of thermotolerance. The enhanced rate of synthesis of these polypeptides lasted only 2-4 h and then returned to the control value.

A proposed operational model of thermotolerance based on effects of nutrients and the initial treatment temperature.

The phenomenon of thermotolerance in mammalian cells has been extensively documented in the literature. Because of its potential clinical importance as well as the fundamental biological interest, we pursued additional studies investigating pH and nutritional effects. Split-dose experiments were performed using plateau phase Chinese hamster HA-1 cells. The effects of the nutritional environment during the initial 43 degrees incubation and the second 43 degree treatment on the induction of thermotolerance were studied by comparing survival in full medium at pH 7.4 or in Hanks' balanced salt solution at pH 6.7. In additional experiments, we examined the effect on thermotolerance of changing the temperature of the initial treatment to 41 degrees. Thermotolerance was induced independently of the nutrient conditions of the first treatment. However, survival at the time of maximum expression of thermotolerance depended primarily on the duration and temperature of the initial treatment. Temperatures of 43 degrees or higher inhibited the development of thermotolerance during the first heat exposure. In contrast, if the initial exposure was at 41 degrees, thermotolerance was almost fully expressed by the end of this initial treatment. Changing pH in Hanks' balanced salt solution from 6.7 to 7.4 did not affect survival. On the basis of these and other data, we suggest that thermotolerance can be divided into three complementary and sometimes competing processes: an initial event ("trigger"); the expression of resistance ("development"); and its disappearance ("decay"). Trigger is induced at all hyperthermic temperatures while development requires a permissive temperature, i.e., less than 43 degrees for HA-1 cells. This model can provide plausible interpretations of several currently puzzling aspects of the survival kinetics of heat-exposed mammalian cells.

Effect of drug exposure duration and sequencing on hyperthermic potentiation of mitomycin-C and cisplatin.

The effects of drug exposure duration and of heat and drug sequencing on hyperthermic potentiation of mitomycin-C (MMC) and cisplatin (DDP) were studied. Heating for 1 h at 42 degrees C was combined with drug exposure times of 1, 2, 4, or 8 h. For both DDP and MMC, hyperthermic potentiation was greatest when heating was done during drug exposure. Dose enhancement ratios for both drugs at 1% survival were highest with the shortest drug exposure times and decreased as the drug exposure time increased from 1 to 8 h. For DDP, the dose enhancement ratio decreased from 1.9 with a 1-h drug exposure to 1.2 with an 8-h drug exposure. For MMC, the dose enhancement ratio decreased from 1.8 to 1.5 as the drug exposure duration was increased from 1 to 8 h. Our results suggest that thermochemotherapy in vivo is likely to be most effective with rapid infusions of DDP or MMC.

Lack of development of thermotolerance in early progenitors of murine bone marrow cells.

We have studied the sensitivities of four hematopoietic stem cell types to heat stress as well as their abilities to develop thermotolerance. Granulocyte-macrophage colony forming units were the most heat resistant bone marrow progenitors tested. Of the erythroid progenitors tested, erythrocyte colony forming units were more resistant than the two more primitive erythrocyte burst forming units. To determine their ability to develop thermotolerance, hematopoietic precursors were heated in vivo at 43 degrees C for 30 min. At various times thereafter the hematopoietic stem cells were flushed from female C3Hf/Sed mouse preheated tibia. The bone marrow cell suspensions were then heated in vitro and plated for colony formation. The four stem cell precursors differed markedly in their abilities to develop thermotolerance. The thermotolerance induced in granulocyte-macrophage colony forming units reached a maximum at 3-6 h after heating and disappeared by 24-48 h. The thermotolerance in erythrocyte colony forming units (0.5 units erythropoietin/ml media) reached a maximum at 3-6 h and disappeared by 48-72 h. The maximum level of thermotolerance reached by granulocyte-macrophage colony forming units and erythrocyte colony forming units was approximately the same. On the contrary, the two more primitive erythrocyte precursors which were grown by the addition of 2.5 and 5 units erythropoietin/ml of media do not develop thermotolerance.

Hyperthermic potentiation of cis-diamminedichloroplatinum(II) cytotoxicity in Chinese hamster ovary cells resistant to the drug.

The cytotoxic and pharmacological properties of hyperthermia and cis-diamminedichloroplatinum(II) (DDP) were studied in DDP-sensitive and DDP-resistant Chinese hamster ovary cells in vitro. Cytotoxicity was measured by cell survival using colony formation assay and cellular platinum levels were determined by atomic absorption spectrophotometry. Hyperthermia potentiated DDP cytotoxicity in both DDP-sensitive and DDP-resistant Chinese hamster ovary cells. Dose enhancement ratios increased from 1.4 to 6.5 over the temperature range of 39-43 degrees C. Cellular accumulation of platinum at 37 degrees C in the sensitive cells was 2.3- to 3.3-fold greater than that in the drug-resistant cells. Cellular accumulation of DDP was increased by factors of 1.5 and 2.2 at elevated temperature. DDP resistance did not confer cross-resistance to heat alone. The results suggest that hyperthermia could be used to circumvent DDP resistance.

Interaction of amphotericin B and 43 degrees hyperthermia.

At 43 degrees (but not at 41 degrees), the polyene antibiotic amphotericin B effectively inactivates mammalian cells in vitro even at doses which are used prophylactically, routinely, and continuously in some tissue culture laboratories. The greatly enhanced killing may reflect interactions between the drug and hyperthermia at the level of the cells' plasma membrane. A similar enhancement of cell killing at 43 degrees was seen when cells were exposed to nonisotonic salt solutions. Another polyene, nystatin, shows no temperature dependence, at least over the dose range examined, while another antifungal agent, polymyxin B, does so only at very high doses. The in vitro thermosensibility of cells to amphotericin B is reflected in vivo: EMT-6 murine tumor cells were killed much more efficiently in situ at 43 than at 37 degrees. Amphotericin B may be a useful agent in multiple drug thermochemotherapy.