[Central corneal thickness measurement with online optical coherence pachymetry and ultrasound pachymetry in 513 consecutive eyes]

BACKGROUND

The aim of this study was to assess the reliability of online optical coherence pachymetry (OCP) integrated into the Technolas excimer platform by comparing the intraoperative OCP corneal thickness measurement with the preoperative standard ultrasound pachymetry (USP).

PATIENTS/MATERIALS AND METHODS

The mean central corneal thickness of 513 consecutive eyes was measured using OCP and USP. Immediately before starting the LASIK procedure, three OCP measurements of the central cornea (OCPonline, Heidelberg Engineering GmbH, Germany) were done under the microscope of the Excimer laser (Technolas, Bausch and Lomb, Rochester, NY). The mean value of 10 central USP measurements (Sp-3000, Tomey, Japan) was obtained during the preoperative assessment of the patients. The comparison of the two methods was done using Pearson regression analysis and the Bland- Altman method.

RESULTS

Mean central corneal thickness of the OCP and the USP were 523.1 +/- 30.5 microm and 561.2 +/- 32.7 microm, respectively. The correlation coefficient was r = 0.891 for the two methods. The mean difference between USP and OCP was 37.9 +/- 14.8 microm.

CONCLUSIONS

The intraoperative OCP gives 7% smaller measurements compared with the preoperative USP.

[Early visual recovery after cataract surgery using topical and intracameral anesthesia]

INTRODUCTION

Topical anaesthesia in cataract surgery permits early visual rehabilitation due to the reduced impact on the optic nerve function. In this prospective study, we evaluated the course of visual improvement after surgery.

PATIENTS AND METHODS

45 consecutive patients with senile cataract and no concomitant eye disease were included in the study. Cataract surgery by clear corneal phacoemulsifaction was performed with insertion of a foldable IOL in the capsular bag under topical anaesthesia. For anaesthesia topical lidocaine gel (2 %) and intracameral injection of 0.15 ml lidocaine (1 %) was used. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were measured in decimal fractions within 4 hours after surgery and 1 day postoperatively.

RESULTS

The average preoperative UCVA was 0.23 +/- 0.39 and BCVA was 0.38 +/- 0.23 SD. Four hours postoperatively UCVA and BCVA improved significantly to 0.48 +/- 0.24 and 0.68 +/- 0.18, respectively. One day after surgery, the average UCVA was 0.65 +/- 0.15 and the BCVA was 0.89 +/- 0.07. 75 % (34) of the patients improved to a UCVA of 0.5 or better. The visual acuity improved in all patients one day after surgery, with 60 % (27) of the patients achieving a BCVA of 0.9 or better one day postoperatively. The postoperative corneal function had a significant influence on visual recovery (p = 0.01).

CONCLUSION

A significant visual improvement was observed immediately after cataract surgery using the combination of topical and intracameral anaesthesia. 75 % of the patients reached a UCVA, which permitted sufficient visual function for mobility and orientation. Thus, the rapid recovery of visual function suggests an increased safety, particularly for out-patient surgery.

Regulation of vesicular monoamine and glutamate transporters by vesicle-associated trimeric G proteins: new jobs for long-known signal transduction molecules

Neurotransmitters of neurons and neuroendocrine cells are concentrated first in the cytosol and then in either small synaptic vesicles ofpresynaptic terminals or in secretory vesicles by the activity of specific transporters of the plasma and the vesicular membrane, respectively. In the central nervous system the postsynaptic response depends--amongst other parameters-on the amount of neurotransmitter stored in a given vesicle. Neurotransmitter packets (quanta) vary over a wide range which may be also due to a regulation of vesicular neurotransmitter filling. Vesicular filling is regulated by the availability of transmitter molecules in the cytoplasm, the amount of transporter molecules and an electrochemical proton-mediated gradient over the vesicular membrane. In addition, it is modulated by vesicle-associated heterotrimeric G proteins, Galphao2 and Galphaq. Galphao2 and Galphaq regulate vesicular monoamine transporter (VMAT) activities in brain and platelets, respectively. Galphao2 also regulates vesicular glutamate transporter (VGLUT) activity by changing its chloride dependence. It appears that the vesicular content activates the G protein, suggesting a signal transduction from the luminal site which might be mediated by a vesicular G protein-coupled receptor or as an alternative possibility by the transporter itself. Thus, G proteins control transmitter storage and thereby probablylink the regulation of the vesicular content to intracellular signal cascades.

Serotonin uptake and release mechanisms in developing cultures of rat embryonic raphe neurons: age- and region-specific differences

The development of serotonergic neurons of the rat raphe was followed in primary neuronal cell cultures taken at embryonic days embryonic day 13 and embryonic day 14 from three different raphe sub-groups, topographically defined with respect to their position to the isthmus as rostral (R1), intermediate (R2) and caudal (R3). In neurons cultivated from embryonic day 13 raphe serotonin, immunoreactivity was detected after only two days in vitro in the rostral R1 and the intermediate R2 sub-groups. Within two weeks of cultivation the number of serotonergic neurons as well as the dendritic branching continuously increased in all three sub-groups. In cultures obtained from embryonic day 13 raphe a specific uptake of [3H]serotonin could not be detected during the first days in vitro. Specific uptake as well as regulated serotonin release, however, was clearly discernible in these cultures after nine days in vitro, indicating developmental differentiation of the initially immature serotonergic neurons in culture. In contrast, serotonergic neurons obtained from the three raphe sub-groups at embryonic day 14 took up and released [3H]serotonin, as early as after two days in culture. Basal as well as stimulated serotonin release was diminished when preincubating the cells with tetanus toxin, which cleaves synaptobrevin thereby blocking exocytosis. Our data indicate that the differential development of serotonergic neurons in the various raphe sub-groups in vivo is also sustained in culture. The differences observed when comparing neurons from embryonic days 13 and 14 suggest that a short time-period of about 24h appears to be crucial for the developmental upregulation of serotonin uptake, storage and release.

The neuronal monoamine transporter VMAT2 is regulated by the trimeric GTPase Go(2)

Monoamines such as noradrenaline and serotonin are stored in secretory vesicles and released by exocytosis. Two related monoamine transporters, VMAT1 and VMAT2, mediate vesicular transmitter uptake. Previously we have reported that in the rat pheochromocytoma cell line PC 12 VMAT1, localized to peptide-containing secretory granules, is controlled by the heterotrimeric G-protein Go(2). We now show that in BON cells, a human serotonergic neuroendocrine cell line derived from a pancreatic tumor expressing both transporters on large, dense-core vesicles, VMAT2 is even more sensitive to G-protein regulation than VMAT1. The activity of both transporters is only downregulated by Galphao(2), whereas comparable concentrations of Galphao(1) are without effect. In serotonergic raphe neurons in primary culture VMAT2 is also downregulated by pertussis toxin-sensitive Go(2). By electron microscopic analysis from prefrontal cortex we show that VMAT2 and Galphao(2) associate preferentially to locally recycling small synaptic vesicles in serotonergic terminals. In addition, Go(2)-dependent modulation of VMAT2 also works when using a crude synaptic vesicle preparation from this brain area. We conclude that regulation of monoamine uptake by the heterotrimeric G proteins is a general feature of monoaminergic neurons that controls the content of both large, dense-core and small synaptic vesicles.