Cisplatin, a platinum-containing antineoplastic drug: perspectives on analytical chemistry and prevention of ototoxicity

The platinum-containing drug cisplatin plays a key role in the curative and palliative treatment of many solid malignancies. Unfortunately, the treatment can lead to sensorineural hearing loss, which limits the use of the drug. High single and cumulative dose levels are risk factors, but there is a large interindividual variability in the susceptibility to the ototoxic effects. The mechanisms behind the ototoxicity have not been fully elucidated, but one hallmark is oxidative stress. Moreover, the ototoxicity is dependent on the exposure of cisplatin and/or its biotransformation product MHC in the perilymphatic compartment of the cochlea. The aim of the research presented in this thesis was to contribute to the development of treatment strategies against cisplatin-induced ototoxicity. Sulfur-containing nucleophiles are attractive candidate compounds against cisplatininduced hearing loss since they are prone to chemically interact with cisplatin and MHC and could potentially reduce the exposure of these platinum species in the cochlea. A second possible mechanism may be relief of oxidative stress. The aim of the in vitro study described in Paper I was to investigate how quickly the concentrations of cisplatin and MHC can be reduced in the presence of five sulfur-containing nucleophiles. The results showed that thiosulfate was a promising candidate for future studies in vivo, since it reacted fast with cisplatin and, in particular, with MHC. This conclusion was further supported by the fact that thiosulfate is an endogenous ion, is well tolerated, and has been used clinically for decades against e.g. cyanide poisoning. Systemic administration of thiosulfate has earlier been investigated in several in vitro and in vivo studies against cisplatin-induced ototoxicity. However, it has been unknown whether thiosulfate at all reaches the cochlea. In the study described in Paper II, it was demonstrated that the distribution of thiosulfate to the perilymphatic compartment was quick and extensive after an i.v. bolus injection in guinea pigs. Unfortunately, this way of administration of thiosulfate in connection with systemic cisplatin delivery is risky, since it may lead to decreased antitumoral effects due to inactivation of cisplatin and MHC not only in the cochlea but also in tumor tissues. In the studies on which Paper III is based, it was found that the ototoxicity in cisplatin-treated guinea pigs was reduced by a local administration strategy employing a thiosulfate-containing hyaluronan gel administered into the middle ear cavity three hours prior to the systemic cisplatin injection. When quantifying cisplatin, unselective methods are almost always used, which may confound the results. In the final study, on which Paper IV is based, a sensitive, robust, and fast method using liquid chromatography and UV detection for the selective analysis of cisplatin in blood was developed. This method will be a valuable instrument in future studies exploring the role of pharmacokinetic parameters of cisplatin for the ototoxic effects

Cisplatin and Oxaliplatin Toxicity: Importance of Cochlear Kinetics as a Determinant for Ototoxicity

Background Cisplatin is a commonly used platinum anti-cancer drug. Regrettably cisplatin has dose-limiting ototoxic side effects, e.g. the drug can induce an irreversible hearing loss. The ototoxic mechanisms of cisplatin have not been elucidated in the human ear and no clinically useful oto-protectors are yet available. Cisplatin is a necessary part of many treatment regimes. Its beneficial therapeutic effects might be reduced if cisplatin was excluded from the treatment in order to protect the hearing function. In this work the ototoxic effects of cisplatin are studied with the aim to better understand the mechanisms behind the irreversible hearing loss induced by this drug. Oxaliplatin is a second generation platinum-derivative anti-cancer drug, free from ototoxic side effects in clinical practice. The effects of oxaliplatin on the inner ear have been studied in this work and the results are compared with cisplatin treatment. The two drugs differ regarding both anti-cancer effects and side effects, which could be attributed to differences in pharmacokinetic factors, cellular uptake and apoptotic mechanisms. The thioredoxin redox system with the enzyme thioredoxin reductase (TrxR) was studied in cochleae due to a suggested DNA-independent apoptotic mechanism of the hair cells. The cochlear pharmacokinetics of cisplatin was assessed and the transport protein organic cation transporter 2 (OCT2) was studied in relation to the ototoxic effect of cisplatin. Material and methods Cultured human colon carcinoma cells and cell cultures of rat organ of Corti were used for apoptosis studies in vitro following exposure to cisplatin and oxaliplatin. Cisplatin and oxaliplatin were administered i.v. to guinea pigs, followed by in vivo sampling of blood, cerebrospinal fluid (CSF) and scala tympani (ST) perilymph. Liquid chromatography with post-column derivatization was used to determine the concentration of parent drug in the samples. Electrophysiological hearing thresholds and the loss of hair cells were assessed to evaluate their ototoxic effects. Phenformin, a potential blocker of OCT2 was administered and the ototoxic side effect of cisplatin was evaluated. For immunohistochemical studies, cochlea from rat, guinea pig and pig were used, where TrxR and OCT2 were evaluated in the cochlea. TrxR-assays were used to measure the TrxR activity in cochlear tissue, both in vivo and in vitro. Results The results from the in vitro studies showed that addition of either cisplatin or oxaliplatin to the culture medium in organ of Corti cell cultures caused a similar amount of outer hair cell loss and inhibition of TrxR activity. Cisplatin exposure to cultured human colon carcinoma cells also reduced the activity of TrxR. The results from the in vivo studies showed that a considerable concentration of cisplatin was present in ST perilymph as compared with weak concentrations of oxaliplatin after high dose oxaliplatin i.v. Ten minutes after cisplatin administration, its concentration in ST perilymph was 4-fold higher in the basal turn of the cochlea as compared to the apex. Cisplatin could be analysed in ST perilymph for up to 120 min. Phenformin i.v. did not reduce the ototoxic side-effect of cisplatin. Positive immunoreactivity to TrxR was evident in both hair cells and spiral ganglion cells. Futhermore, OCT2 was expressed in the supporting cells of organ of Corti and in the spiral ganglion cells. Conclusion The transport of cisplatin to the vulnerable cells of hearing seems to be of major importance for the ototoxic effects. An early high concentration of cisplatin in the base of the cochlea and delayed elimination of cisplatin from ST perilymph may be related to the cisplatin-induced loss of outer hair cells in the basal turn of the cochlea. Cisplatin and oxaliplatin both cause similar ototoxic effects when the organ of Corti is directly exposed in vitro. The thioredoxin redox system with the TrxR enzyme may well play a critical role in cisplatininduced ototoxicity. The presence of OCT2 in the supporting cells indicates that this transport protein is primarily not involved in the uptake of cisplatin from the systemic circulation but rather from the deeper compartments of the cochlea. The knowledge elicited in this work will hopefully suggest objectives for further studies in order to develop oto-protective treatments to preserve the hearing of cisplatin treated patients

Intraoperative assessment of biliary anatomy for prevention of bile duct injury: a review of current and future patient safety interventions

Background Bile duct injury (BDI) is a dreaded complication of cholecystectomy, often caused by misinterpretation of biliary anatomy. To prevent BDI, techniques have been developed for intraoperative assessment of bile duct anatomy. This article reviews the evidence for the different techniques and discusses their strengths and weaknesses in terms of efficacy, ease, and cost-effectiveness. Method PubMed was searched from January 1980 through December 2009 for articles concerning bile duct visualization techniques for prevention of BDI during laparoscopic cholecystectomy. Results Nine techniques were identified. The critical-view-of-safety approach, indirectly establishing biliary anatomy, is accepted by most guidelines and commentaries as the surgical technique of choice to minimize BDI risk. Intraoperative cholangiography is associated with lower BDI risk (OR 0.67, CI 0.61-0.75). However, it incurs extra costs, prolongs the operative procedure, and may be experienced as cumbersome. An established reliable alternative is laparoscopic ultrasound, but its longer learning curve limits widespread implementation. Easier to perform are cholecystocholangiography and dye cholangiography, but these yield poor-quality images. Light cholangiography, requiring retrograde insertion of an optical fiber into the common bile duct, is too unwieldy for routine use. Experimental techniques are passive infrared cholangiography, hyperspectral cholangiography, and near-infrared fluorescence cholangiography. The latter two are performed noninvasively and provide real-time images. Quantitative data in patients are necessary to further evaluate these techniques. Conclusions The critical-view-of-safety approach should be used during laparoscopic cholecystectomy. Intraoperative cholangiography or laparoscopic ultrasound is recommended to be performed routinely. Hyperspectral cholangiography and near-infrared fluorescence cholangiography are promising novel techniques to prevent BDI and thus increase patient safety

Effects of early probiotic supplementation in a pediatric setting : Focus on body composition, metabolism and inflammation

We aimed to determine the short- and long-term effects on growth, body composition, metabolic and inflammatory markers following supplementation with the probiotic Lactobacillus paracasei ssp. paracasei F19 (LF19) during weaning. Methods: One-hundred and seventy-nine healthy, infants in Umeå city, Västerbotten County were randomised to daily intake of cereals with (n=89) or without (n=90) LF19 108 colony-forming units from 4 to 13 months of age. Weight, length, head circumference and body composition, assessed by skinfold thickness, were examined at 4, 5.5, 6.5, 9, 12 and 13 months of age. Venous blood was drawn at 5.5 and 13 months. In all, 171 infants completed the intervention and were invited to a follow-up at 8-9 years of age between 2009 and 2011, 120 children participated. Weight, height, sagittal abdominal diameter and body composition (using Dual Energy X-ray Absorptiometry-scan) were measured. Data on weight and height at 4 years were collected from medical records. The families filled out a 4-day food record and a food frequency questionnaire, physical activity was assessed using a pedometer for 7 days. At 5.5, 13 months and 8-9 years of age we analysed the serum blood lipid profile. At 8-9 years fasting glucose, insulin, aspartate and alanine transaminases were analysed in serum. Homeostatic Model Assessment index was calculated. At follow-up serum adiponectin, high-sensitivity C-reactive protein and plasma C-peptide, ghrelin, gastric inhibitory polypeptide, glucagon-like peptide 1, glucagon, insulin, leptin, plasminogen activator inhibitor-1, resistin and visfatin were analysed. For characterisation of the plasma metabolome, a subgroup (n=40) was analysed at 5.5 and 13 months of age by gas chromatography time-of-flight mass spectrometry (GC-TOF/MS) analysis and in all (n=112) children at the follow-up using untargeted GC-GC/MS. Results: There were no differences between the LF19 and placebo group regarding body weight, length/height at any assessment from 4 months to 8-9 years of age; nor were there any differences between the groups in body composition. In the LF19 group 19 % were overweight/obese, the corresponding number was 21 % in the placebo group (p=0.78). Analysed metabolic and inflammatory markers, both during the intervention and the follow-up did not differ between the two groups. At 13 months of age lower levels of palmitic acid and palmitoleic acid (both p<0.04) and higher levels of putrescine (p<0.01) were seen in the LF19 compared to the placebo group. These differences did not persist at 8-9 years of age. At that age, we found statistically stronger models when comparing overweight/obese and normal weight children as well as in relation to sex. Conclusion: Early intervention with the probiotic LF19 at the time of weaning exerted transient effects on the metabolome. In a long-term perspective, we found neither benefit nor harm on growth, body composition, metabolic or inflammatory markers following supplementation with LF19 during weaning

Anhörigas erfarenheter av palliativ vård : En litteraturöversikt

Bakgrund: Tidigare forskning visade att det finns hinder för en god palliativ vård. Sjuksköterskor erfor att bemötandet av anhöriga medför en problematik som påverkar den palliativa vårdens kvalitet. Detta påverkade patienter eftersom en viktig del av patienters liv är dess anhöriga. Syfte: Att beskriva anhörigas erfarenheter av palliativ vård. Metod: En allmän litteraturöversikt enligt Friberg med elva artiklar av både kvalitativ och kvantitativ ansats. Resultat: Det identifierades fem teman viktiga för anhöriga som hade närstående som vårdades palliativt. Dessa teman var vikten av kommunikation och information från vårdteam, delaktighet i vården och samarbete med vårdteamet utifrån önskemål, att erhålla stöd och förståelse, att erhålla värdighet och respekt samt förändringar i livet. Det visade att det fanns kommunikations- och informationsbrister. Anhöriga uppskattade att bli bemötta med värdighet, respekt och bli inkluderade i vården samt att erhålla stöd och förståelse var centralt för anhöriga. Slutsats: Kunskap och utbildning är viktigt för sjuksköterskor för att kunna bemöta anhöriga och lindra deras lidande. Anhöriga som bemöttes av sjuksköterskor som hade god kunskap inom den palliativa vården hade ett mindre lidande.