Use of autofluorescence and fluorescent probes as a potential diagnostic tool for oral cancer: A systematic review

IntroductionThe prognosis of patients with Oral squamous cell carcinoma (OSCC) are directly related to the stage of development of the tumor at the time of diagnosis, but it is estimated an average delay in diagnosis of 2–5 months. New non-invasive techniques for the early diagnosis of OSCC are being developed, such as methodologies to detect spectral changes of tumor cells. We conducted a systematic review to analyze the potential use of autofluorescence and/or fluorescent probes for OSCC diagnosis.Material and MethodsFour databases (PubMed, Scopus, Embase and Web of Science) were used as research sources. Protocol was registered with PROSPERO. It was included studies that evaluated tissue autofluorescence and/or used fluorescent probes as a method of diagnosing and/or treatment of oral cancer in humans.ResultsForty-five studies were selected for this systematic review, of which 28 dealt only with autofluorescence, 18 on fluorescent probes and 1 evaluated both methods. The VELscope® was the most used device for autofluorescence, exhibiting sensitivity (33%–100%) and specificity (12%–88.6%). 5-Aminolevulinic acid (5-ALA) was the most used fluorescent probe, exhibiting high sensitivity (90%–100%) and specificity (51.3%–96%). Hypericin, rhodamine 6 G, rhodamine 610, porphyrin and γ-glutamyl hydroxymethyl rhodamine green have also been reported.ConclusionThus, the autofluorescence and fluorescent probes can provide an accurate diagnosis of oral cancer, assisting the dentist during daily clinical activity, but it is not yet possible to suggest that this method may replace histopathological examination.     

A semi-quantitative direct contact assay using fluorescein diacetate and L929 mouse fibroblasts in monolayer culture

Summary A semi-quantitative procedure is described for measuring cell viability after short-term exposure to a test substance using a monolayer culture. Test substances are placed in direct contact with cell monolayers for various time intervals. The substances are removed and the monolayers are incubated in the presence of fluorescein diacetate. Monolayers are viewed under a fluorescent microscope and the percentage of fluorescing (viable) cells is estimated. The method is suitable for examining cytotoxic effects at short times of exposure and for discriminating between test substances that give similar, low toxicity endpoints in standard 24-h assays.     

化学染发剂和冷烫精的毒性及对人体健康影响的调查研究

本文通过化学染发剂和冷烫精对大白鼠骨髓多染红细胞，毛囊细胞的微核实验及人群健康影响调查，结果表明化学染发剂，冷烫清具有较强致突变作用，两者同时使用致突变明显增强，并提出研制高效无毒染发剂和加强防护的重要性。     

Substrate specificity of the luminal Na+-dependent sulphate transport system in the proximal renal tubule as compared to the contraluminal sulphate exchange system

The efflux of [³⁵S]sulphate from the lumen of the proximal renal tubule into tubular cells of rats was measured by the stop-flow tubular-lumen microperfusion technique. The transport parameters obtained and the apparent K _i values of competing substrates were compared with those of the contraluminal influx of [³⁵-S]sulphate from the interstitium into tubular cells. For the luminal sulphate efflux a K _m(l, SO ₄ ^2– ) of 0.8 mmol/l and a J _max(l, SO ₄ ^2– ) of 0.2 pmol s^–1 cm^–1 were found. The corresponding contraluminal values were K _m(cl,SO ₄ ^2– ) 1.4 mmol/l and J _max(cl, SO ₄ ^2– ) 1.2 pmol s^–1 cm^–1. Omission of Na⁺ from the perfusates reduced the luminal efflux of sulphate by 83%, while the contraluminal influx of sulphate was not changed. Increase in HCO ₃ ^– concentration inhibited both luminal efflux and contraluminal influx of sulphate, while a change of pH from 6.0 to 8.0 was without effect. Comparing the apparent K _i(SO ₄ ^2– ) values for luminal and contraluminal sulphate transport, a relationship close to 11 was seen for some inorganic substrates with tetrahedral molecular structure (thio-sulphate, sulphate, molybdate and selenate). The same holds for phosphate, while for oxalate the contraluminal K _i(SO ₄ ^2– ) value was lower than the luminal one (1.2 and 4.5 mmol/l). Some of the dicarboxylates and disulphonates tested show the same affinity to the luminal Na⁺-dependent sulphate transporter and the contraluminal sulphate exchange system, whereas most of the benzene carboxylate and benzenesulphonate derivatives tested exhibit higher luminal than contraluminal k _i values. The inhibitory potency increased with rising numbers of substituents on the benzene ring. This effect was more pronounced for the contraluminal sulphate transporter. In general, only disulphonates and analogues as well as similarly structured compounds (5-sulphosalicylate, 2-hydroxy-5-nitrobenzenesulphonate, eosine-5-isothiocyanate) have a good inhibitory potency toward the luminal sulphate transporter [apparent K _i 0.9–3.1 mmol/l]. All the tested sulphamoyl and phenoxy diuretics, and fluorescein and phenolphthalein dyes showed no or a smaller inhibitory potency to the luminal sulphate transport system than to the contraluminal. The most effective inhibitors of both sulphate transport systems are 8-anilino-1-naphthalenesulphonate, orange G, and H₂-DIDS. The data indicate that the Na⁺-dependent luminal and the Na⁺-independent contraluminal sulphate transport systems accommodate a similar spectrum of anionic substrates, whereby the inhibitory potency against the luminal Na⁺-dependent sulphate transport system is identical or smaller than against the contraluminal transporter.     

Regulation of intracellular pH in cultured bovine retinal pigment epithelial cells

Regulation of intracellular pH (pH_i) in bovine retinal pigment epithelium (RPE) was investigated in cell culture. pH_i was measured using the pH-sensitive absorbance of intracellularly trapped 5 (and 6)-carboxy-dimethyl-fluorescein (CDMF). (1) Regulation of pH_i after induction of an acid load by removal of NH₄Cl could be blocked either totally by removal of extracellular sodium, or subtotally (about 90%) by application of amiloride (1 mmol/l). Additional flux measurements revealed a dose-dependent, amiloride-sensitive²²Na⁺-uptake into Na⁺-loaded cells. Both results suggest the presence of a Na⁺/H⁺ antiport.(2) When alkalinization of the cells was induced by preincubation with 50 mmol/l acetate in HCO ₃ ^– -Ringer's and subsequent removal of the weak acid, the following regulation was dependent on the presence of extracellular chloride. This process could be blocked with DIDS (1 mmol/l), suggesting the presence of a Cl^–/HCO ₃ ^– exchange mechanism.(3) We found no evidence for a Na⁺/HCO ₃ ^– -cotransport, which had been postulated to be present in RPE by others. We conclude that two processes are involved in regulation of pH_i in RPE: A Na⁺/H⁺ antiport responsible for recovery of pH_i from acid load, and a DIDS-sensitive Cl^–/HCO ₃ ^– exchange mechanism responsible for recovery of pH_i after alkalinization.Parts of this work jhave been published in abstract from [20, 21]     

In vitro genotoxicity of dyes present in colored smoke munitions

Genetic toxicology studies were conducted on organic dyes and mixtures used in colored smoke munitions. The dyes studied included Solvent Red 1; two different batches (Lot 1 and Lot 2) of Disperse Red 11; terephthalic acid; and a mixture of 25 parts Solvent Red 1, 5 parts Disperse Red 11, and 16 parts terephthalic acid. The dyes were evaluated for their ability to produce mutations in Salmonella bacterial strains and in Chinese hamster ovary (CHO) cells. The dyes were also tested in CHO cells to determine cytotoxicity and the induction of sister chromatid exchanges and chromosome aberration. None of the dyes were genotoxic in the standard Ames assay using bacterial strain TA1535 or TA100 with or without the addition of S-9 or in TA98 and TA1538 without S-9. With S-9, Disperse Red 11 (Lot 2) showed significant mutagenic activity in TA98 and TA1538 which increased as a function of S-9 concentration. However, the maximum level of mutagenic activity detected was low (3.8 revertants/micrograms). The azo dye Solvent Red 1 was also negative in a pre-incubation assay designed to reduce azo compounds to free amines. Solvent Red 1 was cytotoxic to mammalian cells, caused a significant increase in SCE, but was not mutagenic or clastogenic. Disperse Red 11 (Lot 1 and Lot 2) were not cytotoxic or clastogenic but produced an increase in cell cycle time and SCE frequency. Only Disperse Red 11 (Lot 2) increased mutations in the CHO/hypoxanthine-guanine phosphoribosyltransferase (HGPRT) assay. The mutagenic activity of the dye mixture was not significant, suggesting no synergistic interaction between the dyes. These studies demonstrated that none of the dyes was clastogenic and that a contaminant in Disperse Red 11 (Lot 2) may be responsible for the weak mutagenic activity in both mammalian and bacterial cell systems.     

Extraction of organic acids by ion-pair extraction with tri-n-octylamine - VIII. Identification of synthetic dyes in pharmaceutical preparations

Synthetic dyes were extracted from syrups, oral suspensions, tablets, gelatin capsules, suppositories and granules by ion-pair formation with tri-n-octylamine (TnOA) and back-extracted with perchlorate ions. Identification was performed by TLC on cellulose layers and by reversed phase ion-pair HPLC.     

Real-time visual detection of Pi released by flagellar dynein ATPase

 Using a novel fluorescent probe for P_i, a method for the direct visualization of P_i release from reactivated flagellar dynein ATPase has been developed. The probe undergoes a fluorescence increase when it binds P_i. The technique involves simultaneous imaging of demembranated sperm tails by epi-fluorescence and dark-field microscopy, and the use of the caged ATP technique for axoneme reactivation. To limit diffusion and thus maintain the released P_i within the observed field of view, the assay is carried out within a minute droplet under oil (volume 5–15 pl). The video output of a recursively filtered ICCD camera is used to visualize the fluorescence signal, which is subsequently digitized and automatically analysed on a PC. A major advantage of this technique is that it enables simultaneous analysis of the ATP-utilization rate and the motility of the reactivated axonemes. Received: 24 November 1998 / Received after revision: 21 January 1999 / Accepted: 22 January 1999     

Tumors of the urinary bladder in painters: a case-control study

In a case-control study, 403 male patients with a diagnosis of "bladder tumor" and (as controls) 426 patients suffering from prostate disease were investigated. The results of this study indicate that past employment as a painter was associated with an excess risk of bladder tumor. The relative risk of bladder tumor estimated for painters was 2.76. The possible role of benzidine-based azodyes (or azodyes based on substituted benzidines) as a carcinogenic risk factor for painters is discussed.