Fluid biomarker agreement and interrelation in dementia due to Alzheimer's disease.

The cerebrospinal fluid (CSF) levels of ß-amyloid 42, total tau, and phosphorylated tau 181 are supposed to be all continuously abnormal in dementia due to Alzheimer's disease (AD), being the most advanced disease stage. The aim of the present study, which included a monocentric and a multicentric sample (N = 119 and 178, respectively), was to investigate the degree of CSF biomarker agreement and interrelation in AD dementia. Based on previously published cut-off values, biomarker values were categorized as positive or negative for AD (dichotomization strategy) and as either positive, negative, or borderline (trichotomization strategy). The statistical analyses relied on distance correlation analysis and kappa (k) statistics. Poor agreement (k < 0.4) and low interrelations between the studied biomarkers were detected in all cases with the exception of the interrelation between the markers total tau and phosphorylated tau 181, especially in the monocentric sample. Interestingly, lower interrelation and agreement degrees were observed in carriers of the Apolipoprotein E ε4 allele compared to non-carriers. The clinical phenotype currently referred to as "AD dementia" is characterized by an inhomogeneous CSF biomarker profile, possibly mirroring the complex genesis of AD-typical dementia symptoms and pointing to the necessity of shedding more light on the hypothesis of biomarker stability over time in symptomatic AD.

Mapping CSF biomarker profiles onto NIA-AA guidelines for Alzheimer's disease.

The National Institute on Aging-Alzheimer's Association (NIA-AA) guidelines for Alzheimer's disease (AD) propose the categorization of individuals according to their biomarker constellation. Though the NIA-AA criteria for preclinical AD and AD dementia have already been applied in conjunction with imaging AD biomarkers, the application of the criteria using comprehensive cerebrospinal fluid (CSF) biomarker information has not been thoroughly studied yet. The study included a monocentric cohort with healthy (N = 41) and disease (N = 22) controls and patients with AD dementia (N = 119), and a multicentric sample with healthy controls (N = 116) and patients with AD dementia (N = 102). The CSF biomarkers ß-amyloid 1-42, total tau, and phosphorylated tau at threonine 181 were measured with commercially available assays. Biomarker values were trichotomized into positive for AD, negative, or borderline. In controls the presence of normal CSF profiles varied between 13.6 and 25.4 % across the studied groups, while up to 8.6 % of them had abnormal CSF biomarkers. In 40.3-52.9 % of patients with AD dementia, a typical CSF profile for AD was detected. Approximately 40 % of the potential biomarker constellations are not considered in the NIA-AA guidelines, and more than 40 % of participants could not be classified into the NIA-AA categories with distinct biomarker constellations. Here, a refined scheme covering all potential biomarker constellations is proposed. These results enrich the discussion on the NIA-AA guidelines and point to a discordance between clinical symptomatology and CSF biomarkers even in patients with full-blown AD dementia, who are supposed to have a clearly positive for AD neurochemical profile.

Gastrointestinal torsions and intussusception in northern koalas (Phascolarctos cinereus) at San Diego Zoo (1976-2012).

The recent classification as threatened status of the northern koala (Phascolarctos cinereus) by the Australian Government highlights the importance of the conservation and health management of this iconic Australian marsupial. This case series describes gastrointestinal torsion and intussusception in six northern koalas (three males, three females, 2-11 yr old) at the San Diego Zoo from 1976 to 2012. Two koalas died shortly after presentation. Diagnoses of ileocecal intussusception, resulting from enteritis in one case and cecal torsion in the other, were made at postmortem examination. One koala died 4 days after an exploratory laparotomy, with negative findings, and an acute double colonic intussusception was diagnosed at postmortem examination. Two small intestinal mesenteric torsion and one proximal colon mesenteric torsion cases were successfully corrected surgically. In the case of colonic mesenteric torsion, the koala had recurrent clinical signs 2 wk later, and a second surgery requiring resection and anastomosis of ischemic jejunum was performed, with the koala dying shortly afterward. One koala with small intestinal torsion had a recurrence of torsion 22 mo later and subsequently died. The koala with the second case of small intestinal torsion remains alive 14 mo postsurgical correction. All six koalas presented with signs of colic that included anorexia, lethargy, depression, acute abdominal distension, abdominal stretching, decreased fecal output, open-mouth gasping, or a combination of symptoms. Abdominal radiographs may show stacked gastrointestinal linear gas patterns and contrast stasis. Prevalence of torsion and intussusception is low at this institution (2%), although recurrence in individuals is common (50%) and overall survival is poor (83%), which emphasizes the importance of timely recognition, surgical correction, and postoperative management. While inciting etiologies were unable to be determined in these cases, monitoring generalized gastrointestinal health and differing Eucalyptus sp. effects on individual koala's gastrointestinal function, parasite control, and stress minimization through standardized husbandry practices are likely important.

Extracranial ultrasound following mechanical thrombectomy in patients with acute stroke.

BACKGROUND AND PURPOSE: Mechanical thrombectomy (MT) is standard care for patients suffering from an ischemic stroke due to a large vessel occlusion. Immediate and follow-up transcranial ultrasound examinations after MT were shown to have a diagnostic benefit. However, it is unclear whether repeated extracranial ultrasound after MT has an additional diagnostic yield, that is, depicts new findings. METHODS: Retrospectively, from our prospective database we identified all patients after MT who presented for a follow-up examination between January 2017 and March 2020 and who had received an ultrasound examination after MT and at follow-up. Clinical data were extracted from our database. Ultrasound images of all patients were revisited to identify new findings at follow-up compared to examination after MT. RESULTS: Ninety-one patients were identified appropriate for further analysis, with a mean age of 67.8 ± 16 years. Median National Institute of Health Stroke Scale at admission was 11 ± 8.5 points. At baseline ultrasound, 18 patients (19.8%) had no atherosclerotic alterations and 73 patients (82.2%) had a plaque burden of ≥1 plaque. During follow-up, in 5 patients (5.5%) a pathological finding presented in first examination evolved dynamically, that is, normalized. Vessel status of all other patients was stable, especially, in no patient a new relevant pathological finding occurred. CONCLUSIONS: Although sonographic normalization of pathologic findings was observed, pathologic new findings were not detected during follow-up. This study provides first data for a discussion of the role of ultrasound in a structured stroke care after MT. However, larger studies are required to improve the understanding.

Field monitoring data on a residential exhaust air heat pump system (air-to-air heat pump).

This data article presents the raw data used in the article "Experimental and analytical evaluation of exhaust air heat pumps in ventilation-based heating systems" [1]. The data set contains measurement results of a field monitoring on a residential exhaust air heat pump system (air-to-air heat pump) in Germany. This data could be used to investigate the dynamic behavior and performance of the exhaust air heat pump systems. The data set contains air temperature and humidity of all four sides of the heat pump unit. Moreover, the electrical consumption of the unit and the dynamic pressure difference on the exhaust side (as indication of the air volume rate) could be also found in the data set.

Conflicting cerebrospinal fluid biomarkers and progression to dementia due to Alzheimer's disease.

BACKGROUND: According to new diagnostic guidelines for Alzheimer's disease (AD), biomarkers enable estimation of the individual likelihood of underlying AD pathophysiology and the associated risk of progression to AD dementia for patients with mild cognitive impairment (MCI). Nonetheless, how conflicting biomarker constellations affect the progression risk is still elusive. The present study explored the impact of different cerebrospinal fluid (CSF) biomarker constellations on the progression risk of MCI patients. METHODS: A multicentre cohort of 469 patients with MCI and available CSF biomarker results and clinical follow-up data was considered. Biomarker values were categorized as positive for AD, negative or borderline. Progression risk differences between patients with different constellations of total Tau (t-Tau), phosphorylated Tau at threonine 181 (p-Tau) and amyloid-beta 1-42 (Aß42) were studied. Group comparison analyses and Cox regression models were employed. RESULTS: Patients with all biomarkers positive for AD (N = 145) had the highest hazard for progression to dementia due to AD, whilst patients with no positive biomarkers (N = 111) had the lowest. The risk of patients with only abnormal p-Tau and/or t-Tau (N = 49) or with positive Aß42 in combination with positive t-Tau or p-Tau (N = 119) is significantly lower than that of patients with all biomarkers positive. CONCLUSIONS: The risk of progression to dementia due to AD differs between patients with different CSF biomarker constellations.