70 research outputs found
Philip Morris In A Dying Industry - The Creative Destruction Of The Cigarette
This report represents an equity valuation of Philip Morris International Inc.,
one of the leading tobacco firms worldwide. For this, an intrinsic valuation in
form of a DCF model and a relative valuation based on multiples and
transactions was conducted. A target share price of $108.16 was derived which
depicts a Buy recommendation and a total upside potential including a dividend
of 10.79%. The firm was valued especially in light of its shifting business
model and a clear focus towards Risk-Reduced Products going forward.
Additionally, scenario and sensitivity analyses were performed
Vitrifikation von Hornhautlamellen
0\. Titelblatt
1\. Grundlagen und Problemstellung 7
1.1 Anatomie und Physiologie der Hornhaut 7
1.2 Hornhauttransplantation 12
1.3 Hornhautbanken 15
1.4 Routineververfahren der Hornhautkonservierung 16
1.5 Die Gefrierkonservierung der Hornhaut 19
1.6 Ziele dieser Arbeit 35
2\. Material und Methoden 38
2.1 Das Hornhautgewebe 38
2.2 Präparation der Hornhautlamellen 38
2.3 Das Berlin-Mikrokeratom 40
2.4 Vitrifikationsmedium 42
2.5 Einschleusung des Vitrifikationsmediums 43
2.6 Der Gefriergutbehälter 45
2.7 Das Vitrifikationsverfahren 47
2.8 Das Auftauverfahren 49
2.9 Ausschleusung des Vitrifikationsmediums 49
2.10 Die Organkultur 50
2.11 Die Vitalfärbung 51
2.12 Fotodokumentation und Endothelzellanalyse 53
2.13 Ăśbersicht ĂĽber den gesamten Verfahrensablauf 54
3\. Ergebnisse 56
3.1 Endothelzellanalyse unbehandelter Hornhautlamellen 56
3.2 Verträglichkeit der Oberfläche des Gefriergutbehälters mit dem
Hornhautendothel 58
3.3 Vitrifikation von Hornhautlamellen bei -140°C 59
3.4 Fotografische Dokumentation der Devitrifikation bei Raumtemperatur 66
3.5 Endothelzellanalyse nach erfolgter Vitrifikation bei -196°C und Erwärmung
im Wasserbad 67
3.6 Toleranz des Hornhautendothels gegenĂĽber dem verwendeten
Organkulturmedium 69
3.7 Toleranz des Hornhautendothels gegenĂĽber der verwendeten
Vitrifikationslösung 71
4\. Diskussion 76
4.1 Erzielte Fortschritte 76
4.2 Vorteile und Perspektiven der Vitrifikation 79
4.3 Toxizität der Kryoprotektoren 80
4.4 Devitrifikation 82
4.5 BerĂĽcksichtigung der post-mortem-Zeit 84
4.6 Aussagekraft der Endothelzellanalyse 84
4.7 Vorschläge für Untersuchungen zur weiteren Verbesserung des
Vitrifikationsverfahrens 85
5\. Zusammenfassung 88
6\. Literaturverzeichnis 90In the work presented here it has been possible for the first time to carry
out the vitrification of corneal lamellae without there being any ice
formation or cracking of the frozen product. The basis for this success were
three modifications of the vitrification procedure: (1) Instead of using
corneoscleral discs which were previously used for freezing experiments,
posterior corneal lamellae were used in this investigation. The resulting
simultaneous volume reduction led to a more rapid and controllable heat
exchange between the corneal tissue and the coolant. (2) By using frozen
product packaging which was very thin-walled, transparent and Teflon-coated
(Kapton / Teflon peel pouch) it was possible to achieve direct contact between
the cornea and the frozen product packaging without endothelial cell damage,
whereby the heat exchange was likewise optimized. (3) The flash freezing to
-140°C which promotes vitrification was achieved by means of a newly developed
freezing device using methylcyclopentane and propane as coolants. Since,
despite the successful vitrification, only a maximum of 10% of the endothelial
cells were vital after heating, the toxicity of the cryoprotectors which was
determined to be the cause, and the devitrification which occurred during the
heating process, should be further examined.In der hier vorgestellten Arbeit ist es erstmals gelungen, Hornhautlamellen zu
vitrifizieren, ohne daĂź es dabei zu einer Eis- oder RiĂźbildung im Gefriergut
gekommen ist. Grundlage fĂĽr diesen Erfolg waren drei Modifikationen des
Vitrifikationsverfahrens. (1) Statt der bislang fĂĽr Gefrierversuche
verwendeten Korneoskleralscheiben wurden in dieser Untersuchung hintere
Hornhautlamellen verwendet. Die damit einhergehende Volumenreduktion bedingte
einen schnelleren und besser zu kontrollierenden Wärmeaustausch zwischen
Hornhautgewebe und KĂĽhlmedium. (2) Durch Verwendung eines sehr dĂĽnnwandigen,
transparenten und teflonbeschichteten Gefriergutträgers (Kapton/Teflon Peel
Pouch) konnte ein direkter Kontakt von Hornhaut und Gefriergutträger ohne
Endothelzellschädigung erreicht werden, wodurch ebenfalls der Wärmeaustausch
optimiert wurde. (3) Die für die Vitrifikation förderliche schockartige
Abkühlung bis -140° C wurde mit einer neu entwickelten Einfriervorrichtung
unter Verwendung von Methylcyclopentan und Propan als KĂĽhlmittel erreicht. Da
trotz erfolgreicher Vitrifikation nur maximal 10% der Endothelzellen nach dem
Erwärmen vital waren, sollte die dafür als ursächlich ermittelte Toxizität der
Kryoprotektoren und die während des Aufwärmvorganges auftretende
Devitrifikation weiter untersucht werden
First experience with the wearable cardioverter defibrillator in the Netherlands
The implantable cardioverter defibrillator (ICD) has significantly improved survival in patients with an increased risk of sudden cardiac death (SCD). The wearable cardioverter defibrillator (WCD) is an alternative to the ICD in patients with a transient ICD indication or those in whom an ICD temporarily cannot be implanted. We describe here the technical details of the WCD and report three patients who were treated with a WCD in an outpatient setting. The WCD allowed the cardiac condition of two patients to improve to such an extent that permanent ICD implantation was deemed unnecessary. This new form of therapy may result in significant cost reduction, avoidance of unnecessary ICD implantation, and increased patient satisfaction
Refractive change in the adult rabbit eye after corneal relaxation with the femtosecond laser
In vivo confocal microscopy and histopathology of the conjunctiva in trachomatous scarring and normal tissue: a systematic comparison.
AIM: To compare in vivo confocal microscopy (IVCM) with the histopathological examination of tissue and cellular changes in normal and diseased conjunctiva. METHODS: Participants underwent clinical examination and IVCM of the tarsal conjunctiva. A biopsy of the upper tarsal conjunctiva was collected and stained with tinctorial stains and by immunohistochemical staining for CD45 and CD83. Connective tissue scarring, inflammatory cell density and the presence of dendritiform cells were quantitatively assessed in a masked manner by both IVCM and histological assessments for comparative analysis. RESULTS: Thirty-four participants with severe trachomatous conjunctival scarring and 33 participants with healthy conjunctiva were recruited. The IVCM connective tissue scarring score was strongly associated with the histological grading of scarring (p<0.001). There was limited evidence of an association between the IVCM inflammatory cell infiltrate and the histological inflammatory cell grade (p=0.05). We did not find any evidence to support the hypothesis that dendritiform cells seen with IVCM are mature, conventional dendritic cells. CONCLUSIONS: The results show that IVCM can be used to robustly quantitate connective tissue scarring and also has a role in measuring the inflammatory cell infiltrate. The discordance between IVCM dendritiform cells and immunohistochemical dendritic cells may be a result of study limitations or may be because these dendritiform structures represent another cell type, such as fibroblasts, rather than dendritic cells
Corneal first-surface aberration analysis of biomechanical effects of astigmatic keratotomy and a microkeratome cut after penetrating keratoplasty
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