Transmission mode affects the population genetic structure of Daphnia parasites

Parasite life cycle variation can shape parasite evolution, by predisposing them towards different population genetic structures. We compared the population genetic structure of two co-occurring parasite species of Daphnia, to collect evidence for their expected transmission modes. The ichthyosporean Caullerya mesnili has a direct life cycle, whereas the microsporidian Berwaldia schaefernai is hypothesized to require passage through a secondary host. The parasites were collected from three geographically isolated Daphnia populations. The nucleotide variation in the internal transcribed spacer (ITS) region was assessed at the within-individual, within-population and among-population levels, using amova. We detected significant partitioning at all levels, except for a lack of among-population variation in Berwaldia. This was confirmed by neighbour-joining and principal component analyses; Caullerya populations were distinct from each other, while there was much overlap among parasite isolates representing different populations of Berwaldia. This all implies a higher amount of gene flow for Berwaldia, consistent with the hypothesized transmission mode.

Inorganic membranes for hydrogen production and purification: A critical review and perspective

Hydrogen as a high-quality and clean energy carrier has attracted renewed and ever-increasing attention around the world in recent years, mainly due to developments in fuel cells and environmental pressures including climate change issues. In thermochemical processes for hydrogen production from fossil fuels, separation and purification is a critical technology. Where water-gas shift reaction is involved for converting the carbon monoxide to hydrogen, membrane reactors show great promises for shifting the equilibrium. Membranes are also important to the subsequent purification of hydrogen. For hydrogen production and purification, there are generally two classes of membranes both being inorganic: dense phase metal and metal alloys, and porous ceramic membranes. Porous ceramic membranes are normally prepared by sol-gel or hydrothermal methods, and have high stability and durability in high temperature, harsh impurity and hydrothermal environments. In particular, microporous membranes show promises in water gas shift reaction at higher temperatures. In this article, we review the recent advances in both dense phase metal and porous ceramic membranes, and compare their separation properties and performance in membrane reactor systems. The preparation, characterization and permeation of the various membranes will be presented and discussed. We also aim to examine the critical issues in these membranes with respect to the technical and economical advantages and disadvantages. Discussions will also be made on the relevance and importance of membrane technology to the new generation of zero-emission power technologies.

Korneale Wundheilungsreaktionen nach hyperoper PRK und LASIK

BACKGROUND

The purpose of this study was to investigate the influence of different postoperative treatments on the wound healing reaction in the anterior stroma after PRK and in the interface area after LASIK.

METHODS

Seventy-two corneal buttons of refractively treated rabbit eyes underwent different postoperative eyedrop regimens with antibiotics and/or steroids or additional UV-B irradiation. Morphological and immunohistological investigations were performed 6 months postoperatively by light and transmission electron microscopy.

RESULTS

PRK eyes showed interdigitations between the epithelia and the anterior stroma. LASIK-treated eyes showed only minor changes between epithelia and stroma in the incisional region. Only a slight increase in deposits of fibrillar extracellular matrix components were detectable in the interface region.

CONCLUSIONS

The clinically important problem of haze after PRK is caused by the interdigitations between epithelia and anterior stroma. The delicate wound healing reactions in the interface region in LASIK eyes corresponded to the clinically visible minor changes in these corneas.

Ergebnisse der wellenfrontgest�tzten LASIK

BACKGROUND

Wavefront-guided LASIK procedures provide patients with customized corneal treatments. The computer ablation profiles correct both spherical and/or cylindrical errors of refraction and aberrations up to the fifth order.

METHODS

We performed wavefront-guided LASIK treatments on 62 patients using the Keracor 217 Z. The spherical equivalent was -6.11 +/-2.29 D on the average. Data collected for 3 months were evaluated to determine the predictability, efficacy, stability, and safety of the refractive procedure.

RESULTS

We found good predictability of the refractive result after correcting -1 to -6 D of myopia. Beyond -7 D there were over- and undercorrections of +/-2 D in 10% of the procedures. A UCVA of 0.8 or better was observed in 53% of the patients 3 months postoperatively, and 75% of the patients reached a BCVA of 0.8 or better. After 3 months 6% lost 2 lines, 22% lost 1 line, 22% of the patients gained 1-2 lines, and BCVA remained unchanged in 55%. The fluctuation of the refraction was about -0.23 D during the first 3 postoperative months.

CONCLUSIONS

The low and middle range of myopia can be corrected very accurately using the wavefront technology. Higher degrees of myopia face both under- and overcorrections. Postoperative refractions become stable very quickly. However, the visual acuity changes even 6 months postoperatively. From our point of view, wavefront correction by LASIK should be more reliable in terms of centration, accuracy, and standardization to get better results.

[Recurrent corneal erosion after mechanical trauma. Results of transepithelial phototherapeutic keratectomy]

BACKGROUND

Recurrent corneal erosion is a common clinical disorder characterised by repeated spontaneous breakdown of the corneal epithelium. The pathomechanism is due to abnormalities of the adhesion complex between the corneal epithelium and the stroma. In addition to local medical treatment, bandage lenses, debridement and anterior stromal puncture, patients can also be treated by excimer laser phototherapeutic keratectomy.

METHODS

We present a series of 45 eyes where a transepithelial therapeutic excimer photoablation (t-PTK) was carried out after recurrent erosions caused by mechanical trauma. We used the flying spot excimer laser Technolas 217-C (Bausch & Lomb Surgical) and the scanning spot laser MEL70 (Aesculap Meditec). Treatment was performed in the relapse-free period. The zone of ablation measured 6-9 mm and the ablation depth 10-30 microns. The mean follow-up period was 7 months (range 3-22).

RESULTS

After the first t-PTK treatment, 41 eyes remained without a relapse, but 8 patients had persistent symptoms, 4 of which had a new epithelial breakdown and in 2 patients a second t-PTK had to be carried out.

CONCLUSIONS

T-PTK appears to be a safe and effective procedure for treatment of recurrent corneal erosion. However, relative contraindications, such as a previous chemical burn, must be taken into account.

Hydrophobicity of templated silica xerogels for molecular sieving applications

Silica xerogels were prepared by a sol-gel process catalyzed by acid with tetraethylorthosilicate, and using an organic covalent ligand template (methyltriethoxysilane) or a noncovalent template C6 surfactant (triethylhexylammonium bromide). The influence of hydrotreatment on the structure of templated xerogels is examined in terms of surface area, micropore volume, average pore size, and pore size distribution, and compared against a blank xerogel (nontemplated). The role of surface functional groups was evaluated using 29Si nuclear magnetic resonance. The structural integrity of the xerogel was maintained to a large extent in samples that had a high contribution of Q4 species (siloxane groups). Xerogel matrix densification occurred when there was a large concentration of Q3 and Q2 species (silanol groups), which also were responsible for increased hydrophilicity. The templated xerogels resulted in up to a 25% concentration of methyl functional groups (T3 and T2 species), leading to hydrophobic xerogels. The best results in terms of structural integrity and hydrophobicity were obtained with templated xerogels prepared with the C6 surfactant. The results in this study suggest that surfactant-enhanced condensation reactions lead to structures with a high contribution of Q4 groups, which are not susceptible to water attack, but are strong enough to oppose matrix densification during rehydration.

Short-term visual rehabilitation after LASIK

PURPOSE

To determine the early course of visual recovery after LASIK for myopia.

METHODS

In eight eyes visual acuity, both uncorrected and corrected, objective refraction, topography and contrast sensitivity were measured six times during the first day, twice daily for two days and after 1 week.

RESULTS

Patients experienced considerable variability in achieving best corrected visual acuity. 80% of patients already had uncorrected visual acuity of 0.5 or better 1 day after surgery. By the 16th hour 97% of preoperative best spectacle-corrected visual acuity was achieved. The mean radius of anterior corneal curvature was already relatively constant after 3 h. After that the corneal topography was fairly stable.

CONCLUSIONS

Vision recovers rapidly after LASIK. Visual rehabilitation was reached after 16 h in most cases. Mesopic vision, however, was reduced after LASIK.

[Specular microscopy follow-up of endophthalmitis after cataract operation]

INTRODUCTION

Since the first reports of specular microscopic photographs in vivo of the corneal endothelium, endophthalmitis is said to damage endothelial cells irreversibly.

PATIENTS AND METHOD

We controlled 29 eyes 1 to 10 years after endophthalmitis following cataract surgery using specular microscopy. We tried to find out, if endophthalmitis leads to significant endothelial damage and we wanted to describe the in-vivo-cytological follow-up of the implanted lenses.

RESULTS

Endothelial cell-density of the eyes with endophthalmitis (n = 29) was 2733/mm2 (+/- 680). In those eyes receiving cataract-surgery without endophthalmitis in the fellow eye (n = 14), the endothelial density was 2851/mm2 (+/- 360). If the fellow eye has had no cataract surgery (n = 13), cell density was 3110/mm2 (+/- 750). Hypopyon-iritis after cataract-surgery did not decrease endothelial cell count significantly more than cataract-surgery without hypopyon-iritis (p > 0.05). At the last control at least one year after surgery, 36% of all IOLs were free of any cellular deposits. There was no case of a foreign-body-reaction.

CONCLUSION

In our patients, postoperative endophthalmitis has not led to significant endothelial damage. In none of our patients, endophthalmitis has led to chronic foreign-body reaction against the implant or to granulomatous uveitis. Specular microscopy of the corneal endothelium and of the implanted lens may help to differentiate in the case of postoperative inflammation between an infection and a foreign-body-reaction. In the case of a sterile foreign-body-reaction, there are no inflammatory cells on the endothelium or in the anterior chamber.

[Spontaneous hematocornea after keratitis of various etiology]

BACKGROUND

Corneal blood staining may occur as a serious complication of persisting hyphema. In our two cases the corneal blood staining is a result of direct bleeding in the corneal stroma.

HISTORY AND SIGNS

A female patient presented with a corneal blood staining through rupture of reopened vessels in interstitial keratitis of congenital syphilis after physical effort with high blood pressure. The second patient presented with a blood staining caused by a vessel errosion after corneal ulceration.

THERAPY AND OUTCOME

The clearing of the blood staining is thought to be a result of the phagocytic action of the keratocytes and from a diffusion of hemoglobin into the conjunctival circulation and the anterior chamber (2). The therapeutic efforts are directed toward prevention of corneal blood staining. At the first sign of microscopic blood staining of the cornea a surgical evacuation of hyphema is necessary. In our two cases there wasn't a hyphema, so it was only possible to treated the corneal ulcer, entropion and systemic hypertension.

CONCLUSION

The clinician has to wait for a spontaneous clearing, although it may take 2 or 3 years or more. In this case a penetrating keratoplasty is indicated.

[Consensual inflammatory reaction in chemical eye burn of the rabbit eye]

BACKGROUND

Consensual ocular response has been known to occur following intracranial stimulation of the trigeminal nerve, intracameral injection of prostaglandins and other substances, after paracentesis and contusio bulbi.

MATERIAL AND METHOD

We have examined the prostacyclin formation in both eyes after experimental alcali burn (0.25 mo/l NaOH) on 30 rabbits with ELISA over a follow up period of 14 days.

RESULTS

After the alcali burn the aqueous prostacyclin level on the right eye is increased from 327 pg/ml aqueous to 27098 pg/ml aqueous, but on the left it stays normally. In conjunctiva and anterior uvea we measured normal amounts of prostacyclin.

CONCLUSIONS

We could not find a consensual increase in prostacyclin formation in the anterior part of the fellow eye following alcali burn.

[Effect of non-steroidal anti-inflammatory drugs on inflammatory reaction. An animal experiment study]

Previous investigations indicate that the application of a cyclooxygenase inhibitor alone can lead to amplification of the inflammatory process. To prevent this response a combination of flurbiprofen and leukotriene receptor antagonist (S 872419 A, Hoechst AG, Frankfurt/Main) were tested in an animal model. The right eye of 48 rabbits was burned with alcali (0.25 mol/l sodium hydroxide). Thirty animals were treated with (0.03% flurbiprofen sodium eye drops and 1% S872419 A eye drops, five times daily). Eighteen animals received no therapy for up to 14 days. Hyperemia of the limbal vessels, corneal vascularization, the number of PMNLs in the cornea and the prostacyclin level in the anterior chamber of the eye (ELISA) served as criteria. On day 3, after the chemical burn only the therapy group showed a significant decrease in hyperemia of the limbal vessels (14th day: score with therapy 0.3, without 2.17, P < 0.05). Without therapy corneal vascularization filled a much larger area from the 6th day on (14th day: area with therapy 3.5 mm2, without 63.7 mm2, P < 0.05). The number of PMNLs was effectively limited by therapy in the superficial stromal layers of the cornea and with therapy showed 2.4 cells/0.014 mm2 and without 18 cells/0.014 mm2 after 48 h. Without Therapy the level of prostacyclin was up to 15 times higher than with (12-h value with therapy) 607 pg/ml, without 9094 pg/ml, P < 0.05). Suppression of cyclo- and lipoxygenase-mediated inflammatory responses is possible with the combination of flurbiprofen and S 872419 A when two arachidonic by inhibition of prostanoid synthesis and leukotriene receptor block at the same time.