Neurotoxic characteristics of spatial recognition damage of the hippocampus in mice following subchronic peroral exposure to TiO2 nanoparticles

Due to the increased application of titanium dioxide nanoparticles (TiO2 NPs) in various areas, numerous studies have been conducted which have confirmed that exposure to TiO2 NPs may result in neurological damage in both mice and rats. However, very few studies have focused on the molecular mechanisms of spatial recognition injury. In the present study, to understand the possible neurobiological responses of the mouse hippocampus following subchronic peroral exposure to low level TiO2 NPs, mice were exposed to 2.5, 5, and 10mg/kg body weight TiO2 NPs for 90 consecutive days. Hippocampal pathology and neuron ultrastructure, and long-term potentiation (LTP) were then evaluated, and the hippocampal mRNA-expression of several genes and their proteins involved in homeostasis of neuronal synaptic plasticity were investigated using a quantitative real-time PCR and ELISA method. We observed that subchronic peroral exposure to TiO2 NPs caused severe pathological changes, spatial recognition impairment, and resulted in significant LTP reduction and down-regulation of N-methyl-D-aspartate (NMDA) receptor subunits (NR2A and NR2B) expression associated with the simultaneous inhibition of CaMKIV, cyclic-AMP responsive element binding proteins (CREB-1, CREB-2), and FosB/DFosB in mouse hippocampal tissues. Therefore, our findings suggest that the application of TiO2 NPs in the various areas should be paid more attention.

Effect of intracerebroventricular injection of TiO2 nanoparticles on complex behaviour in the rat

There are no data available on the behavioural effects of centrally administered nanoparticles in freely moving intact mammals. Consequently, in the current study male Sprague-Dawley rats were trained to respond under an alternating-lever cyclic-ratio (ALCR) schedule of food reinforcement. Under this schedule, ascending and descending sequences of fixed-ratio (FR) lever press requirements for food reinforcement were presented over six cycles, with each discrete FR component completed on the alternate lever to the previous component. The final version of the schedule was comprised of an ascending followed by a descending sequence of the ratio values 2, 6, 12, 20, 30, 42 and 56, repeated over six cycles. When the rats were able to complete this version of the ALCR schedule in 40 min, each was implanted with a permanently indwelling ICV cannula aimed at the lateral ventricle of the brain, and allowed to recover for 7 days. On the first day of the experiment, all rats were injected with either titanium dioxide (TiO2, 9 nm, stabilised with gallic acid, 10 microl volume, 2 mg/ml) nanoparticles, or 10 microl saline (control). Two-hours after the ICV injections, the behaviour of all rats was measured using the ALCR schedule, and their behaviour was also measured (no ICV injection) for the next 7 days. Under the ALCR schedule, the number of lever-switching errors and incorrect lever perseverations significantly increased in the TiO2 group (p < 0.05). Other parameters of the ALCR schedule (RRRs and PRPs), which indicate the induction of malaise or general motor retardation, were not altered following ICV TiO2 injection. The findings of the current study indicate that central administration of TiO2 nanoparticles induced behavioural deterioration in freely moving intact animals, that the induced behavioural deterioration was a result of central rather than peripheral outcomes, and that this effect was chronic rather than acute.

Critical comparison of intravenous injection of TiO2 nanoparticles with waterborne and dietary exposures concludes minimal environmentally-relevant toxicity in juvenile rainbow trout Oncorhynchus mykiss

A critical comparison of studies that have investigated tissue accumulation and toxicity of TiO2-NPs in fish is necessary to resolve inconsistencies. The present study used identical TiO2-NPs, toxicological endpoints, and fish (juvenile rainbow trout Oncorhynchus mykiss) as previous studies that investigated waterborne and dietary toxicity of TiO2-NPs, and conducted a critical comparison of results after intravenous caudal-vein injection of 50 μg of TiO2-NPs and bulk TiO2. Injected TiO2-NPs accumulated only in kidney (94% of measured Ti) and to a lesser extent in spleen; and injected bulk TiO2 was found only in kidney. No toxicity of TiO2 was observed in kidney, spleen, or other tissues. Critical comparison of these data with previous studies indicates that dietary and waterborne exposures to TiO2-NPs do not lead to Ti accumulation in internal tissues, and previous reports of minor toxicity are inconsistent or attributable to respiratory distress resulting from gill occlusion during waterborne exposure.

Transcutaneous delivery of micro- and nanoparticles with laser microporation

Fractional laser ablation is one of the relatively safe and minimally invasive methods used to administer micro- and nanoparticles into the skin at sufficiently large depth. In this article, we present the results of delivery of TiO₂ nanoparticles and Al₂O₃ microparticles into skin. Fractional laser microablation of skin was provided by a system based on a pulsed Er:YAG laser with the following parameters: the wavelength 2940 nm, the pulse energy 3.0 J, and the pulse duration 20 ms. Ex vivo and in vivo human skin was used in the study. The suspensions of titanium dioxide and alumina powder in polyethylene glycol with particle size of about 100 nm and 27 μm, respectively, were used. In the ex vivo experiments, reflectance spectra of skin samples with administered particles were measured and histological sections of the samples were made. In the in vivo experiment, reflectance spectroscopy, optical coherence tomography, and clinical photography were used to monitor the skin status during one month after suspension administering. It is shown that particles can be delivered into dermis up to the depth 230 μm and distributed uniformly in the tissue. Spectral measurements confirm that the particles stay in the dermis longer than 1 month.

A patient with scirrhous stomach cancer treated with combination of hyperthermotherapy and 5-aminolevulinic acid (ALA)

A 35-year-old female with scirrhous stomach cancer (stage IV) was treated with a combination of 5-aminolevulinic acid (ALA), sodium dichloroacetate (DCA), hyperthermotherapy, and immunotherapy as terminal care. The patient survived for one year and seven months, during which her quality of life was markedly improved and she returned to work. The patient was diagnosed with poorly-differentiated adenocarcinoma and progressive signet-ring cell carcinoma, accompanied by left ovarian metastasis, peritoneal dissemination, and right hydronephrosis stage IV, and treated with combination chemotherapy with tegafur-gimeracil-oteracil potassium (TS-1) and docetaxel. Oral ALA and DCA were concomitantly administered at 50 mg each three times a day (150 mg/day, respectively). In addition, hyperthermotherapy using thermotron was concomitantly performed at 2- to 3-week intervals. Cellular immunotherapy with αβ T- and immature dendritic cells was also performed. The disease did not progress for 11 months, her quality of life was markedly improved, and she was able to return to work. However, the signs of enlargement of the ovarian metastatic lesion were noted later, for which chemotherapy with four cycles of second-line paclitaxel and a half dose of irinotecan and cisplatin as third-line treatment were performed. Combination of ALA/DCA, hyperthermotherapy, and cellular immunotherapy may be a low-invasive palliative therapy superior in maintaining quality of life of tumor-bearing terminally ill individuals.

In vivo caprine model for osteomyelitis and evaluation of biofilm-resistant intramedullary nails

Bone infection remains a formidable challenge to the medical field. The goal of the current study is to evaluate antibacterial coatings in vitro and to develop a large animal model to assess coated bone implants. A novel coating consisting of titanium oxide and siloxane polymer doped with silver was created by metal-organic methods. The coating was tested in vitro using rapid screening techniques to determine compositions which inhibited Staphylococcus aureus growth, while not affecting osteoblast viability. The coating was then applied to intramedullary nails and evaluated in vivo in a caprine model. In this pilot study, a fracture was created in the tibia of the goat, and Staphylococcus aureus was inoculated directly into the bone canal. The fractures were fixed by either coated (treated) or non-coated intramedullary nails (control) for 5 weeks. Clinical observations as well as microbiology, mechanical, radiology, and histology testing were used to compare the animals. The treated goat was able to walk using all four limbs after 5 weeks, while the control was unwilling to bear weight on the fixed leg. These results suggest the antimicrobial potential of the hybrid coating and the feasibility of the goat model for antimicrobial coated intramedullary implant evaluation.

Susceptibility of young and adult rats to the oral toxicity of titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) have potential applications as food additives, but concerns persist about their safety. Children are identified as having the highest exposure and may face the greatest health risks. However, the toxicological sensitivity of TiO2 NPs in different ages is not clear. Here, a comparative toxicity study of TiO2 NPs in 3-week (youth) and 8-week (adult) old Sprague-Dawley rats is reported following oral exposure at doses of 0, 10, 50, 200 mg kg(-1) body weight per day for 30 days. The organ mass and histology, blood biochemistry and redox state, intestinal function, and biodistribution of NPs are characterized. The results show that TiO2 NPs induce different toxic effects on young and adult rats. The liver edema, heart injuries and non-allergic mast cell activation in stomach tissues are found in young rats. On the other hand, only slight injury in the liver and kidney and decreased intestinal permeability and molybdenum contents are found in adult rats. Furthermore, TiO2 NP exposure can provoke reductive stress (i.e., increased reduced glutathione (GSH)/oxidized glutathione (GSSG) ratios) in plasmas through enhancing the glucose and GSH levels in young rats or reducing the glutathione peroxidase (GSH-Px) acitivity and GSSG levels in adult rats. These results suggest that different ages may require different biomarkers for identifying and monitoring oral toxicity of nanoparticles.

Whole-body nanoparticle aerosol inhalation exposures

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter < 200 nm and a geometric standard deviation σg < 2.5 (5). The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size (6), which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria (5). A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m(3) whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm(3)) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m(3)). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpre and Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is sampling flowrate (m(3)/min), and t is the sampling time (minute). The chamber pressure, temperature, relative humidity (RH), O2 and CO2 concentrations were monitored and controlled continuously. Nano-TiO2 aerosols collected on Nuclepore filters were analyzed with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. In summary, we report that the nano-particle aerosols generated and delivered to our exposure chamber have: 1) steady mass concentration; 2) homogenous composition free of contaminants; 3) stable particle size distributions with a count-median aerodynamic diameter of 157 nm during aerosol generation. This system reliably and repeatedly creates test atmospheres that simulate occupational, environmental or domestic ENM aerosol exposures.

[Long-term survival of metastatic clear cell adenocarcinoma of the female urethra by multidisciplinary treatment: a case report]

We report a case of clear cell adenocarcinoma of the female urethra. A 57-year-old woman presented with complaint of gross hematuria. Abdominal ultrasonography, cystourethroscopy, computed tomography (CT) and magnetic resonance imaging (MRI) revealed the urethral tumor was invasive to bladder neck. Clinical stage was determined as cT3N1M0, then anterior pelvic exenteration and ileal conduit formation were performed. The pathological diagnosis was clear cell adenocarcinoma of urethra and the stage was pT3N1. The patient received TS-1 and cisplatin for postoperative recurrence, but she died from multiple lung metastasis 54 months after the operation. Clear cell adenocarcinoma of the female urethra is rare case in the Japanese literatures. Pathogenesis and management of this rare condition are discussed.

Nanosized TiO2-induced reproductive system dysfunction and its mechanism in female mice

Recent studies have demonstrated nanosized titanium dioxide (nano-TiO2)-induced fertility reduction and ovary injury in animals. To better understand how nano-TiO2 act in mice, female mice were exposed to 2.5, 5, and 10 mg/kg nano-TiO2 by intragastric administration for 90 consecutive days; the ovary injuries, fertility, hormone levels, and inflammation-related or follicular atresia-related cytokine expression were investigated. The results showed that nano-TiO2 was deposited in the ovary, resulting in significant reduction of body weight, relative weight of ovary and fertility, alterations of hematological and serum parameters and sex hormone levels, atretic follicle increases, inflammation, and necrosis. Furthermore, nano-TiO2 exposure resulted in marked increases of insulin-like growth factor-binding protein 2, epidermal growth factor, tumor necrosis factor-α, tissue plasminogen activator, interleukin-1β, interleukin -6, Fas, and FasL expression, and significant decreases of insulin-like growth factor-1, luteinizing hormone receptor, inhibin α, and growth differentiation factor 9 expression in mouse ovary. These findings implied that fertility reduction and ovary injury of mice following exposure to nano-TiO2 may be associated with alteration of inflammation-related or follicular atresia-related cytokine expressions, and humans should take great caution when handling nano-TiO2.

A Phase I/II trial of radiotherapy concurrent with TS-1 plus cisplatin in patients with clinically resectable type 4 or large type 3 gastric cancer: Osaka Gastrointestinal Cancer Chemotherapy Study Group OGSG1205

A Phase I/II trial of radiotherapy administered concurrently with TS-1 plus cisplatin has been initiated in Japanese patients with clinical resectable type 4 or large type 3 gastric cancer. The aim of this trial is to determine the recommended dose of TS-1 and cisplatin combined with radiotherapy at a fixed dose in the Phase I study, and to evaluate the efficacy and safety in the Phase II study. The primary endpoint for Phase II is the pathological complete response rate, assessed using surgically resected specimens. Secondary endpoints are the response rate, progression-free survival, overall survival, operation transitional rate, R0 resection rate, rate of treatment completion, rate of down-staging and rates of postoperative complications and adverse events. In Phase II, a total of 30 patients will be enrolled in the Osaka Gastrointestinal Cancer Chemotherapy Study Group trial over a period of 6 years.

Daily sperm production: application in studies of prenatal exposure to nanoparticles in mice

We investigated the influence of maternal airway exposure to nanoparticulate titanium dioxide (TiO₂, UV-Titan) and carbon black (CB, Printex90), on male reproductive function in the two following generations. Time-mated C57BL/6J mice were exposed by inhalation to UV-Titan, or by intratracheal instillation with Printex90. Body and testicle weight, sperm content per g testicular parenchyma and daily sperm production (DSP) were assessed. The protocol for assessment of DSP was optimized for application in mice (C57BL/6J) and the influence of different parameters was studied. Maternal particulate exposure did not affect DSP statistically significantly in the F1 generation, although TiO₂ tended to reduce sperm counts. Overall, time-to-first F2 litter increased with decreasing sperm production. There was no effect on sperm production in the F2 generation originating after TiO₂ exposure. F2 offspring, whose fathers were prenatally exposed to Printex90, showed lowered sperm production. Furthermore, we report statistically significant differences in sperm production between mouse strains.

Biological response to nano-scale titanium dioxide (TiO2): role of particle dose, shape, and retention

Titanium dioxide (TiO2) is one of the most widely used nanomaterials, valued for its highly refractive, photocatalytic, and pigmenting properties. TiO2 is also classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen. The objectives of this study were to (1) establish a lowest-observed-effect level (LOEL) for nano-scale TiO2, (2) determine TiO2 uptake in the lungs, and (3) estimate toxicity based on physicochemical properties and retention in the lungs. In vivo lung toxicity of nano-scale TiO2 using varying forms of well-characterized, highly dispersed TiO2 was assessed. Anatase/rutile P25 spheres (TiO2-P25), pure anatase spheres (TiO2-A), and anatase nanobelts (TiO2-NB) were tested. To determine the effects of dose and particle characteristics, male Sprague-Dawley rats were administered TiO2 (0, 20, 70, or 200 μg) via intratracheal instillation. Bronchoalveolar lavage fluid (BALF) and lung tissue were obtained for analysis 1 and 7 d post exposure. Despite abundant TiO2 inclusions in all exposed animals, only TiO2-NB displayed any significant degree of inflammation seen in BALF at the 1-d time point. This inflammation resolved by 7 d, although TiO2 particles had not cleared from alveolar macrophages recovered from the lung. Histological examination showed TiO2-NB produced cellular changes at d 1 that were still evident at d 7. Data indicate TiO2-NB is the most inflammatory with a LOEL of 200 μg at 1 d post instillation.

BmNPV resistance of silkworm larvae resulting from the ingestion of TiO₂ nanoparticles

Bombyx mori nucleopolyhedrovirus (BmNPV) causes infection in the silkworm that is often lethal. The infection is hard to prevent, partly because of the nature of the virus particles and partly because of the different strains of B. mori. Titanium dioxide nanoparticles (TiO₂ NPs) have been demonstrated to have antimicrobial properties. The present study investigated whether TiO₂ NPs added to an artificial diet can increase the resistance of B. mori larvae to BmNPV and examined the molecular mechanism behind any resistance shown. The results indicated that ingested TiO₂ NPs decreased reactive oxygen species and NO accumulation in B. mori larvae under BmNPV infection, which in turn led to a decrease in their growth inhibition and mortality. In addition, the TiO₂ NPs significantly promoted the expression of resistance-related genes, including those encoding superoxide dismutase, catalase, glutathione peroxidase, acetylcholine esterase, carboxylesterase, heat shock protein 21, glutathione S transferase o1, P53, and transferring and of genes encoding cytochrome p302 and nitric oxide synthase. These findings are a useful addition to the understanding of the mechanism of BmNPV resistance of B. mori larvae in response to TiO₂ NPs addition. Such information also provides a theoretical basis for the use of TiO₂ NPs in sericulture.

Photoinduced disaggregation of TiO₂ nanoparticles enables transdermal penetration

Under many aqueous conditions, metal oxide nanoparticles attract other nanoparticles and grow into fractal aggregates as the result of a balance between electrostatic and Van Der Waals interactions. Although particle coagulation has been studied for over a century, the effect of light on the state of aggregation is not well understood. Since nanoparticle mobility and toxicity have been shown to be a function of aggregate size, and generally increase as size decreases, photo-induced disaggregation may have significant effects. We show that ambient light and other light sources can partially disaggregate nanoparticles from the aggregates and increase the dermal transport of nanoparticles, such that small nanoparticle clusters can readily diffuse into and through the dermal profile, likely via the interstitial spaces. The discovery of photoinduced disaggregation presents a new phenomenon that has not been previously reported or considered in coagulation theory or transdermal toxicological paradigms. Our results show that after just a few minutes of light, the hydrodynamic diameter of TiO₂ aggregates is reduced from ∼280 nm to ∼230 nm. We exposed pigskin to the nanoparticle suspension and found 200 mg kg⁻¹ of TiO₂ for skin that was exposed to nanoparticles in the presence of natural sunlight and only 75 mg kg⁻¹ for skin exposed to dark conditions, indicating the influence of light on NP penetration. These results suggest that photoinduced disaggregation may have important health implications.

Oxidative stress and antioxidant responses of liver and kidney tissue after implantation of titanium or titanium oxide coated plate in rat tibiae

Coating with titanium oxides is a promising method to improve the blood compatibility of materials to be used for medical implants. However, biodegradation of the coating can result in microparticles that subsequently cause oxidative stress. Therefore, the present study was carried out to throw some light on the mechanisms affecting the reaction of tissue surroundings Ti implants either in the form of titanium oxide or not in tibiae of rats. The serum collected twice from animals during the period of study and rats were sacrificed after two months of implantation. The complete blood picture, total proteins content and the activities of some serum enzymes were determined as liver biomarker. Kidney function was examined by measuring the levels of serum creatinine and uric acid. The level of lipid peroxidation and the activities of superoxide dismutase, catalase and glutathione S-transferase as well as glutathione content in liver and kidney tissue were evaluated. It has been indicated that the lipid peroxidation is one of the molecular mechanisms involved in Ti-plate induced cytotoxicity however; the TiO(2)-plate did not. The biodegradation of Ti-plate was very slow that could explain why the all enzymatic and non-enzymatic antioxidant not affected by implantation of Ti-plate. The total antioxidant level in serum was better in rats had TiO(2)/Ti-plate than those animals that had Ti-plate. The coating of titanium implants with titanium oxide leads to attaining of reduced the oxidative state in the cells, which enhance the healing process in comparison with the uncoated implants.

Effects of aged TiO2 nanomaterial from sunscreen on Daphnia magna exposed by dietary route

The toxicity of dietary exposure to artificially aged TiO(2) nanomaterial (T-Lite™) used in sunscreen cream was studied on D. magna. Pseudokirchneriella subcapitata cultures were contaminated with TiO(2)-residues, obtained by artificial aging. Significant association of TiO(2)-residues on algae was detected by X-ray fluorescence spectromicroscopy. A D. magna dietary chronic exposure of these contaminated algae with TiO(2)-residues was performed. X-ray chemical imaging revealed that Ti was localized only in the digestive tract of the daphnia. Chronic exposure of daphnia to by-product of aged TiO(2) nanoparticles brought by food induced low mortality but decreased growth and reproduction which can be partly related to the modification of the digestive physiology of daphnia. This study demonstrated that the assessment of the ecotoxicological impact of nanomaterials in aquatic environment should take into account the aging of these materials which can further influence their bioavailability for aquatic organisms.

Proteomic analysis of early response lymph node proteins in mice treated with titanium dioxide nanoparticles

Human exposure to nanoparticles is inevitable from natural and anthropogenic sources. Titanium dioxide (TiO2) nanoparticles are increasingly being used in pharmaceutical and cosmetic products. Previous studies revealed that TiO2 levels were significantly increased in tissues (e.g., lymph nodes) after mice were injected with nanosized TiO2. To identify early response lymph node proteins to TiO2 nanoparticles, groups of mice were intradermally injected with a low dose of DeGussa P25 TiO2 nanoparticles or vehicle alone. The proteomes of lymph nodes at 24 h were quantitatively analyzed using trypsin-catalyzed 16O/18O labeling in conjunction with two-dimensional liquid chromatography separation and tandem mass spectrometry (2DLC-MS/MS). A total of 33 proteins were significantly changed (over 1.3-fold, p<0.05) in the mice treated with TiO2 nanoparticles, which accounted for approximately 1% of the total proteins identified. The differentially expressed proteins mainly involve the immune response (e.g., inflammation), lipid and fatty acid metabolism, mRNA processing, and nucleosome assembly. Regulation of functionally distinct classes of proteins could be mediated by estrogen receptor (ESR1), PPARγ, and c-Myc signalings, etc. The differentially expressed proteins identified in this experiment could represent early response proteins to TiO2 nanoparticle treatment in mouse lymph nodes.

Titanium-nitride-oxide-coated Titan-2 bioactive coronary stent: a new breakthrough in interventional cardiology

The introduction of drug-eluting stents (DES) has revolutionized the field of interventional cardiology, since it has reduced the incidence of restenosis by 50% to 70%. However, recent worrisome data from registries and meta-analyses emphasized higher rates of late and very late stent thrombosis associated with DES. The recently introduced titanium-nitride-oxide-coated stent bioactive stent (Titan-2) was manufactured by a proprietary process to coat titanium-nitride-oxide on the surface of the stainless steel stent, based on a plasma technology using the nano-synthesis of gas and metal. This late-breaking stent has demonstrated an excellent biocompatibility, as reflected by lower rates of platelet aggregation and fibrin deposition, and better endothelialization. Preclinical and clinical trials and registries involving real-life unselected populations have shown a low rate of major adverse cardiac events at long-term follow-up. Restenosis rates were comparable with those of DES, with very rare stent thrombosis. Equally favorable results have been obtained in patients at high-risk of in-stent restenosis, such as diabetics and those with small coronary arteries. Results in patients presenting with acute coronary syndrome have been again comparable to those of DES, with tendency to lower rates of myocardial infarction and stent thrombosis. Comparisons with second generation drug-eluting stents have also been promising.

Nanotechnology in cosmetic products

Nanotechnology is a subject of extensive global interest. The ability to control matter at the nanoscale level presents a revolutionary opportunity to benefit society in numerous disciplines. Nanotechnology is currently found in cosmetic products, particularly sunscreen products containing titanium dioxide and zinc oxide. Published information in scientific journals suggests that nano-sized ingredients used in cosmetic products pose no more risk to human health than larger sized counterparts. The issue remains under investigation.

The acute and long-term effects of Middle East sand particles on the rat airway following a single intratracheal instillation

Military personnel deployed in the Middle East have emphasized concerns regarding high levels of dust generated from blowing desert sand and the movement of troops and equipment. Airborne particulate matter levels (PM(10); PM < 10 μm) in the region may exceed 1500 μg/m(3), significantly higher than the military exposure guideline (MEG) of 50 μg/m(3). Increases in PM(10) have been linked to a rise in incidences of asthma, obstructive pulmonary disease, lung cancer, and cardiovascular diseases. Male Sprague-Dawley rats received a single intratracheal (IT) instillation of 1, 5, or 10 mg of Middle East PM(10) collected at a military occupied site in Kuwait, silica (positive control), or titanium dioxide (TiO(2); negative control) suspended in 400 μl sterile saline, or saline alone (vehicle control). Twenty-four hours, 3 d, 7 d and 6 mo postexposure (n = 15/group), organs including lung were evaluated for histopathological changes and for particle contaminants. Bronchoalveolar fluid (BALF) was also analyzed for cellular and biochemical parameters, including cytokines and chemokines. Instillation of silica resulted in early, pronounced, sustained inflammation indicated by significant increases in levels of total protein and neutrophils, and activities of lactate dehydrogenase activity and β-glucuronidase activity. Lower magnitude and transient changes using the same markers were observed in animals exposed to TiO(2) and Middle East PM(10). The results suggest that for acute exposures, this Middle East PM(10) is a nuisance-type dust with relatively low toxicity. However, since average deployment of military personnel to the Middle East is 180 d with potential for multiple follow-on tours, chronic exposure studies are needed to fully understand the pulmonary effects associated with Middle East PM exposure.

Tio2-dopamine complex implanted unilaterally in the caudate nucleus improves motor activity and behavior function of rats with induced hemiparkinsonism

Parkinson's disease (PD) is characterized by malfunction of dopaminergic systems, and the current symptomatic treatment is to replace lost dopamine. For investigating mechanisms of pathogenesis and alternative treatments to compensate lack of dopamine (DA) activity in PD, the 6-hydroxydopamine (6-OHDA)-lesioned rat model of PD has been useful, these animals display apomorphine-induced contralateral rotational behavior, when they are examined after lesion. The purpose of this study was to assess Titania-dopamine (TiO2-DA) complexes implanted on the caudate nucleus for diminishing motor behavior alterations of the 6-OHDA rat model. Rats with 6-OHDA unilateral lesions received TiO2 alone or TiO2-DA implants, and were tested for open field (OF) gross motor crossing and rearing behaviors, and apomorphine-induced rotation (G) behavior. TiO2 complex have no effects on rearing OF and G behaviors, and a significant reducing effect on crossing motor behavior of normal rats compared to control non-treated rats throughout 56 days of observation. Interestingly, TiO2-DA treatment significant recovered motor crossing and rearing behaviors in 6-OHDA-lesioned rats, and diminished the G behaviors during 56 days of examination. Additionally, in the 6-OHDA-lesioned rats TiO2 treatment had a moderate recovering effect only on crossing behavior compared to lesioned non treated rats. Our results suggest that continuous release of dopamine in the caudate nucleus from TiO2-DA complex is capable of reversing gross motor deficits observed in the 6-OHDA-lesioned rat model of PD. Thistype of delivery system of DA represents a promising therapy for PD in humans.

Dose dependent in vivo metabolic characteristics of titanium dioxide nanoparticles

Nanoparticle in vivo characteristics and interactions between nanoparticles and organisms are key components of nanotoxicology. 1H NMR was used to analyze rat urine metabolites exposed to TiO, nanopartcles by intratracheal instillation in low (0.8 mg/kg), medium (4 mg/kg) and high doses (20 mg/kg). Significant metabolite (Acetate, Valine, Dimethylamine, Taurine, Hippurate, and 2-Oxoglutarate) changes were only observed in the low dose group. These compensatory changes resolve within seven days, and the results of serum biochemical assays also implied no parenchymal damages in the liver or kidney. Rats exposed to medium and high dose nanoparticles had pulmonary inflammation because most of the instilled particles aggregated into larger sizes and accumulated in lung tissue. We conclude that low dose instillation of nano-TiO, can recoverably impact metabolic function because the scattered nanoparticles can migrate from the lung to liver or kidney, but particles in higher doses will aggregate and deposit in the lung without migration.

Systematic influence induced by 3 nm titanium dioxide following intratracheal instillation of mice

This work reported the systematic influence of titanium dioxide nanoparticles (TiO2 NPs) with a diameter of 3 nm on mice. Mice were repeated intratracheally instilled with TiO2 NPs, once per-week for 4 consecutive weeks, at total dose of 13.2 mg/kg. At 28 days post-instillation, the biochemical parameters in broncboalveolar lavage fluid (BALF) and brain homogenate as well as histopathologic changes of tissues were examined to describe the subacute toxicity of instilled TiO2 NPs. The results showed that instilled TiO2 NPs could induce lung damage, and change the permeability of alveolar-capillary barrier. The TiO2 NPs were able to get access to blood circulation and reach extrapulmonary tissues, then lead to injury at the different level, such as liver and kidney. Our results also indicated that TiO2 NPs might pass through the blood-brain barrier (BBB), and induce the brain injury through oxidative stress response.