Clinical Studies on Dark Adaptation: with Particular Reference to Carotid Artery Disease

Purpose: To study dark adaptation in patients with symptomatic carotid artery disease or polycythemia before and after treatment. This necessitated determinations of pupillary changes as such may influence the findings. To determine whether changes in the retinal blood flow in light and darkness occur in healthy humans. Methods: Repeated automatic dark adaptometry was recorded monocularly in 21 consecutive patients scheduled for first-time carotid endarterectomy and in 10 patients with polycythemia. All patients were studied before and after treatment. Analogue investigations were performed in 31 healthy control subjects. The systolic and diastolic blood flow velocities were measured by color Doppler in the ophthalmic and the central retinal arteries in 12 healthy individuals in light and darkness. The pupillary diameter was measured under defined conditions of darkness in all patients and control subjects. Photographic pupillometry was used in 21 patients with carotid artery disease before and after endarterectomy. Results: Dark adaptation was markedly impaired in both categories of patients compared to the control subjects. After carotid endarterectomy in the carotid patients and normalization of the red cell count, hematocrit and hemoglobin in the polycythemic patients, dark adaptation was markedly improved. There was no significant change in dark vision in the control subjects. The results could not be explained by any change in the pupillary diameter. In healthy individuals the systolic and diastolic flow velocities in the central retinal artery were markedly increased in darkness. Conclusions: These findings indicate a sustained but reversible neuronal hypofunction secondary to compromised macro- and microcirculation. Furthermore, the results indicate that darkness is associated with increased blood flow velocity in the central retinal artery, probably reflecting increased metabolic demands by the photoreceptors

EPR Studies of Photosystem II : Characterizing Water Oxidizing Intermediates at Cryogenic Temperatures

The principles of natures own light-driven water splitting catalyst, Photosystem II (PSII), can in the future inspire us to use water as electron and proton source to generate light-driven H2 production. To mimic this challenging step, it is important to understand how the enzyme system can oxidize water. The mechanism of light-driven water oxidation in PSII is in this thesis addressed by EPR spectroscopy. P680+ is a strong oxidant formed by light-oxidation of the chlorophyll species P680 positioned in the center of PSII. The redox active tyrosine-Z (YZ) can reduce P680+ and the YZ• radical is formed. This transient radical is further reduced by the CaMn4-cluster, which is the binding site of the substrate water molecules. In a cyclic process called the S-cycle, this catalytic cluster accumulates four oxidizing equivalents to evolve one molecule of O2 and to oxidize two molecules of water. We can induce the YZ• radical at cryogenic temperatures in the different oxidation states of the catalytic S-cycle and observe this in metalloradical EPR signals. These metalloradical EPR signals are here characterized and used to deduce mechanistic information from the intact PSII. The "double nature" of these spin-spin interaction signals, so called split EPR signals, makes them excellent probes to both YZ oxidation and, when YZ• is present, also to the S-states of the CaMn4-cluster. The metalloradical EPR signals presented here, form a way to study the transient YZ• radical in active PSII that has not been depleted of the catalytic metal cluster. This depleting method that has often been used in the past to study YZ is not representing studies of a mechanistically relevant material. The previously suggested disorder around YZ and accessibility to the bulk can be artifactual properties induced in the mechanistically defect PSII. On the contrary, our observation that proton coupled electron transfer from YZ to the light induced P680+ can occur in a high yield at cryogenic temperatures, suggests a well ordered catalytic site in the protein positioned for optimal performance. The optimized positioning of the redox components found in PSII might be a feature also important to build in an efficient water oxidizing catalyst

Two Eyes Are Better Than One-Binocular Summation of Dark Vision in Healthy Individuals and Patients with Chronic Respiratory Disease

We compared monocular and binocular absolute thresholds of dark adaptation in two separate study populations. Eighteen healthy individuals (Group A) and 13 patients with chronic respiratory insufficiency (Group B) were examined three times each by computerised dark adaptometry with simultaneous but separate recordings from each eye and binocularly. The respiratory patients received oxygen supplement at visits 1 and 3. In Group A, at all three visits, binocular dark adaptation was significantly more sensitive (40.5%) than monocular dark adaptation with either eye. In Group B, at visits 1 and 3, binocular dark adaptation was also significantly more sensitive than monocular dark adaptation (40.5% higher than the right and 47% higher than the left eye). However, in Group B, at visit 2 without oxygen treatment, no significant differences were observed between monocular and binocular sensitivities. Binocular dark vision was superior to monocular dark vision in healthy individuals and in patients with respiratory insufficiency that were provided oxygen supplementation. Furthermore, deficit in oxygen seems to affect binocular summation, perhaps by impaired enhancement in the central nervous system

Muntlighetsprincipen - En utvärdering av svensk rätt mot bakgrund av Europakonventionens krav

I Sverige, liksom i många andra länder, finns sedan länge en tradition av muntlighet vid rättegångsförfarandet. Denna ordning anses utgöra bäst underlag för bevisvärdering och argumentation. I svenska förvaltningsrättsliga mål har denna muntlighetsprincip dock inte fått genomslag, utan i dessa mål är förfarandet normalt skriftligt. Efter andra världskrigets slut var det uppenbart att skyddet för mänskliga rättigheter i Europa måste förstärkas. Europakonventionen tillkom som ett led i denna strävan. Sverige var en av de första stater som ratificerade Europakonventionen, vilket skedde i början av femtiotalet. För svensk del skulle det dock dröja till 1995 innan konventionen inkorporerades med inhemsk rätt. Numera har Europakonventionen status av svensk lag. I Europakonventionens artikel 6 stadgas rätten till en rättvis och offentlig rättegång. I konventionstexten anges inte några uttryckliga krav beträffande rätten till muntlig rättegång. Konventionstexten är mycket generellt formulerad och det är Europadomstolens uppgift att genom sin praxis definiera innehållet i konventionsbestämmelserna. Numera har Europadomstolen tolkat in ett krav på muntligt förfarande i rätten till en rättvis rättegång. Denna praxis är mycket väl sammanhållen, och har dessutom med tiden blivit nyanserad. Med ledning av Europadomstolens domar kan till stor del utläsas var gränserna går för Europakonventionens krav på muntlighet i förfarandet. Kravet är förhållandevis långtgående, och gäller även i situationer då värdet av muntlig förhandling skulle kunna ifrågasättas. Europadomstolen har också angivit vad som gäller beträffande parternas avstående från rätten till muntlighet och vad som gäller beträffande muntlighet i överrätt. Även frågor om vilka krav som kan ställas på en muntlig förhandling har i någon utsträckning besvarats. Dessutom har Europadomstolen angivit att det finns fall då Europakonventionen inte kräver muntlig förhandling. Sverige har under de sista tjugo åren vid ett flertal tillfällen varit svarandestat i Europadomstolen i mål rörande rätten till muntligt förfarande och den mer generella rätten till domstolsprövning. Vid flera tillfällen har Sverige fällts för brott mot dessa mänskliga rättigheter. Detta beror till stor del på den svenska traditionen av skriftlighet i förvaltningsrättsliga mål. De fällande domarna mot Sverige, samt övrig praxis från Europadomstolen, har mot denna bakgrund fått stor betydelse för svensk rättspraxis och vid svenskt lagstiftningsarbete. På detta sätt skall Europakonventionens genomslag i svensk rätt bli större. I nyare svenskt lagstiftningsarbete kan ökande hänsyn till Europakonventionen anses utgöra en trend. En annan trend, som på sätt och vis kan sägas vara motsatt, är en strävan efter ökad snabbhet och flexibilitet, ofta tänkt att tillgodoses genom större utrymme för skriftlighet i förfarandet

Accidental mydriasis from exposure to Angel's trumpet (Datura suaveolens).

PURPOSE: To report clinical findings after accidental instillation into the eye of sap from Angel's trumpet (Datura suaveolens). METHODS: We report findings on seven patients who developed sudden onset of unilateral mydriasis. At least three of them also had ipsilateral cycloplegia and one developed transient tachycardia. RESULTS: The symptoms evolved after ocular exposure to sap from Angel's trumpet, a plant containing natural alkaloids with parasympatholytic properties. Six patients were initially unaware of the cause of their symptoms. In these cases, patient history revealed recent contact with Angel's trumpet. CONCLUSION: Accidental ocular instillation of sap from Angel's trumpet should be noted as a cause of sudden onset of mydriasis in otherwise unaffected patients and also of general symptoms like tachycardia