N-acetylcysteine for antioxidant therapy : pharmacology and clinical utility

Glutathione is an endogenous antioxidant and has a ubiquitous role in many of the body’s defences. Treatment with N -acetylcysteine (NAC) has been shown to increase levels of glutathione. NAC has been proposed as a treatment for several illnesses. Objectives : The efficacy and tolerability of NAC was examined across a range of conditions to evaluate the evidence supporting the use of NAC for each indication. Methods : A literature search was conducted using PubMed. Information was also collected from other online sources including the websites of the Therapeutic Goods Administration of Australia and the FDA. Results : Reports ranged from case studies to clinical trials. There is strong evidence to support the use of NAC for the treatment of paracetamol overdose and emerging evidence suggesting it has utility in psychiatric disorders, particularly schizophrenia and bipolar disorder. NAC is safe and well tolerated when administered orally but has documented risks with intravenous administration.

Chemical immobilization of adult female Weddell seals with tiletamine and zolazepam: effects of age, condition and stage of lactation

Background

Chemical immobilization of Weddell seals (Leptonychotes weddellii) has previously been, for the most part, problematic and this has been mainly attributed to the type of immobilizing agent used. In addition to individual sensitivity, physiological status may play an important role. We investigated the use of the intravenous administration of a 1:1 mixture of tiletamine and zolazepam (Telazol®) to immobilize adult females at different points during a physiologically demanding 5–6 week lactation period. We also compared performance between IV and IM injection of the same mixture.
Results

The tiletamine:zolazepam mixture administered intravenously was an effective method for immobilization with no fatalities or pronounced apnoeas in 106 procedures; however, there was a 25 % (one animal in four) mortality rate with intramuscular administration. Induction time was slightly longer for females at the end of lactation (54.9 ± 2.3 seconds) than at post-parturition (48.2 ± 2.9 seconds). In addition, the number of previous captures had a positive effect on induction time. There was no evidence for effects due to age, condition (total body lipid), stage of lactation or number of captures on recovery time.
Conclusion

We suggest that intravenous administration of tiletamine and zolazepam is an effective and safe immobilizing agent for female Weddell seals. Although individual traits could not explain variation in recovery time, we suggest careful monitoring of recovery times during longitudinal studies (> 2 captures). We show that physiological pressures do not substantially affect response to chemical immobilization with this mixture; however, consideration must be taken for differences that may exist for immobilization of adult males and juveniles. Nevertheless, we recommend a mass-specific dose of 0.50 – 0.65 mg/kg for future procedures with adult female Weddell seals and a starting dose of 0.50 mg/kg for other age classes and other phocid seals.

Fructose-1,6-Bisphosphatase overexpression in pancreatic [beta]-cells results in reduced insulin secretion : a new mechanism for fat-induced impairment of [beta]-cell function

Fructose-1,6-bisphosphatase (FBPase) is a gluconeogenic enzyme that is upregulated in islets or pancreatic beta-cell lines exposed to high fat. However, whether specific beta-cell upregulation of FBPase can impair insulin secretory function is not known. The objective of this study therefore is to determine whether a specific increase in islet beta-cell FBPase can result in reduced glucose-mediated insulin secretion.

To test this hypothesis, we have generated three transgenic mouse lines overexpressing the human FBPase (huFBPase) gene specifically in pancreatic islet beta-cells. In addition, to investigate the biochemical mechanism by which elevated FBPase affects insulin secretion, we made two pancreatic beta-cell lines (MIN6) stably overexpressing huFBPase.

FBPase transgenic mice showed reduced insulin secretion in response to an intravenous glucose bolus. Compared with the untransfected parental MIN6, FBPase-overexpressing cells showed a decreased cell proliferation rate and significantly depressed glucose-induced insulin secretion. These defects were associated with a decrease in the rate of glucose utilization, resulting in reduced cellular ATP levels.

Taken together, these results suggest that upregulation of FBPase in pancreatic islet beta-cells, as occurs in states of lipid oversupply and type 2 diabetes, contributes to insulin secretory dysfunction.

Increased nicotinamide nucleotide transhydrogenase levels predispose to insulin hypersecretion in a mouse strain susceptible to diabetes

Aims/hypothesis Insulin hypersecretion may be an independent predictor of progression to type 2 diabetes. Identifying genes affecting insulin hypersecretion are important in understanding disease progression. We have previously shown that diabetes-susceptible DBA/2 mice congenitally display high insulin secretion. We studied this model to map and identify the gene(s) responsible for this trait.

Methods Intravenous glucose tolerance tests followed by a genome-wide scan were performed on 171 (C57BL/6 × DBA/2) × C57BL/6 backcross mice.

Results A quantitative trait locus, designated hyperinsulin production-1 (Hip1), was mapped with a logarithm of odds score of 7.7 to a region on chromosome 13. Production of congenic mice confirmed that Hip1 influenced the insulin hypersecretion trait. By studying appropriate recombinant inbred mouse strains, the Hip1 locus was further localised to a 2 Mb interval, which contained only nine genes. Expression analysis showed that the only gene differentially expressed in islets isolated from the parental strains was Nnt, which encodes the mitochondrial proton pump, nicotinamide nucleotide transhydrogenase (NNT). We also found in five mouse strains a positive correlation (r 2  = 0.90, p < 0.01) between NNT activity and first-phase insulin secretion, emphasising the importance of this enzyme in beta cell function. Furthermore, of these five strains, only those with high NNT activity are known to exhibit severe diabetes after becoming obese.

Conclusions/interpretation Insulin hypersecretion is associated with increased Nnt expression. We suggest that NNT must play an important role in beta cell function and that its effect on the high insulin secretory capacity of the DBA/2 mouse may predispose beta cells of these mice to failure.

Differential effect of inbred mouse strain (C57BL/6, DBA/2, 129T2) on insulin secretory function in response to a high fat diet

The increasing production of genetically-modified mouse models has necessitated studies to determine the inherent physiological characteristics of commonly used mouse strains. In this study we examined insulin secretory function in response to an intravenous bolus of glucose or glucose plus arginine in anesthetized C57BL/6, DBA/2 and 129T2 mice fed either a control or high fat diet for 6 weeks. The results show that 129T2 mice had higher fasting plasma glucose levels and lower fasting plasma insulin levels compared with C57BL/6 and DBA/2 mice regardless of diet. Furthermore, 129T2 mice were glucose intolerant and secreted significantly less insulin in response to glucose and glucose plus arginine irrespective of diet compared with the other two strains of mice. DBA/2 mice hypersecreted insulin in response to glucose and glucose plus arginine compared with C57BL/6 and 129T2 mice. Moreover while first phase insulin secretion was appropriately increased in response to the high fat diet in C57BL/6 and 129T2 mice, this was not the case for DBA/2 mice. Mean islet area was decreased in response to a high fat diet in DBA/2 mice, while there was no dietary effect on the other two strains. This study highlights the inherent genetic differences that exist among seemingly normal strains of mice that are commonly used to make transgenic and knockout mice. Understanding these differences will provide researchers with the information to choose the appropriate genetic background on which to express their particular genetic alteration.

Evidence that renal arginine transport is impaired in spontaneously hypertensive rats

Low renal nitric oxide (NO) bioavailability contributes to the development and maintenance of chronic hypertension. We investigated whether impaired L-arginine transport contributes to low renal NO bioavailability in hypertension. Responses of renal medullary perfusion and NO concentration to renal arterial infusions of the L-arginine transport inhibitor L-lysine (10 μmol·kg⁻¹·min⁻¹; 30 min) and subsequent superimposition of L-arginine (100 μmol·kg⁻¹·min⁻¹; 30 min), the NO synthase inhibitor N^G-nitro-L-arginine (2.4 mg/kg; iv bolus), and the NO donor sodium nitroprusside (0.24 μg·kg⁻¹·min⁻¹) were examined in Sprague-Dawley rats (SD) and spontaneously hypertensive rats (SHR). Renal medullary perfusion and NO concentration were measured by laser-Doppler flowmetry and polarographically, respectively, 5.5 mm below the kidney surface. Renal medullary NO concentration was less in SHR (53 ± 3 nM) compared with SD rats (108 ± 12 nM; P = 0.004). L-Lysine tended to reduce medullary perfusion (−15 ± 7%; P = 0.07) and reduced medullary NO concentration (−9 ± 3%; P = 0.03) while subsequent superimposition of L-arginine reversed these effects of L-lysine in SD rats. In SHR, L-lysine and subsequent superimposition of L-arginine did not significantly alter medullary perfusion or NO concentration. Collectively, these data suggest that renal L-arginine transport is impaired in SHR. Renal L-[³H]arginine transport was less in SHR compared with SD rats (P = 0.01). Accordingly, we conclude that impaired arginine transport contributes to low renal NO bioavailability observed in the SHR kidney.

Enhanced recovery after surgery program for elective adbominal surgery at three Victorian hospitals

The aim of this study was to evaluate the anaesthesia care of an enhanced recovery after surgery (ERAS) program for patients having abdominal surgical in Victorian hospitals. The man outcome measure was the number of ERAS items implemented following introduction of the ERAS program. Secondary endpoints included process of care measures, outcomes and hospital stay. We used a before-and-after design; the control group was a prospective cohort (n=154) representing pre-existing practice for elective abdominal surgical patients from July 2009. The introduction of a comprehensive ERAS program took place over two months and included the education of surgeons, anaesthetists, nurses and allied health professionals. A post-implementation cohort (n=169) was enrolled in early 2010. From a total of 14 ERAS-recommended items, there were significantly more implemented in the post-ERAS period, median 8 (interquartile range of 7 to 9) vs 9 (8 to 10), P <0.0001. There were, however, persistent low rates of intravenous fluid restriction (25%) and early removal of urinary catheter (31%) in the post-ERAS period. ERAS patients had less pain and faster recovery parameters, and this was associated with a reduced hospital stay, geometric mean (SD) 5.7 (2.5) vs 7.4 (2.1) days, P=0.006. We found that perioperative anaesthesia practices can be readily modified to incorporate an enhanced recovery program in Victorian hospitals.

Enhanced Recovery After Surgery program for elective abdominal surgery at three Victorian hospitals

The aim of this study was to evaluate the anaesthesia care of an enhanced recovery after surgery (ERAS) program for patients having abdominal surgical in Victorian hospitals. The main outcome measure was the number of ERAS items implemented following introduction of the ERAS program. Secondary endpoints included process of care measures, outcomes and hospital stay. We used a before-and-after design; the control group was a prospective cohort (n=154) representing pre-existing practice for elective abdominal surgical patients from July 2009. The introduction of a comprehensive ERAS program took place over two months and included the education of surgeons, anaesthetists, nurses and allied health professionals. A post-implementation cohort (n=169) was enrolled in early 2010. From a total of 14 ERAS-recommended items, there were significantly more implemented in the post-ERAS period, median 8 (interquartile range 7 to 9) vs 9 (8 to 10), P <0.0001. There were, however, persistent low rates of intravenous fluid restriction (25%) and early removal of urinary catheter (31%) in the post-ERAS period. ERAS patients had less pain and faster recovery parameters, and this was associated with a reduced hospital stay, geometric mean (SD) 5.7 (2.5) vs 7.4 (2.1) days, P=0.006. We found that perioperative anaesthesia practices can be readily modified to incorporate an enhanced recovery program in Victorian hospitals.

A case of Kingella kingae endocarditis complicated by native mitral valve rupture

We report a case of Kingella kingae endocarditis in a patient with a history of recent respiratory tract infection and dental extraction. This case is remarkable for embolic and vasculitic phenomena in association with a large valve vegetation and valve perforation. Kingella kingae is an organism known to cause endocarditis, however early major complications are uncommon. Our case of Kingella endocarditis behaved in a virulent fashion necessitating a combined approach of intravenous antibiotic therapy and a valve replacement. It highlights the importance of expedited investigation for endocarditis in patients with Kingella bacteraemia.

Outpatient versus inpatient IV antibiotic management for pediatric oncology patients with low risk febrile neutropenia: a randomised trial

Febrile neutropenia (FN) is a frequent, serious complication of intensive pediatric chemotherapy regimens. The aim of this trial was to compare quality of life (QOL) between inpatient and outpatient intravenous antibiotic management of children and adolescents with low risk febrile neutropenia (LRFN).

Idle central venous catheter-days pose infection risk for patients after discharge from intensive care

This prospective observational study measured idle central venous catheter (CVC)-days (no medical indication), and ward clinicians' adherence to evidence-based practices for preventing short-term central line-associated bloodstream infections (CLABSIs). In 340 patients discharged from ICU over a 1-year period, 208 of 794 CVC-days (26.2%) were idle. Interventions to prevent CLABSIs were poorly implemented. Ward clinicians need education regarding risk management strategies to prevent CLABSIs, and clear accountability processes for prompt catheter removal are recommended.

Pharmacological management of aggression and violence.

The pharmacological management of violence and aggression is a common and substantial clinical dilemma in the emergency psychiatric situation. A literature search was conducted through PubMed and using the Cochrane Library. This was followed by a manual search of selected literature. Randomised controlled trials were sought that specifically addressed the acute situation, rather than the ongoing management of chronic conditions. There was a paucity of well-controlled data and insufficient evidence to support the use of many agents in emergency situations. Many studies had considerable limitations making comparison difficult. Efficacy data for a range of treatment options exists, including the use of classical and atypical anti-psychotic agents, benzodiazepines and combination therapies. Clinical risk, tolerability and environmental factors need to form part of a careful and considered judgement in the choice of treatment. Safety, tolerability and the potential for a positive experience are major considerations, thus paving the way for long term compliance.

CD8+ T cells from a novel T cell receptor transgenic mouse induce liver-stage immunity that can be boosted by blood-stage infection in rodent malaria

To follow the fate of CD8+ T cells responsive to Plasmodium berghei ANKA (PbA) infection, we generated an MHC I-restricted TCR transgenic mouse line against this pathogen. T cells from this line, termed PbT-I T cells, were able to respond to blood-stage infection by PbA and two other rodent malaria species, P. yoelii XNL and P. chabaudi AS. These PbT-I T cells were also able to respond to sporozoites and to protect mice from liver-stage infection. Examination of the requirements for priming after intravenous administration of irradiated sporozoites, an effective vaccination approach, showed that the spleen rather than the liver was the main site of priming and that responses depended on CD8α+ dendritic cells. Importantly, sequential exposure to irradiated sporozoites followed two days later by blood-stage infection led to augmented PbT-I T cell expansion. These findings indicate that PbT-I T cells are a highly versatile tool for studying multiple stages and species of rodent malaria and suggest that cross-stage reactive CD8+ T cells may be utilized in liver-stage vaccine design to enable boosting by blood-stage infections.

Superior performance of aptamer in tumor penetration over antibody : implication of aptamer-based theranostics in solid tumors

Insufficient penetration of therapeutic agents into tumor tissues results in inadequate drug distribution and lower intracellular concentration of drugs, leading to the increase of drug resistance and resultant failure of cancer treatment. Targeted drug delivery to solid tumors followed by complete drug penetration and durable retention will significantly improve clinical outcomes of cancer therapy. Monoclonal antibodies have been commonly used in clinic for cancer treatment, but their limitation of penetrating into tumor tissues still remains because of their large size. Aptamers, as "chemical antibodies", are 15-20 times smaller than antibodies. To explore whether aptamers are superior to antibodies in terms of tumor penetration, we carried out the first comprehensive study to compare the performance of an EpCAM aptamer with an EpCAM antibody in theranostic applications. Penetration and retention were studied in in vitro three-dimensional tumorspheres, in vivo live animal imaging and mouse colorectal cancer xenograft model. We found that the EpCAM aptamer can not only effectively penetrate into the tumorsphere cores but can also be retained by tumor sphere cells for at least 24 h, while limited tumor penetration by EpCAM antibody was observed after 4 h incubation. As observed from in vivo live animal imaging, EpCAM aptamers displayed a maximum tumor uptake at around 10 min followed by a rapid clearance after 80 min, while the signal of peak uptake and disappearance of antibody appeared at 3 h and 6 h after intravenous injection, respectively. The signal of PEGylated EpCAM aptamers in xenograft tumors was sustained for 26 h, which was 4.3-fold longer than that of the EpCAM antibody. Consistently, there were 1.67-fold and 6.6-fold higher accumulation of PEGylated aptamer in xenograft tumors than that of antibody, at 3 h and 24 h after intravenous administration, respectively. In addition, the aptamer achieved at least a 4-time better tumor penetration in xenograft tumors than that of the antibody at a 200 μm distances from the blood vessels 3 h after intravenous injection. Taken together, these data indicate that aptmers are superior to antibodies in cancer theranostics due to their better tumor penetration, more homogeneous distribution and longer retention in tumor sites. Thus, aptamers are promising agents for targeted tumor therapeutics and molecular imaging.

Evolving epidemiology of injecting drug use-associated infective endocarditis: a regional centre experience

INTRODUCTION AND AIMS: Injecting drug use (IDU) is a major risk factor for infective endocarditis (IE). An understanding of the epidemiology of IE and IDU is vital for delivery of health care for this disease. Our aim was to examine the rates of IDU-associated IE (IDU-IE) in a single centre over the last 12 years. DESIGN AND METHODS: Retrospective analysis of two cohorts of consecutive patients (n = 226) admitted with IE from 2002 to 2013. Numbers of cases and rates of IE were compared between two cohorts (2002-2006 and 2009-2013). Rate ratios were calculated using Poisson distributions. Poisson regression was used to examine relationship over time. RESULTS: One hundred thirty cases of endocarditis were seen in the first observation period (6 IDU-IE) and 96 in the second observation period (15 IDU-IE). The estimated incidence rate of IE had fallen from 10.1 to 6.45 per 100, 000 person-years [rate ratio 0.64, 95% confidence interval (CI) 0.48, 0.85]. In contrast, the estimated incidence rate of IDU-E has risen from 0.48 to 0.79 per 100, 000 person-years (rate ratio 1.65, 95% CI 0.59, 4.57). Incidence rate regression suggests that the number of IDU-IE cases is expected to increase by a factor of 1.25 (95%CI 1.09-1.44) for each increase of 1 year. DISCUSSION AND CONCLUSIONS: Over the last decade, there has been a decrease in incidence rate and total number of cases of IE but a rise in rate and number of cases of IDU-IE. This may indicate increasing IDU or increased rates of endocarditis in intravenous drug users in this region. This finding may inform health-care planning in the area.