Un-In Wu

Melatonin preserves longevity protein (sirtuin 1) expression in the hippocampus of total sleep-deprived rats.

Abstract:  Sleep disorders cause cognitive dysfunction in which impaired neuronal plasticity in the hippocampus may underline the molecular mechanisms of this deficiency. As sirtuin 1 (SIRT1) plays an important role in maintaining metabolic homeostasis and neuronal plasticity, this study is aimed to determine whether melatonin exerts beneficial effects on preserving SIRT1 activation following total sleep deprivation (TSD). TSD was performed by disc on water method for five consecutive days. During this period, animals daily received melatonin at doses of 5, 25, 50 or 100 mg/kg. The cytochrome oxidase (COX) histochemistry, SIRT1 immunohistochemistry together with Morris water maze learning test were performed to examine the metabolic, neurochemical, as well as the behavioral changes in neuronal plasticity, respectively. The results indicate that in normal rats, numerous COX and SIRT1 positive‐labeled neurons with strong staining intensities were found in hippocampal pyramidal and granular cell layers. Following TSD, both COX and SIRT1 reactivities were drastically decreased as revealed by reduced staining pattern and labeling frequency. Behavioral data corresponded well with morphological findings in which spatial memory test in water maze was significantly impaired after TSD. However, in rats receiving different doses of melatonin, both COX and SIRT1 expressions were successfully preserved. Considerably better performance on behavioral testing further strengthened the beneficial effects of melatonin. These findings suggest that melatonin may serve as a novel therapeutic strategy directed for preventing the memory deficits resulting from TSD, possibly by effectively preserving the metabolic function and neuronal plasticity engaged in maintaining cognitive activity.

Host susceptibility to non-tuberculous mycobacterial infections

Non-tuberculous mycobacteria cause a broad range of clinical disorders, from cutaneous infections, such as cervical or intrathoracic lymphadenitis in children, to disseminated infections at all ages. Recognition of the underlying immune defect is crucial for rational treatment, preventive care, family screening, and, in some cases, transplantation. So far, at least seven autosomal mutations (in IL12B, IL12RB1, ISG15, IFNGR1, IFNGR2, STAT1, and IRF8) and two X-linked mutations (in IKBKG and CYBB), mostly presenting in childhood, have been reported to confer susceptibility to disseminated non-tuberculous mycobacterial infection. GATA2 deficiency and anti-interferon γ autoantibodies also give rise to disseminated infection, typically in late childhood or adulthood. Furthermore, isolated pulmonary non-tuberculous mycobacterial infection has been increasing in prevalence in people without recognised immune dysfunction. In this Review, we discuss how to detect and differentiate host susceptibility factors underlying localised and systemic non-tuberculous mycobacterial infections.

Incidence and species distribution of candidaemia in Asia: a laboratory-based surveillance study

The epidemiology of candidaemia varies between hospitals and geographic regions. Although there are many studies from Asia, a large-scale cross-sectional study across Asia has not been performed. We conducted a 12-month, laboratory-based surveillance of candidaemia at 25 hospitals from China, Hong Kong, India, Singapore, Taiwan and Thailand. The incidence and species distribution of candidaemia were determined. There were 1601 episodes of candidaemia among 1.2 million discharges. The overall incidence was 1.22 episodes per 1000 discharges and varied among the hospitals (range 0.16-4.53 per 1000 discharges) and countries (range 0.25-2.93 per 1000 discharges). The number of Candida blood isolates and the total number of fungal isolates were highly correlated among the six countries (R² = 0.87) and 25 hospitals (R² = 0.77). There was a moderate correlation between incidence of candidaemia and the intensive care unit (ICU)/total bed ratio (R² = 0.47), although ICUs contributed to only 23% of candidaemia cases. Of 1910 blood isolates evaluated, Candida albicans was most frequently isolated (41.3%), followed by Candida tropicalis (25.4%), Candida glabrata (13.9%) and Candida parapsilosis (12.1%). The proportion of C. tropicalis among blood isolates was higher in haemato-oncology wards than others wards (33.7% versus 24.5%, p 0.0058) and was more likely to be isolated from tropical countries than other Asian countries (46.2% versus 18.9%, p 0.04). In conclusion, the ICU settings contribute, at least in part, to the incidence variation among hospitals. The species distribution is different from Western countries. Both geographic and healthcare factors contribute to the variation of species distribution.

Prognostic factors for fatal adult influenza pneumonia

OBJECTIVES To elucidate the prognostic factors for fatal adult influenza pneumonia. METHODS Complicated influenza pneumonia is a notifiable disease in Taiwan. In this retrospective nationwide cohort, medical records were reviewed in 38 qualifying cases from 2001 to 2007. In-hospital mortality was the primary endpoint of this study. RESULTS The median patient age was 52 years, with the in-hospital mortality rate of 44.7%. Influenza A virus was found in 25 patients and influenza B was in 13 patients. Fifty percent of patients had no comorbidities. More than half of the patients developed sepsis, septic shock, respiratory failure or acute respiratory distress syndrome. The median duration from symptom onset to hospital visit was 3 days, and from hospital visit to death was 4 days. A univariate analysis demonstrated poor prognosis in patients with shock, respiratory rate > or =25/min, arterial pH<7.35, creatinine> or =2mg/dL and Pneumonia Severity Index IV or V. A multivariate analysis showed an association with mortality in patients with APACHE II score > or =20 (hazard ratio 5.941, p=0.024) or PaO(2)/FiO(2) ratio <150 (hazard ratio 4.194, p=0.017). CONCLUSIONS Clinical knowledge of identified prognostic factors for mortality may aid management of adult influenza pneumonia.

Carbapenem-Nonsusceptible Enterobacteriaceae in Taiwan

A total of 1135 carbapenem-resistant (nonsusceptible) Enterobacteriaceae (CRE) isolates were recovered between November 2010 and July 2012 (517 from 2010-2011 and 618 from 2012) from 4 hospitals in Taiwan. Carbapenemase-producing Enterobacteriaceae (CPE) comprised 5.0% (57 isolates), including 17 KPC-2 (16 Klebsiella pneumoniae and 1 Escherichia coli), 1 NDM-1 (K. oxytoca), 37 IMP-8 (26 Enterobacter cloacae, 4 Citrobacter freundii, 4 Raoultella planticola, 1 K. pneumoniae, 1 E. coli and 1 K. oxytoca), and 2 VIM-1 (1 E. cloacae, 1 E. coli). The KPC-2-positive K. pneumoniae were highly clonal even in isolates from different hospitals, and all were ST11. IMP-8 positive E. cloacae from the same hospitals showed higher similarity in PFGE pattern than those from different hospitals. A total of 518 CRE isolates (45.6%) were positive for bla ESBL, while 704 (62.0%) isolates were bla AmpC-positive, 382 (33.6% overall) of which carried both bla ESBL and bla AmpC. CTX-M (414, 80.0%) was the most common bla ESBL, while DHA (497, 70.6%) and CMY (157, 22.3%) were the most common bla AmpC. Co-carriage of bla ESBL and bla AmpC was detected in 31 (54.4%) and 15 (26.3%) of the 57 CPE, respectively. KPC-2 was the most common carbapenemase detected in K. pneumoniae (2.8%), while IMP-8 was the most common in E. cloacae (9.7%). All KPC-2-positive CRE were resistant to all three tested carbapenems. However, fourteen of the 37 IMP-8-positive CRE were susceptible to both imipenem and meropenem in vitro. Intra- and inter-hospital spread of KPC-2-producing K. pneumoniae and IMP-8-producing E. cloacae likely occurred. Although the prevalence of CPE is still low, careful monitoring is urgently needed. Non-susceptibility to ertapenem might need to be considered as one criterion of definition for CRE in areas where IMP type carbapenemase is prevalent.

Melatonin inhibits microglial activation, reduces pro-inflammatory cytokine levels, and rescues hippocampal neurons of adult rats with acute Klebsiella pneumoniae meningitis.

Abstract:  Acute bacterial meningitis caused by Klebsiella pneumoniae (K. pneumoniae) is a major health threat with a high mortality rate and severe neuro‐cognitive sequelae. The intense pro‐inflammatory cytokine released from calcium‐mediated microglial activation plays an important role in eliciting neuronal damage in the hippocampal region. Considering melatonin possesses anti‐inflammatory and immuno‐modulatory properties, the present study determined whether melatonin can effectively decrease inflammatory responses and prevent hippocampal damage in animals subjected to K. pneumoniae. Adult rats inoculated with K. pneumoniae received a melatonin injection immediately thereafter at doses of 5, 25, 50, or 100 mg/kg. Following 24 h of survival, all experimental animals were processed for time‐of‐flight secondary ion mass spectrometry (for detecting glial calcium intensity), isolectin‐B4 histochemistry (reliable marker for microglial activation), pro‐inflammatory cytokine measurement as well as cytochrome oxidase and in situ dUTP end‐labeling (representing neuronal bio‐energetic status and apoptotic changes, respectively). Results indicate that in K. pneumoniae‐infected rats, numerous calcium‐enriched microglia, enhanced pro‐inflammatory cytokine, and various apoptotic neurons with low bio‐energetic activity were detected in hippocampus. Following melatonin administration, however, all parameters including glial calcium intensity, microglial activation, pro‐inflammatory cytokine levels, and number of apoptotic neurons were successfully decreased with maximal change observed at a melatonin dose of 100 mg/kg. Enzymatic data corresponded well with above findings in which all surviving neurons displayed high bio‐energetic activity. As effectively reducing glia‐mediated inflammatory response is neuro‐protective to hippocampal neurons, the present study supports the clinical use of melatonin as a potential therapeutic agent to counteract K. pneumoniae meningitis‐induced neuro‐cognitive damage.

Melatonin preserves superoxide dismutase activity in hypoglossal motoneurons of adult rats following peripheral nerve injury.

Abstract:  Peripheral nerve injury (PNI) produces functional changes in lesioned neurons in which oxidative stress is considered to be the main cause of neuronal damage. As superoxide dismutase (SOD) is an important antioxidative enzyme involved in redox regulation of oxidative stress, the present study determined whether melatonin would exert its beneficial effects by preserving the SOD reactivity following PNI. Adult rats subjected to hypoglossal nerve transection were intraperitoneally injected with melatonin at ones for 3, 7, 14, 30 and 60 days successively. The potential neuroprotective effects of melatonin were quantitatively demonstrated by neuronal nitric oxide synthase (nNOS), mitochondrial manganese SOD (Mn‐SOD), and cytosolic copper‐zinc SOD (Cu/Zn‐SOD) immunohistochemistry. The functional recovery of the lesioned neurons was evaluated by choline acetyltransferase (ChAT) immunohistochemistry along with the electromyographic (EMG) recordings of denervation‐induced fibrillation activity. The results indicate that following PNI, the nNOS immunoreactivity was significantly increased in lesioned neurons peaking at 14 days. The up‐regulation of nNOS temporally coincided with the reduction of ChAT and SOD in which the Cu/Zn‐SOD showed a greater diminution than Mn‐SOD. However, following melatonin administration, the nNOS augmentation was successfully suppressed and the activities of Mn‐SOD, Cu/Zn‐SOD, and ChAT were effectively preserved at all postaxotomy periods. EMG data also showed a decreased fibrillation in melatonin‐treated groups, suggesting a potential effect of melatonin in promoting functional recovery. In association with its significant capacity in preserving SOD reactivity, melatonin is suggested to serve as a powerful therapeutic agent for treating PNI‐relevant oxidative damage.

Sleep deprivation predisposes liver to oxidative stress and phospholipid damage: a quantitative molecular imaging study

Sleep disorders are associated with an increased rate of various metabolic disturbances, which may be related to oxidative stress and consequent lipid peroxidation. Since hepatic phosphatidylcholine plays an important role in metabolic regulation, the aim of the present study was to determine phosphatidylcholine expression in the liver following total sleep deprivation. To determine the effects of total sleep deprivation, we used adult rats implanted for polygraphic recording. Phosphatidylcholine expression was examined molecularly by the use of time‐of‐flight secondary ion mass spectrometry, along with biochemical solid‐phase extraction. The parameters of oxidative stress were investigated by evaluating the hepatic malondialdehyde levels as well as heat shock protein 25 immunoblotting and immunohistochemistry. In normal rats, the time‐of‐flight secondary ion mass spectrometry spectra revealed specific peaks (m/z 184 and 224) that could be identified as molecular ions for phosphatidylcholine. However, following total sleep deprivation, the signals for phosphatidylcholine were significantly reduced to nearly one‐third of the normal values. The results of solid‐phase extraction also revealed that the phosphatidylcholine concentration was noticeably decreased, from 15.7 µmol g–1 to 9.4 µmol g–1, after total sleep deprivation. By contrast, the biomarkers for oxidative stress were drastically up‐regulated in the total sleep deprivation‐treated rats as compared with the normal ones (4.03 vs. 1.58 nmol mg–1 for malondialdehyde levels, and 17.1 vs. 6.7 as well as 1.8 vs. 0.7 for heat shock protein 25 immunoblotting and immunoreactivity, respectively). Given that phosphatidylcholine is the most prominent component of all plasma lipoproteins, decreased expression of hepatic phosphatidylcholine following total sleep deprivation may be attributed to the enhanced oxidative stress and the subsequent lipid peroxidation, which would play an important role in the formation or progression of total sleep deprivation‐induced metabolic diseases.

Rapid and sensitive determination of posaconazole in patient plasma by capillary electrophoresis with field-amplified sample stacking

The high morbidity and mortality associated with invasive fungal infections have increased the importance of improving treatment efficacy. Posaconazole is a novel agent with strong antifungal activity and low toxicity. The success of posaconazole pharmacotherapy strongly depends on precise controlling of concentration of the drug in the blood. In the present study, a solid phase extraction-capillary electrophoresis (SPE-CE) method was developed for rapid and accurate determination of posaconazole in the plasma of patients. We used the field-amplified sample stacking (FASS) technique to improve the sensitivity of CE, and applied the SPE procedures to reduce the matrix effect that was frequently encountered by biological samples in FASS system. Effect of filter types on the recovery rate of compounds with high lipophilicity was carefully investigated. Parameters affecting FASS performance were all optimized to obtain the best sensitivity with the highest speed. When using 1.25 M formic acid as the background electrolyte and 0.2 M formic acid in 95% (v/v) methanol as the sample solution, the limit of detection (LOD) for posaconazole was 10 ngmL(-1), with an analytical run time of less than 5 min. The relative standard deviation (RSD) of the peak area ratios for repeatability (intra-day, n=6) and intermediate precision (inter-day, n=3) were lower than 7.2% and 7.5%, respectively. The accuracy was tested by recovery, and the recovery rates were within 95.1% and 106.4%, respectively. The successful application of the developed method demonstrated its feasibility as an effective method for clinical use.

Risk Factors for Bloodstream Infections due to Extended-spectrum β-lactamase-producing Escherichia coli

BACKGROUND/PURPOSE The risk factors for production of extended-spectrum beta-lactamases (ESBLs) have rarely been studied for bloodstream infections of Escherichia coli alone. A case-control study was undertaken to identify the risk factors associated with bloodstream infections caused by ESBL producing E. coli. METHODS From January 1, 2005 to June 30, 2007, all patients with a confirmed diagnosis of bloodstream infection caused by ESBL-producing E. coli were reviewed. Each patient was matched with one control subject who experienced ESBL-negative E. coli bacteremia during the same study period. RESULTS Of the 97 patients diagnosed with ESBL-producing E. coli bacteremia, six were excluded owing to incomplete follow-up and missing data. Comparisons were made between 91 patients and their controls. Multivariate analysis identified urinary catheterization [odds ratio (OR) = 6.21, 95% confidence interval (CI) = 1.91-20.25; p = 0.003], prior exposure to antibiotics (OR = 2.93, 95% CI = 1.18-7.30; p = 0.021) and previous treatment with oxyimino-cephalosporins (OR = 5.16, 95% CI = 1.03-25.79; p = 0.046) as independent predictors for bloodstream infection by ESBL-producing E. coli. Conversely, patients classified as having a community-acquired infection were less likely to acquire bacteremia caused by ESBL-producing E. coli than those caused by non-ESBL-producing E. coli (OR = 0.22, 95% CI = 0.09-0.57; p = 0.002). CONCLUSION More judicious use of antimicrobial agents, especially oxyimino-cephalosporins, and avoidance of urinary catheterization may decrease the possibility of ESBL-producing E. coli bacteremia in hospitalized patients.