Michael A. Kuskowski

Brain amyloid-β oligomers in ageing and Alzheimer’s disease

Alzheimers disease begins about two decades before the onset of symptoms or neuron death, and is believed to be caused by pathogenic amyloid-β aggregates that initiate a cascade of molecular events culminating in widespread neurodegeneration. The microtubule binding protein tau may mediate the effects of amyloid-β in this cascade. Amyloid plaques comprised of insoluble, fibrillar amyloid-β aggregates are the most characteristic feature of Alzheimers disease. However, the correspondence between the distribution of plaques and the pattern of neurodegeneration is tenuous. This discrepancy has stimulated the investigation of other amyloid-β aggregates, including soluble amyloid-β oligomers. Different soluble amyloid-β oligomers have been studied in several mouse models, but not systematically in humans. Here, we measured three amyloid-β oligomers previously described in mouse models-amyloid-β trimers, Aβ*56 and amyloid-β dimers-in brain tissue from 75 cognitively intact individuals, ranging from young children to the elderly, and 58 impaired subjects with mild cognitive impairment or probable Alzheimers disease. As in mouse models, where amyloid-β trimers appear to be the fundamental amyloid-β assembly unit of Aβ*56 and are present in young mice prior to memory decline, amyloid-β trimers in humans were present in children and adolescents; their levels rose gradually with age and were significantly above baseline in subjects in their 70s. Aβ*56 levels were negligible in children and young adults, rose significantly above baseline in subjects in their 40s and increased steadily thereafter. Amyloid-β dimers were undetectable until subjects were in their 60s; their levels then increased sharply and correlated with plaque load. Remarkably, in cognitively intact individuals we found strong positive correlations between Aβ*56 and two pathological forms of soluble tau (tau-CP13 and tau-Alz50), and negative correlations between Aβ*56 and two postsynaptic proteins (drebrin and fyn kinase), but none between amyloid-β dimers or amyloid-β trimers and tau or synaptic proteins. Comparing impaired with age-matched unimpaired subjects, we found the highest levels of amyloid-β dimers, but the lowest levels of Aβ*56 and amyloid-β trimers, in subjects with probable Alzheimers disease. In conclusion, in cognitively normal adults Aβ*56 increased ahead of amyloid-β dimers or amyloid-β trimers, and pathological tau proteins and postsynaptic proteins correlated with Aβ*56, but not amyloid-β dimers or amyloid-β trimers. We propose that Aβ*56 may play a pathogenic role very early in the pathogenesis of Alzheimers disease.

Escherichia coli Sequence Type 131 (ST131) Subclone H30 as an Emergent Multidrug-Resistant Pathogen Among US Veterans

BACKGROUND Escherichia coli sequence type 131 (ST131), typically fluoroquinolone-resistant (FQ-R) and/or extended-spectrum β-lactamase (ESBL)-producing, has emerged globally. We assessed its prevalence and characteristics among US veterans. METHODS In 2011, 595 de-identified E. coli clinical isolates were collected systematically within 3 resistance groups (FQ-susceptible [FQ-S], FQ-R, and ESBL-producing) from 24 nationally distributed Veterans Affairs Medical Centers (VAMCs). ST131 and its H30 subclone were detected by polymerase chain reaction and compared with other E. coli for molecular traits, source, and resistance profiles. RESULTS ST131 accounted for 78% (184/236) of FQ-R and 64.2% (79/123) of ESBL-producing isolates, but only 7.2% (17/236) of FQ-S isolates (P < .001). The H30 subclone accounted for ≥95% of FQ-R and ESBL-producing, but only 12.5% of FQ-S, ST131 isolates (P < .001). By back-calculation, 28% of VAMC E. coli isolates nationally represented ST131. Overall, ST131 varied minimally in prevalence by specimen type, inpatient/outpatient source, or locale; was the most prevalent ST, followed distantly by ST95 and ST12 (13% each); and accounted for ≥40% (β-lactams), >50% (trimethoprim-sulfamethoxazole , multidrug), or >70% (ciprofloxacin, gentamicin) of total antimicrobial resistance. FQ-R and ESBL-producing ST131 isolates had higher virulence scores than corresponding non-ST131 isolates. ST131 pulsotypes overlapped extensively among VAMCs. CONCLUSIONS Among US veterans, ST131, primarily its H30 subclone, accounts for most antimicrobial-resistant E. coli and is the dominant E. coli strain overall. Possible contributors include multidrug resistance, extensive virulence gene content, and ongoing transmission. Focused attention to ST131, especially its H30 subclone, could reduce infection-related morbidity, mortality, and costs among veterans.

Baseline and serial measurements of galectin-3 in patients with heart failure: relationship to prognosis and effect of treatment with valsartan in the Val-HeFT.

This study was conducted to determine whether galectin‐3, a β‐galactoside‐binding lectin, plays a role in the pathogenesis of heart failure (HF).

Comparison of Escherichia coli ST131 pulsotypes, by epidemiologic traits, 1967-2009

Certain high-prevalence pulsed-field gel electrophoresis types exhibited distinctive temporal patterns and epidemiologic associations.

Molecular Epidemiology of Escherichia coli Sequence Type 131 and Its H30 and H30-Rx Subclones among Extended-Spectrum-β-Lactamase-Positive and -Negative E. coli Clinical Isolates from the Chicago Region, 2007 to 2010

ABSTRACT We assessed Escherichia coli ST131 and its H30 and H30-Rx subclones for virulence genes, antimicrobial resistance, and extended-spectrum beta-lactamase (ESBL) type. Although both subclones were associated with ESBL production, H30-Rx isolates had higher resistance scores and were associated specifically with CTX-M-15. Three virulence genes (iha, sat, and iutA) were more prevalent among H30 than non-H30 ST131 isolates. Thus, the H30 and H30-Rx subclones are more antimicrobial resistant and have virulence profiles that are distinct from those of non-H30 ST131 isolates.

Complications of Foley Catheters—Is Infection the Greatest Risk?

PURPOSE Foley catheters cause a variety of harms, including infection, pain and trauma. Although symptomatic urinary tract infection and asymptomatic bacteriuria are frequently discussed, genitourinary trauma receives comparatively little attention. MATERIALS AND METHODS A dedicated Foley catheter nurse prospectively reviewed the medical records of inpatients with a Foley catheter at the Minneapolis Veterans Affairs Medical Center from August 21, 2008 to December 31, 2009. Daily surveillance included Foley catheter related bacteriuria and trauma. Data were analyzed as the number of event days per 100 Foley catheter days. RESULTS During 6,513 surveyed Foley catheter days, urinalysis/urine culture was done on 407 (6.3%) days. This testing identified 116 possible urinary tract infection episodes (1.8% of Foley catheter days), of which only 21 (18%) involved clinical manifestations. However, the remaining 95 asymptomatic bacteriuria episodes accounted for 39 (70%) of 56 antimicrobial treated possible urinary tract infection episodes (for proportion of treated episodes with vs without symptomatic urinary tract infection manifestations, p = 0.005). Concurrently 100 instances of catheter associated genitourinary trauma (1.5% of Foley catheter days) were recorded, of which 32 (32%) led to interventions such as prolonged catheterization or cystoscopy. Trauma prompting an intervention accounted for as great a proportion of Foley catheter days (0.5%) as did symptomatic urinary tract infection (0.3%) (p = 0.17). CONCLUSIONS In this prospective surveillance project, intervention triggering Foley catheter related genitourinary trauma was as common as symptomatic urinary tract infection. Moreover, despite recent increased attention to the distinction between asymptomatic bacteriuria and symptomatic urinary tract infection in catheterized patients, asymptomatic bacteriuria accounted for significantly more antimicrobial treatment than did symptomatic urinary tract infection. Elimination of unnecessary Foley catheter use could prevent symptomatic urinary tract infection, unnecessary antimicrobial therapy for asymptomatic bacteriuria and Foley catheter related trauma.

Opioid requirement, opioid receptor expression, and clinical outcomes in patients with advanced prostate cancer.

Preclinical studies show that opioids stimulate angiogenesis and tumor progression through the mu opioid receptor (MOR). Although MOR is overexpressed in several human malignancies, the effect of chronic opioid requirement on cancer progression or survival has not been examined in humans.

Augmentation of response and remission to serial intravenous subanesthetic ketamine in treatment resistant depression

BACKGROUND Ketamine has been showing high efficacy and rapid antidepressant effect. However, studies of ketamine infusion wash subjects out from prior antidepressants, which may be impractical in routine practice. In this study, we determined antidepressant response and remission to six consecutive ketamine infusions while maintaining stable doses of antidepressant regimen. We also examined the trajectory of response and remission, and the time to relapse among responders. METHODS TRD subjects had at least 2-month period of stable dose of antidepressants. Subjects completed six IV infusions of 0.5mg/kg ketamine over 40min on a Monday-Wednesday-Friday schedule during a 12-day period participants meeting response criteria were monitored for relapse for 4 weeks. RESULTS Fourteen subjects were enrolled. Out of twelve subjects who completed all six infusions, eleven (91.6%) achieved response criterion while eight (66.6%) remitted. After the first infusion, only three and one out of twelve subjects responded and remitted, respectively. Four achieved response and six remitted after 3 or more infusions. Five out of eleven subjects remain in response status throughout the 4 weeks of follow-up. The mean time for six subjects who relapsed was 16 days. LIMITATIONS Small sample and lack of a placebo group limits the interpretation of efficacy. CONCLUSIONS Safety and efficacy of repeated ketamine infusions were attained without medication-free state in patients with TRD. Repeated infusions achieved superior antidepressant outcomes as compared to a single infusion with different trajectories of response and remission. Future studies are needed to elucidate neural circuits involved in treatment response to ketamine.

Prognostic Value of Soluble ST2 in the Valsartan Heart Failure Trial

Background—Soluble ST2 (sST2), a biomarker related to inflammation, is associated with outcomes of patients with heart failure. In-depth analyses of the relationship among sST2, changes in sST2, and patient outcomes are reported. Methods and Results—sST2 was measured at baseline (n=1650), 4 months (n=1345), and 12 months (n=1094) in Valsartan Heart Failure Trial. Baseline sST2 averaged 28.7±16.2 ng/mL, significantly (P<0.001) higher in men than women but supranormal in only 9% and 15%, respectively. A continuous relationship between sST2 and the log hazard ratio for outcomes was modeled as 2 linear segments with a significant decrease in the rate of increase in hazard ratios >33.2 ng/mL. Each segment of the sST2 distribution was significantly (P<0.0001) associated with the risks of morbid event, mortality, and hospitalization for heart failure. Only sST2 values <33.2 ng/mL were significantly related to the outcomes when 23 readily available clinical variables including N-terminal probrain natriuretic peptide were included in the Cox regression model. sST2 did not improve discrimination of patient outcomes. Compared with placebo, valsartan significantly (P<0.001) reduced the rate of increase in sST2. Increases in sST2 for 12 months, but not decreases, were significantly associated with subsequent outcomes, independent of clinical variables, sST2, and valsartan treatment. Conclusions—In this study, baseline sST2 was nonlinearly associated with patient outcomes but did not provide substantial prognostic information when added to a clinical prediction model that included N-terminal probrain natriuretic peptide. An increase but not decrease in sST2 was independently associated with outcomes. Additional research is needed to determine whether monitoring ST2 levels can improve patient outcomes.

Associations Between Multidrug Resistance, Plasmid Content, and Virulence Potential Among Extraintestinal Pathogenic and Commensal Escherichia coli from Humans and Poultry

The emergence of plasmid-mediated multidrug resistance (MDR) among enteric bacteria presents a serious challenge to the treatment of bacterial infections in humans and animals. Recent studies suggest that avian Escherichia coli commonly possess the ability to resist multiple antimicrobial agents, and might serve as reservoirs of MDR for human extraintestinal pathogenic Escherichia coli (ExPEC) and commensal E. coli populations. We determined antimicrobial susceptibility profiles for 2202 human and avian E. coli isolates, then sought for associations among resistance profile, plasmid content, virulence factor profile, and phylogenetic group. Avian-source isolates harbored greater proportions of MDR than their human counterparts, and avian ExPEC had higher proportions of MDR than did avian commensal E. coli. MDR was significantly associated with possession of the IncA/C, IncP1-α, IncF, and IncI1 plasmid types. Overall, inferred virulence potential did not correlate with drug susceptibility phenotype. However, certain virulence genes were positively associated with MDR, including ireA, ibeA, fyuA, cvaC, iss, iutA, iha, and afa. According to the total dataset, isolates segregated significantly according to host species and clinical status, thus suggesting that avian and human ExPEC and commensal E. coli represent four distinct populations with limited overlap. These findings suggest that in extraintestinal E. coli, MDR is most commonly associated with plasmids, and that these plasmids are frequently found among avian-source E. coli from poultry production systems.