The importance of schedule in whole body thermochemotherapy.

PURPOSE: To determine an effective triple-agent schedule combining fever-range whole body thermal therapy (FR-WB-TT) with cisplatin and gemcitabine by optimizing the timing of drug with heat, and drug with drug. MATERIALS AND METHODS: Using an orthotopically implanted syngeneic breast adenocarcinoma in an immunologically normal female Fischer rat model, we investigated various schedules of a thermochemotherapy regimen combining FR-WB-TT with chemotherapy agents, cisplatin and gemcitabine. Differently timed combinations of a) cisplatin with FR-WB-TT, b) gemcitabine with FR-WB-TT, and c) cisplatin with gemcitabine were examined for anti-tumor efficacy and toxicity. A combination of the three agents based on the optimal two-agent schedules was then tested. RESULTS: The greatest primary tumor and axillary metastasis growth delay and lowest toxicity was induced with administration of cisplatin 24 h prior to gemcitabine and cisplatin 24 h prior to simultaneous gemcitabine and FR-WB-TT. Administering cisplatin 24 h prior to gemcitabine was more effective and less toxic than giving the two drugs simultaneously or gemcitabine prior to cisplatin. Survival was greatest when gemcitabine and FR-WB-TT were administered 24 h after cisplatin, even with reduced drug doses. One complete cure resulted from the triple agent treatment. CONCLUSIONS: The relative timing of agents in multiple modality treatments is critically important in achieving tumor control or cures, and in reducing toxicity. Optimizing the relative timing of multiple agents in thermochemotherapy allows use of lower drug doses to achieve maximal anti-tumor efficacy and minimal toxicity.

The cariostatic potential of cheese: cooked cheese-containing meals increase plaque calcium concentration.

OBJECTIVE: Eating cheese by itself increases plaque calcium concentration - which is probably one mechanism of the well-established action of cheese in reducing experimental caries. The objective of the present study was to determine whether consumption of cheese as part of a cooked, mixed meal (ie as it is habitually consumed) is able to increase plaque calcium concentration. DESIGN: Plaque samples were obtained from 16 adult volunteers before and 5 minutes after consumption of either a 15 g cube of cheese, one of two cheese-containing test meals, or one of two control meals. Each subject tested each of the four meals on a separate occasion. Plaque calcium concentration was measured using atomic absorption spectrophotometry. RESULTS: The test meals increased plaque calcium concentrations to a significantly greater magnitude than the control meals (P < 0.05). A non-significant trend was observed towards a larger magnitude of change in plaque calcium concentration in the 8 subjects with the lowest, compared with the 8 subjects with the highest baseline concentration. CONCLUSION: The findings suggest that cheese-containing meals increase plaque calcium concentration and thus probably protect against dental caries.

Review of fluoride research since 1959.

The evidence for the two main hypotheses proposed for the mode of action of F in reducing caries is reviewed. The current conclusion is that low concentrations of F in plaque, which need frequent renewal, favour remineralization of dental tissue (i.e. a net reduction of demineralization) in the later stages of a cariogenic episode. This replaces the other view that a high concentration of F in the tooth mineral reduces its solubility.

Effect of altered duration of 41.5 degrees C whole body hyperthermia in combination with cis-diamminedichloroplatinum (II) on tumor and normal tissue apoptosis and tumor response in rats.

We investigated the correlation between antitumor efficacy and kinetics of tumor and normal tissue apoptosis when cis-diamminedichloroplatinum (II) (CDDP) was combined with two different durations of whole body hyperthermia [SH-WBH, at 41.5 degrees C for 1 h (1 h WBH) or 2 h (2 h WBH)]. Rats bearing a mammary adenocarcinoma (MTLn3) were treated with 1 or 2 h WBH CDDP and then assessed for tumor growth delay (TGD). A separate study examined the amount of induced apoptosis in tumor and normal tissue (thymus and ileum) over 96 h following the same treatments. 1 h WBH + CDDP increased the TGD to 10.5+/-0.5 days, which was not statistically different from the TGD of 12.3+/-0.5 days obtained with 2 h WBH + CDDP. The area under the curve (AUC) of percentage tumor apoptosis for 1 h WBH + CDDP was 50% of that of 2 h WBH + CDDP. The AUC of percentage thymus apoptosis for 1 h WBH + CDDP was 25% of that of 2 h WBH + CDDP, and the AUC of the score of ileal apoptosis for 1 h WBH + CDDP was 81% of that of 2 h WBH + CDDP. These data indicate that while 1 h WBH + CDDP induced less tumor apoptosis than 2 h WBH + CDDP, antitumor activity was enhanced to a similar degree by both 1 h and 2 h WBH + CDDP, and since 1 h WBH + CDDP caused less normal tissue apoptosis than 2 h WBH + CDDP, a 1 h duration of WBH + CDDP may be a therapy that is both, as effective as, and safer than a 2 h duration of WBH + CDDP.

Therapeutic efficacy and apoptosis and necrosis kinetics of doxorubicin compared with cisplatin, combined with whole-body hyperthermia in a rat mammary adenocarcinoma.

We have compared the therapeutic efficacy as well as the kinetics of treatment-induced apoptosis and necrosis of the maximum tolerated dose (MTD) of doxorubicin (DOX) or cisplatin (CDDP) combined with long-duration, low-temperature whole-body hyperthermia (LL-WBH, at 40.0 degrees C for 6 hr), with the combination of the MTDs of either DOX or CDDP with short-duration, high-temperature WBH (SH-WBH, at 41.5 degrees C for 2 hr), in a rat mammary adenocarcinoma (MTLn3). The MTD of LL-WBH + DOX resulted in increased therapeutic efficacy, compared with the MTD of DOX alone and SH-WBH + DOX. The MTD of LL-WBH + CDDP, however, did not increase therapeutic efficacy, when compared with the MTD of CDDP alone or SH-WBH + CDDP. The MTD of LL-WBH + DOX caused a significant delay in the development of spontaneous axillary lymph node (ALN) metastasis and tended to cause longer mean survival, compared with SH-WBH + DOX. The peak of treatment-induced apoptosis was higher for the MTD of DOX + LL-WBH, compared with SH-WBH + DOX, whereas the apoptosis peak of the MTD of SH-WBH + CDDP was higher than that of LL-WBH + CDDP. The most extensive levels of tumor necrosis appeared to occur earlier with SH-WBH alone and the MTD of SH-WBH + DOX or CDDP than with other groups. Our results suggest that LL-WBH + DOX may be a promising therapy for breast cancer, and the extent of treatment-induced tumor apoptosis appears to correlate with antitumor response for MTDs of LL-WBH + DOX and SH-WBH + DOX, but not for the MTDs of CDDP with SH-WBH or LL-WBH.

Optimal duration of whole body hyperthermia when combined with cis-diaminne-1,1-cychlobutane dicarboxylate platinum (II) (carboplatin).

Minimizing normal tissue toxicity can enhance the therapeutic gain of thermochemotherapy. For this purpose, we investigated the optimal duration of whole body hyperthermia (WBH) (41.5 degrees C) when administered simultaneously with carboplatin (CBDCA). Using a transplantable fibrosarcoma in Fischer 344 rats, we measured tumor growth delay (TGD) as well as normal tissue toxicities (body weight loss, thrombocytopenia) induced by various durations of WBH (0.5, 1.0, 1.5, 2.0 or 2.5 hours) when combined with CBDCA (30 mg/kg, i.v.). When combined with CBDCA, 1.0 hour WBH increased the TGD compared to 0.5 hour of WBH, but with WBH durations greater than 1.0 hour, the TGD did not further significantly increase. Measuring CBDCA-induced myelosuppression, the platelet count on day 6 post-treatment decreased from a control mean of 6.8 x 10(8)/ml to 1.8 x 10(8)/ml after 2.5 hour WBH exposure in a duration-dependent manner (p < 0.001). To estimate the specific therapeutic efficacy (STE), we calculated a ratio of TGD to myelosuppression (thrombocytopenia). Compared to other WBH exposure times, 1.0 hour duration of WBH combined with CBDCA produced the highest STE (2.8) and over 1.5 hour duration of WBH did not result in any additional increase in STE. We conclude that 1.0 hour WBH exposure is optimal when combined with CBDCA in order to maximize the therapeutic gain.

Long duration-mild whole body hyperthermia of up to 12 hours in rats: feasibility, and efficacy on primary tumour and axillary lymph node metastases of a mammary adenocarcinoma: implications for adjuvant therapy.

The feasibility and efficacy of low temperature (40 degrees C) long duration whole body hyperthermia (LL-WBH) was investigated in rats bearing a highly metastatic mammary adenocarcinoma (MTLn3). We compared the treatment effects of various durations of LL-WBH (40 degrees C for 2-12 h) to that of conventional short duration-high temperature WBH (SH-WBH, 41.5 degrees C for 2 h). SH-WBH, 2 h LL-WBH, and 4 h LL-WBH resulted in only modest primary tumour growth delays (TGDs) of 0.9, 1.1 and 1.8 d (days) respectively. In contrast, significantly increased TGDs of 2.8, 3.2, 2.6, and 3.1 d were achieved with 6, 8, 10 and 12 h LL-WBH, respectively (p < 0.05 compared to SH-WBH, 2 h-LL-WBH, and 4 h-LL-WBH). Notably, LL-WBH reduced the incidence of axillary lymph node metastasis at 14 days post-treatment, from 100% in normothermic controls and 92% after SH-WBH, to 33, 40, 50, and 60% following 4, 6, 8 and 10 h LL-WBH respectively. When the duration of LL-WBH was extended to 12 h, no reduction in axillary lymph node metastasis was observed. Normal tissue toxicity of LL-WBH appeared to be minimal and LL-WBH durations of up to 12 h were well tolerated. These data show that LL-WBH for durations of from 4 to 10 h has greater antitumour activity than SH-WBH, against mammary adenocarcinoma, suggesting that LL-WBH may have therapeutic potential in the treatment of malignant disease.

Apoptosis and necrosis occurring during different stages of primary and metastatic tumor growth of a rat mammary adenocarcinoma.

The pattern of spontaneous apoptosis and necrosis was investigated in an untreated, transplantable rat mammary adenocarcinoma (MTLn3) throughout the natural course of primary and metastatic tumor growth. The occurrence of spontaneous apoptosis was different when comparing primary to metastatic tumor growth. In the primary MTLn3 tumor growing at the mammary fat pad inoculation site we observed an inverse association between tumor growth and apoptosis. As the primary tumor increased in size, the extent of spontaneous apoptosis decreased. In contrast, an increase in apoptosis was associated with tumor growth of MTLn3 metastases in the axillary lymph node and the lung. In regard to necrosis, a similar pattern of increased necrosis was associated with tumor progression in both primary and metastatic tumors. Differences between primary and metastatic tumors in their pattern of spontaneous apoptosis may have important implications for the design of clinical treatment strategies.

Apoptosis in tumors and normal tissues induced by whole body hyperthermia in rats.

Apoptosis in tumor and normal tissues was examined in rats treated with whole-body hyperthermia (WBH; 41.5 degrees C for 2 h). WBH alone produced 0.5 day of tumor growth delay (TGD) in a fibrosarcoma and 5.8 days of TGD in the Ward colon carcinoma. This difference in WBH-induced TGD indicates that the fibrosarcoma is relatively resistant to WBH, whereas the Ward colon carcinoma is relatively heat sensitive. A quantitative histological assay for apoptosis demonstrated that the extent of apoptosis in the fibrosarcoma reached a maximum level of 19% 4 h after WBH and returned to the control level by 24 h. In contrast, WBH induced apoptosis with a peak value of 43% at 8 h in the Ward colon carcinoma, and the apoptotic level remained elevated above the control level until 48 h after WBH. Within normal tissues, the spleen and the lymph nodes showed WBH-induced apoptosis; however, the highest level of WBH-induced apoptosis as well as the most prolonged increase in apoptotic levels occurred in the thymus. The WBH-induced apoptosis in the thymus remained elevated above the control level until 48 h after WBH. Within the entire gastrointestinal tract, the small intestine was the most sensitive to WBH. Apoptotic cells were observed in the small bowel mucosa following WBH exposure. We also noted a minor WBH-induced increase in the apoptotic level in the bone marrow. Except for the case of the thymus, increased apoptotic levels in the normal tissues declined after peak levels at 4 h, and apoptosis above control levels was not seen beyond 12 h following WBH. Thus, within the normal tissues, WBH-induced apoptosis declined to basal levels within 12-48 h. These data indicate that both the extent and the kinetics of WBH-induced apoptosis differ between the two tumors and, meaningfully, between tumor and normal tissues. The extent and duration of apoptosis seem to correlate with tumor response to WBH.

Apoptosis in normal tissues induced by 5-fluorouracil: comparison between bolus injection and prolonged infusion.

The induction of apoptosis in normal tissues was histopathologically examined in rats treated with 5-fluorouracil (5-FU). 5-FU was administered by either bolus intravenous injection or 72-hr prolonged intravenous infusion (PIF). Bolus injection and PIF of 5-FU induced different kinetic profiles of apoptosis in the thymus, spleen and ileum. The bolus injections of 5-FU induced a greater extent of apoptosis in these tissues, compared to PIF 5-FU. These data indicate that the kinetics and extent of apoptosis induced by 5-FU depends on the schedule of the 5-FU administration, and that 5-FU-induced toxicity may be related to 5-FU-induced apoptosis in normal tissues.

Therapeutic efficacy of long duration-low temperature whole body hyperthermia when combined with tumor necrosis factor and carboplatin in rats.

This study examines the effects of a combined modality regimen of long duration-low temperature whole body hyperthermia (6 h at 40.0 degrees C; LL-WBH), recombinant human tumor necrosis factor-alpha (TNF) and carboplatin (CBDCA) on a transplantable fibrosarcoma as well as normal tissue. We compare LL-WBH with short duration-high temperature whole body hyperthermia (2 h at 41.5 degrees; SH-WBH). LL-WBH alone had no significant effect on tumor growth. Tumor growth delay (TGD) with TNF alone (0.1 days) and that with CBDCA alone (1.3 days) were significantly increased to 2.6 days (P < 0.05) and 2.8 days (P < 0.05), respectively, when combined with LL-WBH. Although TNF+CBDCA produced minimally increased TGD of 1.9 days, the combination of LL-WBH+TNF+CBDCA produced a significantly greater TGD of 5.6 days, compared to the other dual combinations (P < 0.01). There was no difference between TGDs for SH-WBH and LL-WBH in combination with TNF+CBDCA. Trimodality treatment-induced normal tissue toxicities, characterized by body weight loss, diarrhea, foot edema, and myelosuppression, were significantly greater in rats treated with SH-WBH+TNF+CBDCA, compared to LL-WBH+TNF+CBDCA. Histopathological examination also demonstrated that SH-WBH+TNF+CBDCA caused severe damage to the lymphoid tissues, intestinal tract, and peripheral microvasulature. We observed minimal histopathological changes observed in rats treated with LL-WBH+TNF+CBDCA. These data suggest that LL-WBH in combination with TNF and CBDCA has a greater therapeutic efficacy than SH-WBH.

Fluoride intake and its safety among heavy tea drinkers in a British fluoridated city.

Tea-drinking in very young children has been studied in a British city. The results suggested that the fluoride in tea would, in some cases, be sufficient to influence caries. Clinical findings to some extent supported this. The main purpose of the investigation reported here was to determine maximum possible fluoride intake in adults who were heavy tea drinkers in a fluoridated city and relate it to toxic thresholds. Heavy tea drinkers were traced through Health Visitors and voluntary organizations and the volumes and fluoride concentrations of their drinks were measured. Even the highest intake found (9 mg) is below the probable intake in Bartlett, Texas (8 ppm of fluoride), in relation to which no undesirable symptoms have been reported (Leone et al. 1954). This confirms the safety of fluoridation. The effects on fluoride concentration of evaporating soft and hard fluoride-containing waters to small bulk were compared. The results showed ceilings of 3 ppm of fluoride in hard water and about 14 ppm in soft water, much higher than the levels expected on the basis of the usually stated solubility of CaF2 (16 or 8 ppm of fluoride). However, under normal household conditions, it is most unlikely that dangerous levels of fluoride would be ingested from boiled water.

Increased therapeutic gain of combined cis-diamminedichloroplatinum (II) and whole body hyperthermia therapy by optimal heat/drug scheduling.

To maximize therapeutic gain, the timing sequence of whole body hyperthermia (WBH) and cis-diamminedichloroplatinum (II) (DDP) was examined. Normal tissue injury as well as growth of a s.c. transplanted fibrosarcoma were measured in F344 rats treated with variable schedules of WBH and DDP. Simultaneous application of DDP (2 mg/kg i.v.) with WBH (120 min at 41.5 degrees C) resulted in severe renal injury, body weight loss, and mortality; while sequential use of the modalities caused minimal to no toxicity. DDP or WBH alone produced only minimal tumor growth delay, whereas supraadditive antitumor effects occurred with all tested schedules of DDP combined with WBH, regardless of sequence or interval between the two modalities. We designated the ratio of antitumor effect to nephrotoxicity as specific therapeutic efficacy (STE). DDP given simultaneously with WBH produced the lowest STE (0.6-1.2), which was less than or equal to either DDP (STE = 1.2) or WBH (STE = 1.5) alone. On the other hand, schedules of DDP prior to and after WBH resulted in a STE of 1.8-3.0, a supraadditive effect. These results indicate that an optimal scheduling of DDP with WBH significantly improves therapeutic gain by reducing normal tissue injury while maintaining enhanced antitumor activity.

The effect of daily gum-chewing on salivary flow rates in man.

Following reports of increased salivary gland size and increased function, induced by increased mastication in animals, the effects of long-term, frequent gum-chewing on resting and stimulated flow rates were studied in human volunteers in separate experiments in Newcastle upon Tyne and in Toronto. In both experiments, unstimulated and stimulated saliva flow rates were measured in student volunteers at intervals of one or two weeks over a baseline period. Approximately half of the subjects were then given sugarless gum to be chewed (four pieces per day) over the experimental period; controls refrained from vigorous mastication. During (and, in Newcastle, after) the experimental period, salivary flow rates were measured at intervals, as before. In Newcastle unstimulated, but not stimulated, flow rates increased in the gum-chewing group and were still elevated (compared with controls) eight weeks following the experiment. In Toronto, the mean results showed no effect of gum-chewing, but the seven gum-chewers among the 11 subjects with low baseline flow rates (less than 0.3 mL/min) showed a 43% rise in unstimulated flow rate (p approximately 0.05). The results suggest that increased mastication, in the form of gum-chewing, can increase unstimulated flow rates, especially in those with low salivary function. In addition to short-term beneficial effects of sugarless gum, these long-term effects indicate the possibility of a beneficial effect in caries prevention.

Effect of eating cheese on Ca and P concentrations of whole mouth saliva and plaque.

A study was undertaken to examine the release of calcium and phosphate from cheese during mastication. Unstimulated saliva was collected for baseline analysis in the initial study followed by saliva collection after chewing different cheeses with and without biscuits. In the second study, volunteers who had abstained from tooth cleaning for 24 h had plaque samples taken from two quadrants, they then chewed cheese in their own personal eating manner, and a second sample of plaque was taken within 5 min. The results showed that the calcium ion concentration of the oral fluids rose from a mean of 30 micrograms/ml to between 200 and 540 micrograms/ml, depending on the type of cheese, but the phosphate concentration fell below baseline. The release of both ions tended to be less when the cheese was eaten with a biscuit. In the second study a highly significant rise in plaque calcium concentration was shown after eating cheese, but no consistent change in phosphate level was found. Acidic soft drinks, following eating, tended to reduce the plaque calcium levels, but no consistent change was found if tea or coffee was taken following the cheese consumption. It is suggested, from these findings, that cheese eaten alone at the very end of a meal raises plaque calcium and might be effective in reducing dental caries.

Effects of water-soluble components of cheese on experimental caries in humans.

The effect of water-soluble components of extra-old Cheddar cheese on experimental caries was tested by means of the seven-day intraoral cariogenicity test (ICT). Two bovine enamel blocks were placed in each buccal flange of the dental appliances of five volunteers. One side of each appliance (experimental) was dipped in a 25% water extract of the cheese for five min, while the other side (control) was dipped in de-ionized water. Immediately thereafter, the appliance was returned to the subject's mouth, and two 60-second rinses with 10% sucrose were performed. These procedures were repeated six times per day. The cheese-extract dippings reduced the cariogenicity of the sucrose by an average of 55.7% (p less than 0.01), as assessed by enamel microhardness. Neither the mean resting pH nor the mean minimum pH in response to sucrose was significantly different between the experimental and control sides. The concentration of calcium was significantly higher in plaque from the experimental side (32.44 micrograms/mg) as compared with the control side (19.36 micrograms/mg, p less than 0.01). The concentration of plaque phosphorus was higher on the experimental side (12.90 micrograms/mg) than on the control side (9.61 micrograms/mg); however, the difference was not statistically significant. These results show that cheese has one or more water-soluble components which reduce experimental caries in human subjects.

Acid diffusion analysis of different forms of fluoride in human dental plaque.

Fluoride concentration was determined by: (a) extraction with diphenylsilanediol after combustion of the plaque in an oxygen bomb; (b) acid diffusion from 0.5 M HClO4 for 16 h at room temperature; (c) acid diffusion from 4.6 M HClO4 for 16 h at room temperature; and (d) acid diffusion from 18 M H2SO4 for 16 h at 60 degrees C. The total fluoride was determined by all the diffusion procedures, and there was no evidence of a large proportion of the plaque fluoride being released only after treatment with strong acid (18 M H2SO4). When approx. 10 mg of plaque was extracted three times with 0.1 ml 0.5 M HClO4, 81 per cent of the fluoride was released by one 5 min extraction. After three extractions no further fluoride was detected when the residue was diffused from 4.6 M HClO4 for 16 h at room temperature. When larger plaque samples (21-66 mg) were extracted four times with 1 ml 0.5 M HClO4, 85 per cent of the fluoride was in the first extract, and none was detected in the fourth. Treatment of the residue with 18 M H2SO4 for 16 h at 60 degrees C released a further, small amount which may constitute up to 3 per cent of the total plaque fluoride. Thus the amount of tightly-bound plaque fluoride, released only by treatment with strong acid, is much smaller than previously believed.