, 2010 and Robinson et al., 2010) and TMS to this region selectively impairs semantic task performance when control demands are high (Whitney, Kirk, et al., 2011 and Whitney et al., 2012). The semantic control hypothesis predicts that this area should show increased activation for abstract relative to concrete words (referred to hereafter as an A > C effect) because their variable meanings require greater executive regulation.

check details A > C effects have been reported in IFG (Binder et al., 2009 and Wang et al., 2010) but they have not been linked specifically to executive control demands. Other researchers have suggested instead that IFG is involved in representing logical propositions that are key to the meaning of abstract concepts (Shallice & Cooper, 2013) or in integrating or “unifying” semantic knowledge of a word with prior context (Hagoort, 2005). Although most research has focused on the role of left IFG in semantic control, recent studies suggest that other regions, including posterior middle temporal gyrus, are also involved in this function (Noonan et al., 2010, Whitney, Jefferies, et al., 2011 and Whitney,

Kirk, et al., 2011). In contrast, the anterior temporal lobes1 (ATL) are associated with the representation of semantic knowledge. ATL involvement in multi-modal conceptual knowledge has been observed in studies using H2O-PET (Sharp et al., 2004 and Vandenberghe et al., 1996), distortion-corrected fMRI (Binney et al., 2010 and Visser and Lambon Ralph, 2011), MEG (Marinkovic et al., 2003) and rTMS (Pobric et al., 2007 and Pobric et al., 2010). It is demonstrated most strikingly in the learn more syndrome of semantic dementia, in which atrophy to this area results in selective yet progressive and eventually profound impairment to verbal and non-verbal semantic knowledge (Bozeat et al., 2000 and Patterson et al., 2007). According to the representational substrates perspective, areas of ATL specialised for representing verbal aspects of knowledge should show an A > C effect while the reverse should be true for areas specialised selleck chemicals llc for representing visual object properties. In other words, the likelihood of observing

concreteness effects in the ATL should depend on the degree to which portions of this brain region are specialised for verbal versus visual processing. Some parts of the ATL do show graded specialisation of this sort. The superior ATL shows greater activation for semantic processing of auditory and verbal stimuli, relative to pictures (Moore and Price, 1999, Visser et al., 2012 and Visser and Lambon Ralph, 2011). This specialisation may arise because this area is strongly connected to primary auditory processing regions in posterior STG (Binney, Parker, & Lambon Ralph, 2012). Consistent with the idea that abstract words are especially dependent on verbal processing regions, A > C effects have been observed in this area in previous studies (Binder et al., 2009, Noppeney and Price, 2004, Tettamanti et al.

The request by authorities to remove thiomersal caused fear amongst the general public concerning the toxicity of vaccine components, and negatively impacted overall vaccine uptake and acceptance. In the subsequent years, following authority guidance, vaccine manufacturers have removed thiomersal from most paediatric vaccines and reduced the amount of thiomersal in the few remaining vaccine formulations in a common effort to remove mercury from vaccines and re-establish public confidence in immunisation programmes. However, the WHO acknowledges that making changes to the thiomersal content of licensed

vaccines containing this preservative is a complex issue requiring careful consideration. Any change in the formulation of thiomersal-containing vaccines may

LDK378 in vivo have an important impact on the quality, safety and efficacy of the vaccine Selleckchem PCI-32765 and therefore any decision regarding the elimination or reduction of thiomersal in vaccines should be based on a demonstrated adverse effect. New-generation vaccines are subject to increased safety testing throughout the vaccine development process. The safety assessment has been enhanced throughout preclinical, clinical and post-licensure studies. All safety assessments performed have the objective of increasing the likelihood of identifying possible safety concerns and consequently of taking the necessary measures to remove or minimise them. Available data indicate that licensed vaccines have a benefit–risk profile where the benefits clearly surpass the risks. This short overview of vaccine development processes and post-licensure surveillance describes how clinical development and assessment of vaccines is constantly improving and evolving. It also illustrates else how changes to the processes over time have helped to

generate the robust data needed to enhance the benefit–risk profiles of new vaccines. There is now a large number of diseases for which licensed vaccines are available (Appendices, Supplementary Table 6), however, we are still faced with challenges in the form of diverse populations and complex pathogens; these require further novel approaches to antigen selection, manufacture, presentation and delivery. The main areas of new vaccine research are the subject of Chapter 6 – Vaccines of the future. “
“Key concepts ■ New tools are available to aid vaccine manufacturers in meeting challenges for new vaccine development □ Many technologies that are already available continue to be improved, including adjuvants and novel vaccine delivery platforms The advances made in vaccine technology since Edward Jenner vaccinated the young James Phipps against smallpox have had a spectacular impact on human health over the last two centuries (see Chapter 1 – Vaccine evolution).

The results supported previous in vitro ( Bertolazzi et al., 1991 and Emerick et al., 2012a)

screening that suggested (+)-methamidophos as the more likely than (−)-methamidophos learn more to induce OPIDN in humans and hens. In the present study hens were given pure enantiomers and racemic with proper protection (atropine) from cholinergic crisis. Because methamidophos can cause OPIDN in people (McConnell et al., 1999 and Senanayake and Johnson, 1982), early inhibition of NTE activity of at least 70% is generally used to identify OPIDN potential. In this study, such inhibition was noted with 500 mg/kg TOCP. Although NTE inhibition with (+)-methamidophos was less than that, it could be expected that a higher dose would reach 70%. Even 50 mg/kg (+)-methamidophos could cause

behavioral deficits and some lesions in the spinal cord, evidence that OPIDN may occur even when NTE is not 70% inhibited (Ehrich et al., 1995). OPIDN follows NTE inhibition and aging of OP-inhibited enzyme, but aging was not measured in this study. Others have suggested that aging is slower and/or less intense for methamidophos than for TOCP (Vilanova et al., 1987, Johnson et al., 1989, Sogorb et al., 1997 and Kellner et al., 2000). In addition to being measured shortly after dosing, NTE activity was also measured at time of sacrifice, 21 days after OP dosing. At that time NTE inhibition was no longer inhibited, suggesting that the enzyme had been resynthesized (Glynn, 2006). All enantiomers Pirfenidone mw of methamidophos dosed tuclazepam at 50 mg/kg

could cause 80% inhibition of AChE when measured 24 h after dosing. This contrasts with the 20% inhibition of AChE seen after TOCP. These results suggest that the great AChE inhibition that followed (±)- and (−)-methamidophos would not allow inhibition and aging of more than 70% of NTE and survival of the hens for 21 days. Sogorb et al. (2010) suggested that if the IC50NTE/IC50AChE ratio is greater than five, then the compounds would not be able to induce the neuropathy because the concentrations necessary for NTE inhibition and aging would not be compatible with the ability of individuals to survive with a strong acute cholinergic crisis. An IC50NTE/IC50AChE ratio less than five would suggest that the OP may be a neuropathic compound if it has the ability to induce the “aging” reaction. Calculating % of NTE inhibition/% of AChE inhibition ratio for each compound tested in the present study provides ratios of 4.4 and 0.7 for TOCP and (+)-methamidophos, respectively. For (±)- and (−)-methamidophos the ratios are both 0.2. Our results allow us to say that the enantiomer responsible for delayed effects is the (+)-methamidophos and the three isoforms of methamidophos generate similar acute effects in hens. In the present experiments calpain activity was measured because OPIDN develops a Wallerian-type axonal degeneration and this protease has been implicated in this process (El-Fawal et al.

To obtain their complete sequences, the peptides were reduced and S-alkylated

with vinyl pyridine according to the method described by Henschen [13]. Each sample was dissolved in 1 mL of 6 M guanidine–HCl in 0.1 M tris–HCl, pH 8.6. To this solution 30 μL of 2-mercaptoethanol was added under nitrogen and the sample incubated at 50 °C for 4 h. After this, 40 μL of 4-vinylpyridine was added and the samples were incubated under nitrogen at 37 °C in the dark during 2 h. The samples were then desalted on a Vydac C4 column, using a gradient of 0–65% acetonitrile in 0.1% TFA www.selleckchem.com/products/XL184.html during 140 min and lyophilized. The S-pyridyl-ethylated peptides were dissolved in 200 μL of 8 M urea, and then diluted with 1.8 mL of 0.1 M ammonium bicarbonate (pH 7.9) and

digested at 37 °C with chymotrypsin (2%, w/w enzyme/substrate) for 3 h. The peptides produced by this digestion were separated by reverse phase HPLC on a Vydac C-18 column (4.6 mm × 250 mm, i.d.) (small pore) using an extended gradient of 0–50% acetonitrile in 0.1% trifluoroacetic acid for 180 min at a flow rate of 1 mL/min. HEK293 cell lines stably expressing human NaV1.1, 1.2, 1.3, 1.5 and 1.6 (generously donated by GlaxoSmithKline, Medicines Res. Centre, Gunnels Wood Rd., Stevenage, Herts SG1 2NY, UK) were cultured in modified Dulbecco’s medium supplemented with 10% fetal bovine serum as described [23]. NaV1.4-expressing cells were obtained by stably transfecting a plasmid containing the hNav1.4 construct Target Selective Inhibitor Library (a kind gift from Prof. Diana Conti-Camerino, University of Bari, Italy). NaV1.7-expressing cells were obtained by transient transfection of a plasmid containing the hNaV1.7 construct (a kind gift from Prof. Franz Hofmann through Prof. Akihiko Casein kinase 1 Wada, University of Miyazaki, Japan). Approximately 2 × 104 cells were transfected with 2 μg of hNaV1.7 vector along with 0.2 μg of green fluorescent protein (GFP) in pEGFP-C1 (Clontech, USA) using lipofectamine reagent kit

(Invitrogen, USA) following the instructions of the manufacturer. Currents were recorded 24–72 h following transfection. The standard extracellular solution contained (mM): NaCl 70, N-Methyl-d-Glucamine 67, CaCl2 1, MgCl2 1.5, HEPES 5, d-glucose 10 at pH 7.40. The standard pipette solution contained (mM): CsF 105, CsCl 27, NaCl 5, MgCl2 2, EGTA 10, Hepes 10 at pH 7.30. About 6–8% of the cells in the clone expressing NaV1.6 channels had a persistent Na+ current, as reported by Burbidge et al. [7]. We systematically tested these cells and discarded those showing incomplete inactivation (a residual current after 250 ms of <0.1% of the peak Na+ current). Known quantities of the toxins were dissolved in the extracellular solution immediately before the experiments. Tetrodotoxin (TTX, Sigma, Italy) was used at 300 nM on the NaV1.1, 1.2, 1.3, 1.4, 1.6 and NaV1.7 currents and the resulting traces were subtracted from the control traces to obtain the TTX-sensitive currents; the NaV1.

aureus prevalence in a multivariate model (P < 0.0001, 0.02, 0.04, 0.03, 0.03 respectively) ( Supplementary Table 1). To investigate S. aureus loss and (re-)acquisition, the 360 individuals positive at recruitment (recruitment-positive) plus a further 211 S. aureus negative at recruitment (82 from the last general practice, 129 students, see Methods) were followed for a median (IQR) 2.0 (1.8–2.2) years, returning a median (IQR) 14 11, 12, 13, 14 and 15 swabs (range 1–20). Three (0.5%) individuals died and 121 (21%) were lost to follow-up (25 (4%) did not return any swabs post-baseline, 53 (9%) missed returning three consecutive swabs and were removed from follow-up and 43 (8%)

moved from the area or withdrew find more from the study) ( Fig. 1, Supplementary Fig. 1). S. aureus grew from 3749 of 7009 post-recruitment swabs returned (53%) and was subsequently recovered from 73 (35%) individuals S. aureus negative at recruitment (recruitment-negatives), ten (5%) at the first swab after recruitment. All S. aureus were spa-typed; of the 297 spa-types observed, 197 (66%) were only seen in one individual. The 297 spa-types formed 157 groups with ≤2 differences, 82 were singletons and 22 could not be grouped because they were too short ( Supplementary Table 2). Based on the carrier index (proportion of S. aureus positive swabs/swabs returned), just under half of the recruitment-positives carried

S. aureus Everolimus clinical trial consistently throughout the study, and just over 60% of recruitment-negatives never carried S. aureus ( Fig. 2). However, most of those with intermediate carrier indices had distinct phases of carriage of specific

selleck inhibitor spa-types and phases of non-carriage. In particular, recruitment-positives lost carriage at similar rates throughout the study, leading to approximately equal numbers with carrier indices below one. We therefore estimated the time course over which recruitment-negatives became positive and recruitment-positives gained a new spa-type (“gain”, Fig. 3), and over which recruitment-positives became negative and recruitment-negatives who had become positive then lost carriage (“loss”, Fig. 4). 162 (30%) of 544 participants returning ≥2 post-recruitment swabs acquired a new spa-type (with >2 differences) during follow-up, at a rate of 1.5% (95% CI 1.3–1.8%) per month. MRSA (EMRSA-15) was acquired by one individual. Similar percentages of recruitment-positives (29%) and recruitment-negatives (32%) acquired a new spa-type, and acquisition rates were similar (1.4% (95% CI 1.2–1.7%) and 1.8% (1.4–2.3%) per month respectively; log-rank P = 0.13, Fig. 3). There was no suggestion that acquisition rates plateaued over time ( Fig. 3). Age was the strongest recruitment factor associated with rate of acquisition, which was faster in younger individuals (adjusted P = 0.01) ( Table 1, Supplementary Table 2). Acquisition rates also varied independently with recruitment CC (global adjusted P = 0.

The corresponding commutation superoperators Hˆˆn(C) can be written as differences between left-side and right-side product superoperators Hˆˆn(L) and Hˆˆn(R), defined by their action on a density operator ρˆ: equation(3) Hˆˆ(C)=∑nHˆˆn(C)=∑nHˆˆn(L)-Hˆˆn(R)Hˆˆn(C)ρˆ=[Hˆn,ρˆ]=Hˆnρˆ-ρˆHˆnHˆˆn(L)ρˆ=HˆnρˆHˆˆn(R)ρˆ=ρˆHˆn Their faithful

representations have exponential dimensions, but representations in low correlation order basis sets are cheap [13]. In a given operator basis Oˆk: equation(4) Hˆˆn(L)jk=OˆjHˆˆn(L)Oˆk=TrOˆj†HˆnOˆk=Tr⊗m=1Nσˆj,m†⊗m=1Nσˆn,m⊗m=1Nσˆk,m Because dot products commute with direct products and the trace of a direct product is a product of traces, we have: equation(5) Hˆˆn(L)jk=Tr⊗m=1Nσˆj,m†σˆn,mσˆk,m=∏m=1NTrσˆj,m†σˆn,mσˆk,min which the dimension AZD0530 price of individual matrices σˆn,k is tiny and does not depend on the buy PD0332991 size of the spin system;

the computational complexity of computing Tr[σˆj,m†σˆn,mσˆk,m] is therefore O(1) and the complexity of computing one matrix element is O(N) multiplications, where N is the total number of spins in the system. With O(N2) interactions in the spin system, this puts the worst-case complexity of building the representation of the Hamiltonian in Eq. (3) to O(N3D2), where D is the dimension of the reduced basis set. The sparsity of spin Hamiltonians [19] and the fact that spin interaction networks in proteins are also sparse Aldol condensation puts the practically observed scaling closer to O(N2D) – a significant improvement on the O(4N) best-case scaling of the adjoint direct product representation. This improvement is further amplified by the presence of unpopulated states even in the low correlation order subspace [8], by the existence of multiple independently evolving

subspaces [13], and by the fact that not all of the populated states belong to the propagator group orbit of the detection state [11]. Matrix dimension, storage and CPU time statistics for a 512 × 512 point 1H–1H NOESY simulation of ubiquitin (573 protons, ∼50,000 terms in the dipolar Hamiltonian) are given in Table 2. As demonstrated in Fig. 1 and Fig. 2, the simulation is in good agreement with the experimental data. The state space restriction approximation reduces the Hamiltonian superoperator dimension from 4573 ≈ 10345 to 848,530. The reduced Hamiltonian is still sparse, and therefore within reach of modern matrix manipulation techniques – the simulation shown in Fig. 1 took less than 24 h on a large shared-memory computer.

LA was efficient to restore the normal levels of PAP-SF and to decrease DPPIV-SF activity of envenomed mice to lower levels than the controls, whereas SA was efficient to restore the normal levels

of APN-SF. Both LA and SA were also able to mitigate the effect of the LD50 of vBj on APB activity, but they did not alter the effect of this dose of venom on the PIP-SF in the renal cortex. Table 4 also shows that the protein content of MF of the renal cortex decreased under the action of LD50 of vBj. The level of DPPIV-MF activity was not affected, but all other AP under study in the MF of the renal cortex were susceptible to this dose of vBj, that selleckchem is: APA and CAP increased, and APN-MF, PIP-MF and PAP-MF decreased compared with controls. SA abolished the effect of LD50 of vBj on APN-MF and both SA and LA were able to mitigate the

effect of this dose of vBj on the levels of APA-MF and CAP-MF in the renal cortex. However, both drugs were unable to alter the effects of LD50 of vBj on the protein content of MF and on the activity levels of PIP-MF and PAP-MF in the renal cortex of envenomed mice. Furthermore, the association of these drugs with the LD50 of vBj promoted a significant decrease in DPPIV-MF activity in the renal cortex. Table 5 shows that the protein content in the SF of the renal medulla was not affected by the LD50 of Selleck Regorafenib vBj, as occurred in this same fraction of the renal cortex. However, similarly to the pattern that occurred in the SF of the renal cortex, all AP activities under study in the SF of the renal medulla were susceptible to this dose of vBj, that is: APB and DPPIV-SF increased, and APN-SF, PIP-SF and PAP-SF decreased in relation to the controls. LA was efficient to mitigate the

effects of vBj on the activities of Endonuclease APB and PAP-SF. LA and SA were efficient to restore the normal levels of DPPIV-SF, but they did not alter the effect of the LD50 of vBj on APN-SF and PIP-SF activities in the renal medulla. Table 5 also shows that the protein content in the MF of the renal medulla decreased under the action of the LD50 of vBj, as occurred in the MF of the renal cortex ( Table 4). In the renal medulla, the levels of APN-MF and DPPIV-MF activities were not significantly affected, but all other AP activities under study in the MF of the renal medulla were susceptible to this dose of vBj, that is: APA increased, and PIP-MF, CAP and PAP-MF decreased in relation to the controls. Both drugs, LA and SA, were efficient only for restoring the normal levels of APA, but they did not alter the effects of the LD50 of vBj on the protein content in the MF and on the activities of PIP-MF, CAP and PAP-MF in the renal medulla. Both drugs also decreased the activity of DPPIV in the MF of the renal medulla when associated with the LD50 of vBj, as occurred in the MF of the renal cortex.

3 nM was calculated. Due to different Ki-values for both inhibitors, previously data has shown that concentration ratios giving similar 20S inhibition patterns for BSc2118 and bortezomib is 10:1 [27]. Thus, compilation of equally potent concentrations of both BSc2118 and bortezomib revealed that these inhibitors comparatively

inhibit growth of the 22 tumor cell lines analyzed. BSc2118 and BSc2118-FL MDV3100 induce both accumulation of polyubiquitin conjugates and apoptosis in a broad spectrum of cells, as has been exemplarily shown in C26 colon cancer cells. Efficiency of inhibitors in organisms is highly dependent on bioavailability, stability and reversibility of the compounds. BSc2118 is partially instable in liver microsomal fraction. Whereas Bortezomib is irreversible, binding of BSc2118 is reversible [36]. Proteasome inhibition induces compensatory De Novo synthesis of proteasomes [39]. Whereas reversible inhibition affects more proteasomes in cells positively correlating with exposition

time (binding-dissociation-rebinding), more stable inhibition rather acts like a pulse inhibition. This means that cells which are able to compensate proteasome inhibition via De Novo synthesis do survive, but cells that are incapable of doing so suffer ABT 199 from UPR stress and accumulation of oxidized proteins [40]. In this context, the majority of tumor cells are more sensible to proteasome inhibition than their parental cells [27]. In order to study possible therapeutic potentials of BSc2118, we studied BSc2118-mediated effects in a mouse model Cytidine deaminase of malignant melanoma. BSc2118 in experimental melanoma therapy revealed some unexpected findings. First of all, neither BSc2118 nor bortezomib injected i.p. had any effects on tumor growth or survival of B16F10 tumor bearing mice (data not shown). It is known that tumor tissue has its own milieu and drugs working well In Vitro might not be effective In Vivo due to the existence of the tumor matrix [41]. Therefore, the inhibitor was injected directly into the tumor. Comparison of proteasome inhibition profiles after both i.p. and i.t. injection

of BSc2118 revealed that BSc2118 completely inhibited proteasome activity after i.t. injection, which lasted for at least 24 h. This result prompted us to check the effects of BSc2118 on tumor growth when injected i.t. We obtained tumor growth retardation and complete remission with a survival for up to two months in 38.5% of mice receiving BSc2118 from all experimental groups. However, BSc2118 at 10 and 15 mg/kg induced local toxicity, suggesting that local levels of proteasome inhibition within the tissue should not exceed 80%. On the contrary, increased proteasome inhibition might be toxic as has been demonstrated for bortezomib in primates [42]. In humans the inhibition of 20S activity with bortezomib does not exceed 70% [43].

For the sample size calculations, we expected that the diagnostic performances of the different methods were similar. As a consequence, we designed our study as an equivalence study of alternative methods. Also, because the objective of each method was to identify tumor cells in samples obtained from the same patient, we tried to estimate differences in sensitivity and specificity between methods by comparisons within each patient. We assumed that when a EPZ015666 method had a sensitivity of 80% and a specificity of 80% to identify tumor cells, the 2 methods would be considered equivalent if they could be performed within 20%

of one another (range of equivalence of 0.80). Also, because about 75% of patients

were expected to have a final diagnosis of malignancy, the calculated sample size was 77, with a power of 90% and a 2-sided significance level of 5%. Data were analyzed by using SPSS 18.0 for Windows (SPSS Inc, Chicago, Ill). A total of 85 patients were eligible during the study period. Two patients were excluded due to refusal. Another 2 were omitted from the analysis because the intended procedures could not be completed because of poor cooperation. Therefore, the final analyses were performed Sirolimus datasheet for a total of 324 punctures from 81 consecutive patients. Baseline characteristics and the final diagnosis are summarized in Table 1. One patient whose result of EUS-FNA was atypical cells was found to have

chronic pancreatitis after surgery. Of 4 cases with negative cytopathology results, 1 patient was diagnosed with pancreatic endocrine tumor and Liothyronine Sodium another with metastatic renal cell carcinoma after surgery. The other 2 patients were finally diagnosed as having pancreatic cancer during follow-up. There were no procedure-related adverse events except for 2 patients who developed mild acute pancreatitis and improved with conservative treatment. The number of diagnostic samples (118 [72.8%] of 162 vs 95 (58.6%) of 162; P = .001), cellularity (OR 2.12; 95% CI, 1.37-3.30; P < .001), and bloodiness (OR 1.46; CI, 1.28-1.68; P < .001) were higher in S+ than in S- ( Table 2). No air-drying artifact was observed in either group. Also, S+ was superior to S- in terms of accuracy (85.2% vs 75.9%; P = .004) and sensitivity (82.4% vs 72.1%; P = .005), although specificity was similar (95.8% vs 100%; P = .999). Bloodiness was greater in RS than in AF (OR 1.16; CI, 1.03-1.30; P = .017), although the number of diagnostic samples (108 [66.7%] of 162 vs 105 [64.8%] of 162; P = .608), cellularity (OR 0.99; CI, 0.86-1.14; P = .870), and air-drying artifact (none for both; P = .999) were not different ( Table 3). There were no differences in accuracy (79.6% vs 81.5%; P = .582), sensitivity (75.7% vs 78.8%; P = .455), and specificity (100% vs 95.8%; P = .999) between RS and AF.

The higher lead levels in blood and calcified tissues observed in the F + Pb group compared with the other groups13 indicate higher availability of lead and higher incorporation of this metal into tissues when it is associated with F. Hypomineralization was shown starting from the very surface of enamel (i.e., AG-014699 in vitro no subsurface lesions), reflecting the condition of rat enamel during the final wave of mineralization at the maturation stage.20 The cavities have also

been described in the case of hypomineralized mouse enamel formed in the absence of the gene for kallikrein 4.21 The presence of cavities can be explained by the interaction between mechanical loading and the hypomineralized enamel. An improvement in motor activity in rats exposed to Pb22 and the reduced enamel hardness resultant from hypomineralization23 are consistent with a higher probability of brittle fracture and cavity formation in enamel. In this context, LY2109761 mouse it is important to note that cavities were demonstrated to be surrounded by hypomineralized enamel (Fig. 2e–f). In the literature, rodent enamel

fluorosis has been scored by means of a macroscopically applied shade guide, so as to measure increasing whiteness of the incisor buccal surface.24 In relation to ours, such scoring system, which was validated by quantitative light-induced fluorescence on the non-sectioned buccal surface, poses three major limitations: (i) it cannot be used to localize a single fluorotic lesion; (ii) the surface features are not related to inner histological ones, and (iii) the number of cavities is not taken into account. Spatially-resolved correlations between surface and internal enamel Smoothened defects might be helpful for a deeper understanding of the mechanism of enamel fluorosis. Rises in fluoride concentrations do not seem to be responsible for the appearance of the more severe defects in the F + Pb group, since no increased amounts of fluoride

could be detected in the calcified tissues of the animals co-exposed to lead. Furthermore, fluorosis severity has been shown to be influenced by a variety of factors, such as the genetic background in rats.24 The more severe defects observed in the F + Pb group would more likely be caused by an additive or synergistic effect of the co-exposure to fluoride and lead. Lead alone did not produce any alterations. Although it is known that lead concentration in calcified tissues is 2–3.4 times higher in the F + Pb group compared with the Pb group,13 these concentrations still would not elicit enamel defects in the absence of fluoride. Lead given to rats at 34 and 170 ppm in the drinking water for 70 days did not modify the superficial physical properties of mature enamel,10 even though enamel mineralization was delayed, and more protein was found in the secretory early maturation stage compared with controls.