19 research outputs found
Termination of Ventricular Tachycardia with Antitachycardia Pacing after Ineffective Shock Therapy in an ICD Recipient with Hypertrophic Cardiomyopathy
Implantable Cardioverter Defibrillator (ICD) implantation is the only established therapy for primary or secondary prevention of sudden cardiac death in patients with Hypertrophic Cardiomyopathy (HCM). Ineffectiveness of shock therapy for the termination of potentially fatal ventricular arrhythmias in ICD recipients is rare in the presence of appropriate arrhythmia detection by the device. We report the case of a 48-year-old woman with HCM and a single chamber ICD, who received five inefficient high-energy (35 Joules) shocks for the termination of an appropriately detected episode of Ventricular Tachycardia (VT). The episode was safely terminated with a subsequent application of Antitachycardia Pacing (ATP) by the device. At the following ICD control, an acceptable defibrillation threshold was detected
Remote monitoring and clinical outcomes:details on information flow and workflow in the IN-TIME study
Comprehensive molecular, genomic and phenotypic analysis of a major clone of Enterococcus faecalis MLST ST40
Methoden zur Endotoxinbestimmung auf Filtern von Klimaanlagen
Titelblatt, Inhaltsverzeichnis, Danksagung
1 Introduction 9
1.1 Endotoxin 9
1.2 Measurement of Endotoxin 10
1.3 Study Aims 14
2 Materials and Methods 15
2.1 Main Investigations 15
2.2 Preliminary Investigations 29
3 Results 32
3.1 Main Investigations 32
3.2 Preliminary Investigations 44
4 Discussion 51
4.1 Material under Investigation 51
4.2 Suspension for Inoculation of the Filters 52
4.3 Extraction Procedure 53
4.4 Assay Work 56
4.5 Looking at Raw Data 59
4.6 Analysis of Data 61
4.7 Endotoxin Limits 66
4.8 Costs 67
4.9 Conclusions 67
5 Summary 69
6 Appendix: Tables and Figures 72
7 References 85
9 Curriculum Vitae 92Endotoxin, a lipopolysaccharide component of the cell wall of gram negative
bacteria, may play a major role in the development of the Sick Building
Syndrome. Filter of heating-, ventilation- and air-conditioning systems can
represent possible source of endotoxin contamination of indoor air.
Measurements of endotoxin on filters cannot be compared between investigators
because of different retrieving conditions. This study was inaugurated to
determine the most effective method and their recovery rate for endotoxin
retrieval. Determination of endotoxin was performed with a biological test
(Limulus Amoebocyte Lysate). In this investigation the most common filter
types of HVAC systems used in Germany were examined. These are cellulose-,
glass- and synthetic fiber filters that were inoculated with four different
types of endotoxins LPS in two different activities, Escherichia coli,
Pseudomonas aeruginosa and dust out of an HVAC system). Filters were brand new
to prevent pre-contamination because of impracticable detoxification of the
material. Different contamination fluids were used to imitate most realistic
(dust) circumstances on one and to perform most standardized (LPS) conditions
on the other hand. To prepare endotoxin suspension by extracting the
inoculated filters these were shaken or sonicated in a Tween 20 or
Triethylamine buffer (TAP) solution. A total number of 360 samples were
measured. In extensive preinvestigations optimal settings and conditions were
drawn up. Detoxification with -radiation was checked, improvement of the test
system, times of extraction and optimal concentration of solution media were
worked out. Strict prevention of endotoxin contamination and a partly blinding
were performed. For statistical evaluation descriptive data and data
calculated with ?Generalized Linear Models? were shown. Because of
inhomogeneous distribution of Pseudomonas aeruginosa endotoxin contaminated
filters and its enormous influence on the results this strain was determined
separately. When we analyzed data of all contaminations except Pseudomonas
aeruginosa glass fiber filter showed a deviation from 100% recovery rate of
2.6%, cellulose fiber of 276.2% and synthetic fiber filter with 51.0%.
Sonication revealed as best solution media with 18.9% difference ahead of
shaking with 190.8%. TAP was supreme of Tween 20 with 53.3% difference and
160.6%, respectively. As expected LPS, it represents the most standardized
endotoxin, showed best recovery of all examined endotoxins with a mean square
fractional difference (MSFD) (2.1.8.2) of 70.1% for the activity of 200 EU and
48 % for 2,000 EU, respectively. Looking at the most standardized conditions
with contamination of well defined endotoxin (LPS 2,000 EU) and a combination
of the extraction method it was shown for cellulose fiber filter: Best
extraction is performed with sonication in TAP with recovery of - 6.1% and an
MSFD of 14.1%. In worst case if sonicated in Tween difference will present
with -91.4% and an MSFD of 91.6%. Extraction of glass fiber filter is best if
shaken in TAP (Figure 5 1) with MSFD of 19.2% and a difference of -16.7%.
Almost as good as was the removal with sonication and TAP is with MSFD of
29.2% and an overestimation of 27.9%. Synthetic fiber filter revealed almost
same results for all four combinations. Smallest difference for Tween and
sonication with an overestimation of 5.5% is shown. MSFD for these
combinations was between 20.3% and 24.1%. When calculating data with
?Generalized Linear Models? it revealed no significant differences for any
constellation. This might be due to differences of sample conditions and their
relatively small number of five samples per unique method. The extraction
methods are slightly but not statistical significant (n.s.) different
(p=0.323). Sonication showed a mean difference of 2 (CI95 ?370 to 374)
compared with the TA and was better than shaking which showed a mean
difference of 263 (CI95 ?109 to 635). Solution media (n.s.) (p=0.327). TAP
showed a mean difference of 3 (CI95 ?369 to 375) from the TA and was more
potent than Tween 20 that showed a mean difference of 262 (CI95 -110 to 634).
Type of filter (n.s.) revealed a ?p? of 0.375. Glass fiber filters showed a
mean difference of 0.5 (CI95 ?455 to 456) that was better than synthetic fiber
filters that showed a mean difference of 2.6 (CI95 ?453 to 458) and was better
than cellulose fiber filters which showed a mean difference of 394 (CI95 ?62
to 850). The contamination fluids reported a ?p? of 0.393 and were not
statistical significant. LPS 200 showed a mean difference of 0.5 (CI95 ?525.8
to 526.8) and was not as close as LPS 2,000 that showed a mean difference of
0.2 (CI95 ?526.1 to 526.6) which was better than Dust that showed 1.0 for mean
difference (CI95 ?525 to 527) and Escherichia coli which showed 528 (CI95 of 2
to1,054) for mean difference. Although using a sophisticated statistical
analysis, precise preparation of sample contamination with well defined
endotoxin solutions, sample extraction and accurate assay work with partly
blinding it was not possible to find one significant, most reliable and
precise method for endotoxin recovery on HVAC systems filter. There were major
differences between filter material and types of endotoxin. Tendencies of
better methods were observed and need to be confirmed in larger extent.
Especially the recovery rate has to be determined prior to the investigation
and should be labeled because of its major impact for the results. A
preinvestigation study of the interesting filter type with LPS contamination
and approximately 50 reiterations could attain the recovery rate. Most
important differences can arise if the standard curve is not prepared with the
same dilution media like used for endotoxin recovery. As a general
recommendation it is mentioned to use endotoxin free material wherever
possible, to check water for absence of endotoxin, to perform very precise
work, to verify nonattendance of interference for every single probe, to use
same lot number of test kits for all tests and to do the assay work
immediately following the extraction. Especially the samples should be dried
after sampling when immediately extraction and determination is not possible,
because of uncertain recovery for suspended samples.Endotoxin, eine Lipopolysaccharid-Komponente (LPS) der Zellwand gram-negativer
Bakterien, kann eine Rolle in der Entwicklung des Sick Building Syndrome
spielen. Filter von Klimaanlagen kommen als potentielle Quelle für Endotoxin-
Kontamination der Innenluft in Frage. Die Messergebnisse zwischen Untersuchern
sind nicht vergleichbar, weil keine standardisierte Methode vorhanden ist. In
dieser Studie werden die effektivsten Methoden beschrieben zur Widerfindung
von Endotoxinen auf Filtern von Klimaanlagen, mit den jeweiligen
Widerfindungsraten. Die Bestimmung der Endotoxine erfolgte mit einem
biologischen Test (Limulus Amoebocyte Lysate). Es wurden die am häufigsten
verwendeten Filterarten in deutschen Klimaanlagen untersucht. Diese sind
Zellulose-, Glass- und Synthesefaser Filter. Sie wurden mit vier verschiedenen
Arten von Endotoxinen (Escherichia coli, Pseudomonas aeruginosa, gereinigtes
Standard Endotoxin und Staub aus eine Klimaanlage) in zwei verschiedenen
Konzentrationen beimpft. Das Filtermaterial wurde aus der Herstellung
entnommen und vor Kontamination geschützt, da eine Detoxifikation nicht
praktikabel ist. Unterschiedliche Kontaminationen wurden verwendet um
möglichst realistische (Staub) und möglichst standardisierte (LPS)
Versuchsbedingungen zu erzielen. Die beimpften Filter wurden in zwei
Extraktionslösungen (Tween 20 oder Triethylamine buffer (TAP)) ausgeschüttelt
oder mit einem Ultraschallbad behandelt. Eine Gesamtzahl von 360 Proben wurden
gemessen. In umfangreichen Voruntersuchungen wurden die optimalen
Untersuchungsbedingungen ermittelt. Detoxifikation mit Gamma-Stahlung wurde
untersucht, Verbesserungen des Testsystems erarbeitet, sowie optimale Zeiten
für die Extraktion bestimmt. Strikte Vermeidung der Kontamination mit
Endotoxinen und eine teilweise Verblindung der Untersuchung wurden
durchgeführt. Die statistische Auswertung erfolgte als beschreibender und
berechneter Teil nach "Generalized Linear Models". Wegen inhomogener
Verteilung der Messwerte für die Kontamination mit Pseudomonas aeruginosa
Endotoxin erfolgte die statistische Auswertung für diesen Keim separat. Obwohl
eine ausgeklügelte statistische Methode, präzise Präparation der Proben und
die Kontamination mit gut definierten Endotoxin-Lösungen durchgeführt wurde,
war es nicht möglich signifikante Unterschiede zwischen den Methoden zu
erarbeiten. Es wurden größere Unterschiede zwischen den Filtermaterialien und
Arten von Endotoxin festgestellt. Tendenzen für bessere Methoden wurden
beobachtet und müssen in größeren Stichproben verifiziert werden. Vor einer
Untersuchung müssen insbesondere die Wiederfindungsraten für das jeweilige
Verfahren ermittelt und für die Vergleichbarkeit angegeben werden. Besondere
Wichtigkeit hat die Anfertigung der Standardkurve, welche mit dem gleichen
Lösungsmittel, wie die Extraktion, geschehen sollte. Als allgemeine
Empfehlungen für die Endotoxinbestimmung auf Filtermaterialien lassen sich
folgende Punkte anführen. Es sollte unter allen Umständen Endotoxin freies
Material Verwendung finden. Das Wasser zur Verdünnung ist auf Endotoxine zu
untersuchen. Störfaktoren für den biologischen Test müssen ausgeschlossen
sein. Es sollten alle Bestimmungen mit der selben Charge des LAL-Reagenz
durchgeführt werden
Crystallization and Preliminary X-ray Studies of Lipase from Geotrichum candidum
Wehave succeeded in the production of new crystals of lipase from Geotrichum candidum which
were suitable for a refined X-ray analysis. First measurements proved the lattice constant and space
group to be similar to that reported by Hata et al. /1/. However, these crystals can be analyzed
without any cross-linking. This should enable a higher resolution for the structure determination of
the lipase from Geotrichum candidum.
Inhibition experiments with this lipase proved metal ions, iodine and p-chloromercuribenzoate
to effect the enzyme activity. Metal ions inactivated lipase at a 1000-fold excess and in the order
of Ag*>Hg’* >Co**>Zn**. In contrast, I, and p-chloromercuribenzoate modified lipase from
Geotrichum candidum in stoichiometric amounts. These modified as well as a deglycosylated lipase
could becrystallized. Such crystals ofslightly modified lipases offer the chance of analyzing further
details of the lipase structure, e.g. the influence of the glycosylation on the tertiary structure, and
they are an alternative approach to high quality crystals