RADT-08. A VOLUMETRIC ANALYSIS OF STEREOTACTIC RADIOSURGERY LOW DOSE VOLUMES IN PREVENTING FUTURE BRAIN METASTASES

PURPOSE/OBJECTIVE(S) Stereotactic radiosurgery (SRS), compared to whole brain radiotherapy is limited in its ability to prevent development of brain metastases in untreated areas. The purpose of this study is to assess whether low-dose volumes delivered to uninvolved regions of the brain during SRS can reduce the risk of developing brain metastases in those regions. MATERIALS AND METHODS Data were collected for 69 patients with brain metastases who were treated with SRS at least two occasions. The regions of uninvolved brain receiving a high, intermediate, and low dose of incidental radiotherapy were defined as the volume receiving at least 10, 5, and 2.5 Gy if the prescribed dose was < 25 Gy (1-3 fraction plans) or the volume receiving at least 15, 7.5, and 5 Gy if the prescribed dose was ≥ 25 Gy (5 fraction plans). A second round metastasis was considered to occur within a given dose level if 20% or more of the tumor was found within that dose level. Probabilities were calculated based on the volume of each dose level as a percentage of total brain volume and were used to estimate the expected number of cases with at least one metastasis occurring in each dose level. RESULTS The average number of metastases treated in both rounds of SRS was two. The expected and observed number of cases with at least one second round metastasis were 0 and 2 for the high dose level (p=0.151), 7 and 3 for the intermediate dose level (p=0.018), and 17 and 11 for the low dose level (p=0.094). CONCLUSION We observed fewer than expected new metastases within prior SRS low dose levels based on volumetric probabilities, though this difference was only significant for the intermediate dose level. This suggests that low dose volumes from SRS may provide benefit in preventing future regional metastases.

Experimental safety testing shows that the NSAID tolfenamic acid is not toxic to Gyps vultures in India at concentrations likely to be encountered in cattle carcasses

Population declines of Gyps vultures across the Indian subcontinent were caused by unintentional poisoning by the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Subsequently, a number of other NSAIDs have been identified as toxic to vultures, while one, meloxicam, is safe at concentrations likely to be encountered by vultures in the wild. Other vulture-safe drugs need to be identified to reduce the use of those toxic to vultures. We report on safety-testing experiments on the NSAID tolfenamic acid on captive vultures of three Gyps species, all of which are susceptible to diclofenac poisoning. Firstly, we estimated the maximum level of exposure (MLE) of wild vultures and gave this dose to 38 Near Threatened G. himalayensis by oral gavage, with 15 control birds dosed with benzyl alcohol (the carrier solution for tolfenamic acid). Two birds given tolfenamic acid died with elevated uric acid levels and severe visceral gout, while the remainder showed no adverse clinical or biochemical signs. Secondly, four G. himalayensis were fed tissues from water buffaloes which had been treated with double the recommended veterinary dose of tolfenamic acid prior to death and compared to two birds fed uncontaminated tissue; none suffered any clinical effects. Finally, two captive Critically Endangered vultures, one G. bengalensis and one G. Indicus, were given the MLE dose by gavage and compared to two control birds; again, none suffered any clinical effects. The death of two G. himalayensis may have been an anomaly due to i) the high dose level used and ii) the high ambient temperatures at the time of the experiment. Tolfenamic acid is likely to be safe to Gyps vultures at concentrations encountered by wild birds and could therefore be promoted as a safe alternative to toxic NSAIDs. It is manufactured in the region, and is increasingly being used to treat livestock.

Protective role of Chlorella vulgaris with Thiamine against Paracetamol induced toxic effects on haematological, biochemical, oxidative stress parameters and histopathological changes in Wistar rats

Paracetamol is extensively consumed as an analgesic and antipyretic drug, but at a high dose level, it leads to deleterious side effects, such as hepatic and nephrotoxicity. This research aimed to estimate the prophylactic efficacy of Chlorella vulgaris and/or thiamine against paracetamol (P) induced hepatorenal and cardiac toxicity. Forty-eight female Wistar rats were randomly divided into eight equal groups (n = 6 rats). Group 1, normal control group. Group 2, Paracetamol group. Groups 3, 4 and 5 were treated with Silymarin drug, Chlorella vulgaris alga, Chlorella vulgaris alga supplemented with thiamine, respectively daily for 7 successive days, then all were administered Paracetamol (2gm/kg. bwt.). While, Groups 6, 7 and 8 were treated by Silymarin, Chlorella vulgaris alga, Chlorella vulgaris supplemented with thiamine, respectively daily for 7 successive days without paracetamol administration. Our results clarified that Paracetamol toxicity caused significant adverse effects on hematological, serum biochemical parameters, and oxidant -antioxidant status as well as histopathological picture of heart, liver, and kidney. However, in the Paracetamol intoxicated groups pretreatment either with Chlorella vulgaris alone or plus thiamine successfully improved the undesirable deleterious effects of paracetamol, and restored almost all variables to near their control levels. This study has finished to that oxidative stress participates in the pathogenesis of paracetamol-induced toxicity in rats and using Chlorella vulgaris alga either alone or plus thiamine alongside their health benefits can protect against oxidative harmful effects induced by paracetamol through their free radical scavenging and powerful antioxidant effects, and they can be used as propylactic agents against paracetamol-induced toxicity.

Safety assessment of essential oils from Xylopia aethiopica (Dunal) fruit from Nigeria

Introduction: The essential oils of Xylopia aethiopica fruits have been reported to possess numerous biochemical effects. However, no toxicological data is available regarding the safety evaluation of the essential oils from the plant spice. The present study was performed to evaluate the safety of essential oils from X. aethiopica (XAEO) fruit by acute and sub-acute oral toxicity studies in experimental rodents. Methods: In assessing the safety of XAEO, acute and sub-acute oral toxicity tests were performed following OECD guidelines 425 and 407, respectively, with slight modifications. At the end of each test, hematological and biochemical analysis of the collected blood was performed. Histopathological examination of vital organs of the animals was conducted for gross findings and for comparison to controls. Results: In acute oral toxicity, signs of toxicity were observed in the initial period of the experiment which culminated in the death of the mice before the end of the experiment. The sub-acute test observations indicated that generally, there were no significant differences (p<0.05) up to the high dose level compared to the controls. Conclusion: This study demonstrated the tolerability of XAEO administered daily for 28 days up to 450 mg/kg dose.

Experimental autoimmune encephalomyelitis inhibited by Huangqi Guizhi Wuwu Decoction by enhancing Th2 cytokine

Background: Current modern conventional medicine (MCM) on multiple sclerosis (MS) are non-specific immunosuppressive drugs, which remains many side effects. Huangqi Guizhi Wuwu decoction (HQGZWW) is a common formula of Chinese herbal medicine (CHM) has good effects on treatment of MS and its animal model, experimental autoimmune encephalomyelitis (EAE) very well, so it is very important to understand the precise mechanism. Our previous study suggested that CD8+ autoreactive T cells in EAE had a lower encephalitogenic function but were unique and independent on pathogenic of EAE rather than their CD4+ counterparts. The aims of current study were to determine the pathological interrelationship between CD4+ and CD8+ autoreactive T cells in MS/EAE upon the HQGZWW treatment.Methods: Female C57BL/6 mice (n=8, each group) were induced by myelin oligodendrocyte glycoprotein (MOG)35-55 peptide, and meantimely were treated with distilled water, prednisone, high dose or low dose HQGZWW. At 14 days after immunization, T cells were isolated from the spleen and purified as CD4+ and CD8+ T cells by using CD4 and CD8 isolation kits, and then the purity was determined by flow cytometric analysis. These cells were stimulated by MOG35-55 peptide and applied to proliferation assays. The interferon-gamma (IFN-g), interleukin (IL)-4 and IL-10 secretion of supernatant of cultured CD4+ and CD8+ T cells were measured by enzyme-linked immunosorbent assays (ELISA). For adoptive transfer, recipient mice were injected with MOG35-55 -specific CD8+ or CD4+ T cells. EAE clinical course was measured by EAE score at 0-5 scale and spinal cord was examined by staining with hematoxylin and eosin and Luxol fast blue staining.Results: For aEAE, there were significant improvement of EAE score in both HQGZWW high dose and prednisone groups by EAE score and pathological examination of spinal cord. CD8+ CD3+ and CD4+CD3+ cells were around 90% pure of total CD3+ cells after CD8/CD4 bead enrichment in 4 groups, respectively. These cells were stimulated by MOG35–55 peptide and applied to proliferation assays. There is lower antigen-specific responses of CD8+ as well as CD4+ T cells in HQGZWW high dose and prednisone group, compared with HQGZWW low dose and distilled water groups. For cytokine profiles, the CD4+ and CD8+ T cell supernatants contained lower levels of IFN-g and higher levels of IL-4 and IL-10 in HQGZWW high dose and prednisone groups compared with HQGZWW low dose and distilled water groups. Finally, HQGZWW had similar effect at high dose level to typical conventional medicine prednisone on tEAE, but no effect at low dose level.Conclusion: Our data suggested that HQGZWW had similar effect at high dose level to typical conventional medicine prednisone on EAE, but no effect at low dose level, and it suggested that the protection role of HQGZWW on EAE might be upon Th2 cytokine secretion profile by either MOG35–55 specific CD8+ or CD4+ T cells.

High-dose exposure to synthetic chemicals, hormones, or homeostatic substances in experimental animals or humans can induce artefactual pathology

The maximum tolerated dose (MTD) provides the highest probability of a positive result in a toxicology bioassay. The assumption underlying the MTD in animal bioassays is that adverse effects at very high doses are qualitatively the same as those occurring at low doses. In contrast with the MTD, the optimal top dose in a toxicology animal study is the highest dose that does not produce a pathological end point that presents no risk at lower doses, for example, the dose below which cytotoxicity induces tumors in the absence of genotoxicity or other carcinogenic mechanisms. Normal concentrations or biological activity levels of many substances necessary for normal physiological function induce pathology when found at high levels. For example, the demonstration that ingestion of abnormally high levels of certain dietary fats can cause or exacerbate atherosclerosis in relevant animal models like rhesus macaques does not demonstrate that normal levels of these fats should be considered as toxic. Excessive estrogenic stimulation is associated with breast, ovarian, and endometrial cancers. This does not imply that normal age-appropriate levels of estrogen are toxic. Normal wound healing is associated with transforming growth factors beta 1 and 2. Excessive stimulation of fibroblasts by these growth factors results in hypertrophic scarring and keloid formation. An understanding of the mode of action of a test substance can facilitate the selection of dose levels much higher than those expected to be experienced by humans, but not beyond a dose level at which pathology is an experimental artefact of the high-dose level.

Phase I, open-label study of pasireotide in patients with BRAF-wild type and NRAS-wild type, unresectable and/or metastatic melanoma

IntroductionSomatostatin analogues exert antitumour activity via direct and indirect mechanisms. The present study was designed to assess the safety and efficacy of pasireotide in patients with BRAF-wild type (WT) and NRAS-WT metastatic melanoma.Patients and methodsPatients with unresectable and/or metastatic melanoma or Merkel cell carcinoma were eligible. Pasireotide was administered at different doses for ≤8 weeks in dose-escalation phase, followed by long-acting pasireotide 80 mg or lower dose in case of toxicity in follow-up phase up to six additional months. Primary endpoint was safety in the first 8 weeks of dose-escalation phase.ResultsThe study was terminated early due to slow recruitment. Of the 10 patients with metastatic melanoma enrolled, only four reached the high dose level: two patients reached 3600 µg in dose-escalation and follow-up phases and two patients reached 3600 µg in dose-escalation and long-acting pasireotide 80 mg in follow-up phases and were stable for >5 months. Most common adverse events (AEs) during dose-escalation phase in ≥2 patients (20%) were: diarrhoea (50%), nausea (50%), fatigue (20%), hyperglycaemia (20%), hypophosphatemia (20%), chills (20%) and tumour pain (20%). Grade 3 or 4 study drug-related AEs were diarrhoea and nausea, reported in one patient. Partial response was documented in one patient and stable disease in another.ConclusionsPasireotide was well tolerated, and safety results were similar to those previously reported in other indications. Further studies are needed to evaluate its antitumour activity alone and in combination with other drugs in melanoma.

Metabolism of Dietary Glutamate in Adults

Background: Glutamate is a non-essential amino acid at the crossroads of nitrogen and energy metabolism. Glutamate metabolism is characterized by reactions that may be anabolic or catabolic in nature depending on the tissue (i.e., glutamate dehydrogenase, transaminases), and it can also be either the precursor or the metabolite of glutamine. Unlike glutamine, which is the form of interorgan ammonia transport, glutamate metabolism is mostly compartmentalized within the cells, its interorgan exchanges being limited to a flux from liver to muscle. Summary: Glutamate catabolism is extremely intense in the splanchnic area, such that after a meal (rich in proteins) almost no glutamate appears in the systemic circulation. However, this process is saturable as after glutamate loading at a high dose level, glutamate appears dose-dependently in the circulation. This systemic glutamate ­appearance is blunted if glutamate is co-ingested with a carbohydrate source. Key Messages: The underlying reason for this highly specific metabolism is that glutamate plays a key role in nitrogen homeostasis, and the organism does all it can to limit the bioavailability of glutamate, which can be neurotoxic in excess. As glutamate is never eaten alone, its bioavailability will be limited if not negligible, and no adverse effects are to be expected in adult humans.

2,4-Dinitroanisole (DNAN) (2014)

2,4-dinitroanisole (DNAN) is a warhead explosive currently under investigation as a replacement for TNT in melt-cast insensitive munitions. In animal studies, DNAN is a mild ocular and skin irritant with a significant potential for dermal absorption. It is not a dermal sensitizer. Acute and subacute rat inhalation studies demonstrated minimal toxicity with LC50 and LOAEL endpoints of 2.9 and 150 mg/m3, respectively. In rat oral toxicity studies (14 and 90 days) organ weight and clinical chemistry changes suggested hepatocellular injury and anemia, particularly in females. In males there was evidence of testicular injury at the high-dose level (80 mg/kg/day). The NOAELs for the 14- and 90-day studies were 25 and 5 mg/kg/day, respectively, with a calculated BMDL10 value of 0.93 mg/kg/day. No chronic, carcinogenicity or reproductive/developmental toxicity data were available for DNAN, but a maternal and fetal NOAEL of 5.1 mg/kg/day was inferred. DNAN is considered non-mutagenic and non-genotoxic. It is metabolized in vivo to 2,4-dinitrophenol (DNP), but other details of its metabolism or pharmacokinetics are unknown. There are considerable toxicity data for DNP, a known un-coupler of oxidative phosphorylation among other things, and these data may further inform regarding the safety of DNAN. In humans, DNAN was a component of louse powder (prior to DDT) with no reported safety concerns. However, its handling and use as a munition component presents a potential occupational hazard by both inhalation and dermal routes of exposure. Considering both DNAN and DNP toxicity endpoints, the recommended Workplace Environmental Exposure limit for DNAN is 0.1 mg/m2 (8-h time weighted average).

Toxicity Evaluation of Pũrṇa Cantirotaya Centũram, a Siddha Medicine in Wistar Rats

Pũrṇa Cantirotaya Centũram (PCC), a herbometallic formulation of Siddha medicine, consists of mercury, sulphur, and gold, processed with red cotton flower and plantain stem pith juices. To evaluate its safety, acute and 28-day repeated oral toxicity studies were performed following OECD test guidelines 423 and 407, respectively. In acute study, PCC was administered orally at 5, 50, 300, and 2000 mg/kg body weight. Animals were observed for toxic signs for 14 days. Gross pathology was performed at the end of the study. In repeated dose toxicity study, PCC was administered at 2.5, 25, and 50 mg/kg body weight daily for 28 days. Satellite groups (control and high dose) were also maintained to determine the delayed onset toxicity of PCC. In acute toxicity study, no treatment related death or toxic signs were observed. It revealed that the LD50 cut-off value of PCC is between 2000 and 5000 mg/kg body weight. The repeated dose study did not show evidence of any treatment related changes in all observations up to the high dose level, when compared with the control. Histopathological examination revealed no abnormalities except mild hyperplasia of stomach in high dose group. This study provides scientific validation for the safety of PCC.