The effect of chewing gum use on in situ enamel lesion remineralization.

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).     

Urine kidney injury molecule-1: a potential non-invasive biomarker for patients with renal cell carcinoma

Background

KIM-1 staining is upregulated in proximal tubule-derived renal cell carcinoma (RCC) including clear renal cell carcinoma and papillary renal cell carcinoma, but not in chromophobe RCC (distal tubular tumor). This study was designed to prospectively examine urine KIM-1 level before and 1 month after removal of renal tumors.

Patients and design

A total of 19 patients were eventually enrolled in the study based on pre-operative imaging studies. Pre-operative and follow-up (1 month) urine KIM-1 levels were measured. The urine KIM-1 levels (uKIM-1) were then normalized to urine creatinine levels (uCr). Renal tumors were also stained for KIM-1 using immunohistochemical techniques.

Results

The KIM-1-negative staining group included 7 cases, and the KIM-1-positive group consisted of 12 cases. The percentage of KIM-1-positive staining RCC cells ranged from 10 to 100 %, and the staining intensity ranged from 1+ to 3+. In both groups, serum creatinine levels were both significantly elevated after nephrectomy. In the KIM-1-negative group, uKIM-1/uCr remained at a similar level before (0.37 ± 0.1 ng/mg Cr) and after nephrectomy (0.32 ± 0.01 ng/mg Cr). However, in the KIM-1-positive group, elevated uKIM-1/uCr at 1.20 ± 0.31 ng/mg Cr was significantly reduced to 0.36 ± 0.1 ng/mg Cr, which was similar to the pre-operative uKIM-1/uCr (0.37 ± 0.1 ng/mg Cr) in the KIM-1-negative group.

Conclusion

Our small but prospective study showed significant reduction in uKIM-1/uCr after nephrectomy in the KIM-1 positive group, suggesting that urine KIM-1 may serve as a surrogate biomarker for kidney cancer and a non-invasive pre-operative measure to evaluate the malignant potential of renal masses.     

Color changing photonic crystals detect blast exposure

Blast-induced traumatic brain injury (bTBI) is the "signature wound" of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, warfighters with bTBI may not receive appropriate medical care and are at risk of being returned to the battlefield. Accordingly, we have created a colorimetric blast injury dosimeter (BID) that exploits material failure of photonic crystals to detect blast exposure. Appearing like a colored sticker, the BID is fabricated in photosensitive polymers via multi-beam interference lithography. Although very stable in the presence of heat, cold or physical impact, sculpted micro- and nano-structures of the BID are physically altered in a precise manner by blast exposure, resulting in color changes that correspond with blast intensity. This approach offers a lightweight, power-free sensor that can be readily interpreted by the naked eye. Importantly, with future refinement this technology may be deployed to identify soldiers exposed to blast at levels suggested to be supra-threshold for non-impact blast-induced mild TBI.     

Malignant melanoma in Europe: changes in mortality rates (1970-90) in European Community countries

Reducing mortality, especially premature death, is a major goal of the fight against cancer. In this study, we have analyzed trends in malignant melanoma (MM) mortality in the European Community (EC) as a whole and for each country. The data (obtained from the World Health Organization data bank) have been analyzed for the period 1970-90, by age groups (20-44, 45-64, 65-74, 75+ years). Trends are presented as percentage change of mortality rate for each three-year period in comparison with the rate in the first one (1970-72). The mortality from MM in the EC as a whole increased for both genders (men, +89.2 percent; women, +72.6 percent), with statistically significant trends in all age classes. Northern countries experienced mortality changes about 30 to 50 percent less than the EC average increase. Greater changes were seen in southern European countries, in which recent standardized rates are near to those observed in northern European populations. Among Mediterranean people, the highest increase (more than fourfold) was observed in Spain. The significant increase found for the younger age class makes unlikely the risk of misclassification with other skin cancers. No future decrease in MM mortality in the EC is indicated from these data.     

Duration of chemotherapy in small cell lung cancer: a Cancer Research Campaign trial

A total of 610 patients with small cell lung cancer were entered into a randomised trial designed to assess the effect of duration of initial chemotherapy on survival. Patients were randomised to receive either four or eight courses of cytotoxic chemotherapy with cyclophosphamide, vincristine and etoposide and also randomised to receive, on disease progression, either second line chemotherapy (methotrexate and doxorubicin) or symptomatic treatment only. In the whole study 196 (32.1%) had limited disease and 414 (67.9%) extensive disease. During initial chemotherapy the response rate (complete and partial responses) after four courses of treatment was 61% with no significant increase in patients receiving eight courses (63%). In those randomised to receive relapse chemotherapy the response rate was improved slightly for those who had originally received four courses of chemotherapy (25.6%) over those receiving eight (18.7%). The overall results show that of the four possible treatment randomizations, four courses of chemotherapy alone is inferior in terms of overall survival (30 weeks median survival) to the other three treatment options (39 weeks median survival, P less than 0.01). In patients responding to initial chemotherapy the disadvantage of four courses of chemotherapy alone was apparent (median survival of 40 weeks versus 49 weeks, P = 0.003) but not if drug treatment was given on relapse. The study shows that limiting treatment to four courses of chemotherapy alone is associated with inferior survival, but this is not the case if chemotherapy is given at relapse.     

An evaluation of chemical photoreactivity and the relationship to phototoxicity

The existing regulatory guidance for photosafety testing of new drug products states that studies are warranted for those chemicals that both absorb light in the range of 290–700 nm, and that are either applied locally/topically, or “reach” (EMEA)/“significantly partition” (FDA) to the skin or eyes. The initial in vitro study recommended for the assessment of phototoxic potential is the 3T3 Neutral Red Uptake (NRU) Assay. The current study was undertaken to establish superior triggers for the initiation of biological photosafety testing. In this study, photophysical and photochemical parameters for 40 drug or drug-like molecules were studied. Principal Component Analysis (PCA), Partial Least Squares-Discriminant Analysis (PLS-DA), and a fivefold cross-validation PLS algorithm were used to evaluate the relationship between subsets of photophysical and photochemical parameters with the 3T3 NRU PIF/MPE (Photo Irritation Factor/Mean Photo Effect) results. The parameters most indicative of a 3T3 NRU positive PIF or MPE score were the extent of degradation in solution, the quantum yield of formation of singlet oxygen and the relative formation of superoxide anion. The results demonstrate that while absorption of light is critical to the induction of a light-induced process, it is the resultant events that may be used to predict the 3T3 NRU assay result. It is therefore proposed that the trigger for photosafety testing be revised to include a molecular basis for photoreactivity. From this limited investigation, estimated thresholds leading to 3T3 NRU positive results due to photodegradation, formation of singlet oxygen quantum yield or a relative superoxide anion formation value are proposed.     

Nod1 and Nod2 regulation of inflammation in the Salmonella colitis model

The pattern recognition molecules Nod1 and Nod2 play important roles in intestinal homeostasis; however, how these proteins impact on the development of inflammation during bacterial colitis has not been examined. In the streptomycin-treated mouse model of Salmonella colitis, we found that mice deficient for both Nod1 and Nod2 had attenuated inflammatory pathology, reduced levels of inflammatory cytokines, and increased colonization of the mucosal tissue. Nod1 and Nod2 from both hematopoietic and nonhematopoietic sources contributed to the pathology, and all phenotypes were recapitulated in mice deficient for the signaling adaptor protein Rip2. However, the influence of Rip2 was strictly dependent on infection conditions that favored expression of the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (TTSS), as Rip2 was dispensable for inflammation when mice were infected with bacteria grown under conditions that promoted expression of the SPI-1 TTSS. Thus, Nod1 and Nod2 can modulate inflammation and mediate efficient clearance of bacteria from the mucosal tissue during Salmonella colitis, but their role is dependent on the expression of the SPI-2 TTSS.     

Electrode recovery potential

In some instances the same electrodes are used for stimulation and then for recording a bioelectric event immediately after the stimulus. However, after the current pulse there remains an electrode potential that decays quasiexponentially. We have designated this falling potential the electrode-recovery potential. This study investigated the recovery potentials of single electrodes of rhodium, stainless steel, platinum and platinum-iridium in contact with 0.9% saline at room temperature (25°C) over a current density ranging from 0.1 to 100 mA/cm² using a constant-current pulse. In all cases, with increasing current density, there was a decrease in the time for the electrode potential to fall to one half of the immediate post-stimulus value. Above about 20 mA/cm² the decrease in recovery time was smooth with increasing current density. Below 20 mA/cm², the recovery time was slightly irregular. The shortest recovery times were for platinum and platinum-iridium. The largest decrease in recovery time with increasing current density was for stainless steel, which decreased 10 fold from 0.1 to 100 mA/cm². The recovery time for rhodium decreased about three-and-one half fold over the same current density range. It was found that the waveform of the recovery potential is not a simple exponential because the Warburg and Faradic components of the electrode-electrolyte interface are current-density dependent. In general, for all current densities studied (0.1–100 mA/cm²), there was a sudden initial fall in electrode potential with cessation of current flow, followed by a very gradual nonexponential decrease in potential.