Quantum dots are time bomb: Multiscale toxicological study

The use of quantum dots has spread widely into many applications. Works on the study of quantum dots on living organisms have had conflicting results on toxicity. There are no full-scale long-term toxicological studies with multiple administration of quantum dots. Understanding the toxicity of quantum dots is still limited. Here we present data on the effects of quantum dots on animals. In this work for the first time, it is shown that at a single administration of quantum dots in the body they have moderate species-specific toxicity, but repeated administration of quantum dots for 14 days even in the amount of 0.5 mg/kg leads to a delayed not completely irreversible hematotoxic effect, delayed irreversible disorders of barrier function of the liver, irreversible nephrotoxic effect, and to pathological changes in the thymus, kidneys and spleen. Administration of quantum dots in the amount of 2.5 mg/kg for 14 days leads to irreversible changes in the lungs, liver, spleen, kidneys and thyroid gland. This phenomenon is based on immunological reactions. On the one hand, these data confirm that quantum dots at a single administration can show relatively low toxicity. On the other hand, they cause to a delayed irreversible organ and tissue damage when repeatedly administered to the body even in small quantities. This study demonstrates that quantum dots are not as low in toxicity as previously thought to be and pose a serious risk when entering living organisms. Detecting and treating poisoning using standard methods of diagnosis and treatment of heavy metal poisoning may not be effective. This study demonstrates that toxic effects of quantum dots on a living body are quite complex and cannot be generalized based on previously reported assumptions.

The changes of hepatic bile acid synthesis and transport and bile acids profiles in isopsoralen-induced liver injury C57BL/6J mice

CONTEST

Isopsoralen, one of the main active and quality-control compounds in Psoralea corylifolia L. (Fabaceae), has antitumor and oestrogen-like effects. Previous studies demonstrated that isopsoralen induced hepatotoxicity and its long-term exposure led to cholestatic liver injury.

OBJECTIVE

This study investigates the effect of three- or seven-day exposure of low dose isopsoralen (80 mg/kg) on bile acid homeostasis in C57BL/6J mice.

MATERIALS AND METHODS

Forty-two C57BL/6J mice were randomly divided into control, three- and seven-day groups (n = 14 per group, half female and half male). Isopsoralen suspension was administrated intragastrically at 80 mg/kg once a day. Blood and liver samples were collected to measure biochemical indices and transport of BAs. The histopathology of the liver was also observed. HPLC-MS/MS was also used to measure the BAs profiles and transport activity.

RESULTS

In the study, isopsoralen increased the levels of serum AST, ALT in three- and seven-day groups, and caused vacuolar degeneration and swelling in the liver. Canalicular efflux transporters BSEP, OSTα, MRP2, MRP3, and basolateral uptake transporters NTCP, OATP4 were inhibited after seven-day-administration. Moreover, amino acid binding enzymes (BAAT and BACS) were also inhibited after seven-day-administration. The composition of BAs changed greatly and the concentration of some unconjugated-BAs which have stronger hydrophobicity, such as CA, CDCA, was significantly increased.

CONCLUSIONS

Isopsoralen (80 mg/kg) caused hepatotoxicity after short-term exposure by inhibiting the expression of efflux transporters, amino acid binding enzymes, and disrupting BAs spectrum.

Linking molecular targets of Cd in the bloodstream to organ-based adverse health effects

The chronic exposure of human populations to toxic metals remains a global public health concern. Although chronic Cd exposure is linked to kidney damage, osteoporosis and cancer, the underlying biomolecular mechanisms remain incompletely understood. Since other diseases could also be causally linked to chronic Cd exposure, a systems toxicology-based approach is needed to gain new insight into the underlying exposure-disease relationship. This approach requires one to integrate the cascade of dynamic bioinorganic chemistry events that unfold in the bloodstream after Cd enters with toxicological events that unfold in target organs over time. To this end, we have conducted a systematic literature search to identify all molecular targets of Cd in plasma and in red blood cells (RBCs). Based on this information it is impossible to describe the metabolism of Cd and the toxicological relevance of it binding to molecular targets in/on RBCs is elusive. Perhaps most importantly, the role that peptides, amino acids and inorganic ions, including HCO₃^-, Cl^- and HSeO₃^- play in terms of mediating the translocation of Cd to target organs and its detoxification is poorly understood. Causally linking human exposure to this metal with diseases requires a much better integration of the bioinorganic chemistry of Cd that unfolds in the bloodstream with target organs. This from a public health point of view important goal will require collaborations between scientists from different disciplines to untangle the complex mechanisms which causally link Cd exposure to disease.

Long-Term Effects of Unmodified 50 nm ZnO in Mice

Nanometer zinc oxide (nano-ZnO) is widely used in many kinds of fields. However, information about the toxicity and toxic mechanism of nano-ZnO is limited. The aims of this study were to investigate the long-term toxic effects of unmodified 50 nm ZnO administered by gavage in mice. After 90 days, hematological parameters, hepatic and renal functions, and oxidative and anti-oxidative status were measured. Pathological damages in livers, kidneys, and other tissues were also examined by hematoxylin and eosin (H&E) staining. The results showed that oral nano-ZnO exposure induced anemia and damages to liver and kidney, influenced the antioxidant system, and impacted functions of liver and kidney in mice after a 90-day exposure. The main cause for oxidative stress in vivo induced by nano-ZnO might be hydroxyl free radical. The lowest observed adverse effect level (LOAEL) was 40 mg/kg·bw, and the livers, kidneys, lungs, pancreas, and gastrointestinal tracts are the target organs.

The interplay between risk and preventive factors explains why some children develop allergies to certain foods and others show tolerance

AIM

A number of studies have clarified the tolerance mechanisms and risk factors for food allergies. Our aim was to explore food allergy symptoms by target organs, together with the risk factors and how to prevent food allergies and induce tolerance.

METHODS

We carried out a thorough review of studies on paediatric food allergies published in the last decade.

RESULTS

Food allergy symptoms may affect the skin, nasal and oral mucosa, conjunctivae, gastrointestinal tract or, in severe cases, the respiratory tract and cardiovascular organs. Immunoglobulin E (IgE)-mediated symptoms appear rapidly after exposure to the offending allergen, whereas non-IgE-mediated symptoms are typically delayed. The immunological processes involved in non-IgE-mediated allergic reactions are poorly understood, but T-cell activation is probably involved. There are several factors that influence the food sensitisation process: genetic predisposition, disruption of oral tolerance development, impaired skin barriers in atopic eczema and the influence of microbiomes.

CONCLUSION

The symptoms and intensity of reactions vary considerably with regard to food allergies, and these depend on the individual's concomitant immunological and regulatory mechanisms. There is strong evidence that dietary diversity is important for children, even when they come from families with high allergy risks.

Clinical and Morphological Aspects in Assessing the Safety of OSPL-502 with Repeated Dose Administration

BACKGROUND

OSPL-502 is a new potential medicinal drug which stimulates a cognitive function. It is necessary to reveal clinical manifestations of its general toxic effect and determine organs that are most heavily affected by this pharmacological substance.

AIMS

To describe and estimate clinical and histopathological changes in the organism of experimental animals in response to the repeated administration of pharmacological substance OSPL-502.

MATERIAL AND METHODS

The study was conducted by the OECD Guidelines (Test No. 407) on Sprague-Dawley rats. The drug was administered at the dose of 20, 60 and 180 mg/kg.

RESULTS

The repeated doses of OSPL-502 have not caused any toxic effects on the growth of body weight, food and water consumption of the tested animals, or affected the musculoskeletal system and exploratory behaviour of the rats in the doses of 20 and 60 mg/kg. The dose of 180 mg/kg (1800 times larger than the therapeutic dose) has shown clinical signs of toxicity in females but has not resulted in the death of the animals. Due to morphological methods, we have found histostructural changes in the liver, kidneys and adrenal glands of the rats that were treated with the test substance in the maximum dose. These changes are reversible and reduce within 14 days after the admission of the studied substances is cancelled.

CONCLUSION

OSPL-502 at the dose of 180 mg/kg has a weakly pronounced toxic effect, the dose of 60 mg/kg is the threshold, and that of 20 mg/kg is no-observable-adverse-effect-level (NOAEL); the liver, kidneys and adrenal glands can be considered target-organs for the tested substance.

Acute and Cumulative Effects of Unmodified 50-nm Nano-ZnO on Mice

Nanometer zinc oxide (nano-ZnO) is widely used in diverse industrial and agricultural fields. Due to the extensive contact humans have with these particles, it is crucial to understand the potential effects that nano-ZnO have on human health. Currently, information related to the toxicity and mechanisms of nano-ZnO is limited. The aim of the present study was to investigate acute and cumulative toxic effects of 50-nm unmodified ZnO in mice. This investigation will seek to establish median lethal dose (LD50), a cumulative coefficient, and target organs. The acute and cumulative toxicity was investigated by Karber's method and via a dose-increasing method, respectively. During the experiment, clinical signs, mortality, body weights, hematology, serum biochemistry, gross pathology, organ weight, and histopathology were examined. The LD50 was 5177-mg/kg·bw; the 95% confidence limits for the LD50 were 5116-5238-mg/kg·bw. It could be concluded that the liver, kidney, lung, and gastrointestinal tract were target organs for the 50-nm nano-ZnO acute oral treatment. The cumulative coefficient (K) was 1.9 which indicated that the cumulative toxicity was apparent. The results also indicated that the liver, kidney, lung, and pancrea were target organs for 50-nm nano-ZnO cumulative oral exposure and might be target organs for subchronic and chronic toxicity of oral administered 50-nm ZnO.

Assessing trace elements in striped dolphins from the Strait of Gibraltar: Clues to link the bioaccumulation in the westernmost Mediterranean Sea area and nearest Atlantic Ocean

Dolphins are considered sentinel species in the marine environment. The Strait of Gibraltar is the only passage between the Mediterranean Sea and the Atlantic Ocean, being the transitional region which connects these two basins and one of the most important routes of cetacean migration worldwide. In this work, eight trace elements (TE) were studied in 45 samples of liver, kidney and muscle, from 15 specimens stranded in this study area. The preliminary results show, among others, the patterns of distribution of the TE in the target organs studied, the influence of sex, length and developmental stage in these TE concentrations and the Se/Hg ratio. Subsequently, the results of TE concentrations in liver have being compared to previous data on S. coeruleoalba from the westernmost Mediterranean Sea and the nearest Atlantic Ocean. For some elements (e.g. for As), concentrations are similar to those obtained from Atlantic samples, despite in other cases (e.g. for Cd) results are lined up with those observed in Mediterranean studies. In addition, in the case of some TE (e.g. Se and Zn) the results are in the middle of those reported for both basins, reinforcing the idea of the Strait of Gibraltar being a transitional zone. Present study is the first research regarding this issue in this outstanding region, aiming to give insights of how this matchless area can help to link TE concentrations observed in these Atlantic and Mediterranean threatened species.

Target organ profiles in toxicity studies supporting human dosing: Does severity progress with longer duration of exposure?

We have previously reported the profile of target organs (defined as organs showing histopathological changes) in rodent and non-rodent toxicity studies conducted prior to first-time-in-man (FTiM) for 77 AstraZeneca candidate drugs (CDs). Here, we test the assumption that toxicity is exacerbated by dosing duration by comparing the incidence and severity of target organ toxicities in these ≤ 6 week FTiM studies with those observed in subsequent subchronic/chronic (≥ 3 month) studies. Looking at the effect of dosing duration on severity (pathological score) and incidence (percentage of animals within the group) for the 39 CDs that met the criteria for inclusion (comparable doses between FTiM and subchronic/chronic studies), new toxicities appeared for 31 target organs but existing ones resolved for 29 target organs. Increased severity was more frequent for rodent (16 target organs) than for non-rodent (4 target organs). Most notable changes were a large increase in severity/incidence in liver and in non-rodent lung in contrast to a large decrease in severity and incidence for kidneys/ureter and for the non-rodent thymus. Overall this analysis shows that, even with continued exposure, target organ toxicities of CDs are as likely to show partial or complete recovery as they are to progress in severity.

Target organ damage in acute heart failure

Acute heart failure is a prognostic factor due to its high mortality during the acute phase and the increased frequency of medium to long-term adverse events. The pathophysiological mechanisms triggered during these exacerbations can persist after reaching clinical stability, remaining even after the acute episode has ended. A certain degree of neurohormonal activation, oxidative stress, apoptosis and inflammation (among other conditions) can therefore persist, resulting in organ damage, not just of the myocardium but likely the entire cardiovascular apparatus. This new insight into the persistence of harmful mechanisms that last beyond the exacerbations could be the start of a change in perspective for developing new therapeutic strategies that seek an overall control of hemodynamic and congestive changes that occur during acute decompensated heart failure and changes that remain after achieving clinical stability.

Target organ profiles in toxicity studies supporting human dosing: an assessment of recovery and chronic dosing

We have previously reported the profile of toxic effects with respect to target organs (defined as organs showing histopathological changes) observed in rodent and non-rodent toxicity studies conducted prior to first time in man (FTIM) for 77 AstraZeneca candidate drugs (CDs) across a range of therapy areas. The main objectives of the current study were twofold; to determine which target organs observed in the FTIM studies recovered after a dose free recovery period and to determine which additional target organs were observed in subsequent chronic (⩾3month) studies required to support longer term clinical dosing. The analysis showed that ⩾86% of findings in studies supporting FTIM either fully or partially resolved at the end of the recovery period, with profiles of recovery that were similar whether the CD progressed into man or not and across different therapy areas. Compared to observations in FTIM studies, chronic studies identified toxicities in an additional 39% of target organs. Overall these data demonstrate that chronic studies in both rodents and non-rodents provide valuable information for the risk assessment for longer term dosing in humans. In addition, the high levels of recovery demonstrated in this analysis suggest that inclusion of recovery assessments on FTIM studies should be on a case-by-case basis driven by a positive indication of need. This is in line with ICH non-clinical guidance that states that reversibility of severe nonclinical toxicities of potential clinic relevance should be assessed 'when appropriate', but that the evaluation can be based on a study of reversibility or on a scientific assessment.