Mathematical efficiency calibration in gamma spectroscopy

Mathematical efficiency calibration with the LabSOCS software was introduced for two detectors in the measurement laboratory of the Central Safety Department of Forschungszentrum Karlsruhe. In the present contribution, conventional efficiency calibration of gamma spectroscopy systems and mathematical efficiency calibration with LabSOCS are compared with respect to their performance, uncertainties, expenses, and results. It is reported about the experience gained, and the advantages and disadvantages of both methods of efficiency calibration are listed. The results allow the conclusion to be drawn that mathematical efficiency calibration is a real alternative to conventional efficiency calibration of gamma spectroscopy systems as obtained by measurements of mixed gamma ray standard sources.

Missense mutation within cystic fibrosis transmembrane conductance regulator (CFTR) gene is associated with selected parameters of the frozen-thawed sperm in Holstein-Friesian bulls

In our previous Genome-wise Association Study we found that Cystic Fibrosis Transmembrane Conductance Regulator gene (CFTR) is a candidate gene for sperm motility in fresh semen of Holstein-Friesian bulls. Since in cows thawed semen is commonly used for the artificial insemination (AI) we have decided to find out whether functional polymorphism within CFTR gene coding sequence is associated with selected parameters of thawed sperm, including their motility evaluated by computer-assisted sperm analysis (CASA), the activity of three antioxidant enzymes: glutathione peroxidase (GPx) catalase (CAT), superoxide dismutase (SOD), ATP content and integrity of sperm membranes. One hundred twenty Holstein Friesian bulls kept in uniform environmental conditions (one AI company) were included in the study. Significant associations between genotypes of missense mutation within exon 11 of the CFTR gene (Met468Leu) and the activity of antioxidant enzymes and sperm mitochondrial function were revealed. No effect of CFTR genotypes on sperm motility was observed. Significant differences in CAT and SOD activity were found between AA and TT homozygous individuals. Bulls with TT genotype had the lowest activity of both antioxidant enzymes. The same bulls also showed the lowest number of sperm with active mitochondria. Our results demonstrate that missense mutation Met468Leu within CFTR gene is associated with antioxidant enzyme activity and mitochondrial function of bovine thawed sperm without affecting their motility.

[Precision pulse capsulotomy : The new capsulorhexis?]

The manual capsulorhexis created by Neuhann is still the standard procedure for opening the anterior capsule for cataract surgery. A limitation is the inaccuracy in the size and placement of the opening due to manual execution. In addition to the femtosecond laser a possible improvement in the standardization of capsulorhexis is provided by the Zepto procedure (precision pulse capsulotomy, PPC). In this case a 5.25 mm rhexis is created in a standardized fashion with a flexible suction adapter in which a nitinol ring is located. Whether the strength of PPC is comparable or better than that of the manual technique and how it behaves in terms of capsule shrinkage has not yet been finally clarified.

Massively Parallel Interrogation of the Effects of Gene Expression Levels on Fitness

Data of gene expression levels across individuals, cell types, and disease states is expanding, yet our understanding of how expression levels impact phenotype is limited. Here, we present a massively parallel system for assaying the effect of gene expression levels on fitness in Saccharomyces cerevisiae by systematically altering the expression level of ∼100 genes at ∼100 distinct levels spanning a 500-fold range at high resolution. We show that the relationship between expression levels and growth is gene and environment specific and provides information on the function, stoichiometry, and interactions of genes. Wild-type expression levels in some conditions are not optimal for growth, and genes whose fitness is greatly affected by small changes in expression level tend to exhibit lower cell-to-cell variability in expression. Our study addresses a fundamental gap in understanding the functional significance of gene expression regulation and offers a framework for evaluating the phenotypic effects of expression variation.

Missense mutation in glutathione-S-transferase M1 gene is associated with sperm motility and ATP content in frozen-thawed semen of Holstein-Friesian bulls

Glutathione-S-transferase genes (GSTs) encode enzymes that are involved in detoxification and neutralization of reactive oxygen species (ROS) in male reproductive system and play protective role during spermatogenesis. The aim of the study was to evaluate whether C/G missense mutation (rs135955605) within glutathione-S-transferase M1 (GSTM1) gene is associated with selected parameters of frozen-thawed semen in 309 Holstein-Friesian bulls. Single nucleotide substitution C/G was identified by amplification of GSTM1 gene fragment followed be digestion with restriction enzyme DdeI. Bulls with GG genotype were the most frequent (67.96%), in comparison to CC (2.59%) and GC (29.45%). Significant associations were found between GSTM1 genotypes and ATP content and total sperm motility. Bulls with GG genotype had the highest values for both traits. Rare variant C of GSTM1 was associated with significant decrease of sperm motility and ATP content. Our results demonstrate that C/G missense mutation within GSTM1 gene is involved in bull sperm quality.

Genome-wide association study for semen volume and total number of sperm in Holstein-Friesian bulls

In artificial insemination industry bulls producing high volume of semen with relatively high concentration of sperm are very desirable since they ensure stable production of commercial straws especially in case of top bulls. The aim of the study was to screen the entire bull genome to identify markers and candidate genes underlying semen volume (SV) and total number of sperm (TNS) in ejaculate produced by Holstein-Friesian bulls. Data on semen production were retrieved from records of AI center and included a population of 877 Holstein-Friesian bulls. Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome-wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model for Linear Regression Analysis was used to estimate the effect of SNP marker for SV and TNS. After Bonferroni correction, 3 markers located on chromosome 22 reached the highest significance (rs41625599, rs41584616, rs42012507) for both traits. In the vicinity of these significant markers 3 genes are located (DCP1A, SFMBT1, TMEM110). Moreover, marker rs110109069 located on chromosome 25 was significantly associated with TNS and marker rs42438348 located on chromosome 10 has been found to be associated with SV. Some additional candidate genes were suggested to be potentially involved in analyzed traits (GALC, PRKCD, PHF7, TLR9, SPATA7). Identifying SNPs associated with the lower total number of sperm may be very useful for early recognition of a young sire as less suitable for effective semen production in artificial insemination centers.

Genome-wide association study for sperm concentration in Holstein-Friesian bulls

The aim of the study was to screen the entire bull genome to identify markers and candidate genes underlying sperm concentration. The analysed data set originates from a population of 877 Polish Holstein-Friesian bulls. Based on sperm concentration value, two extreme groups of bulls were created: Low (L, n = 126) and High (H, n = 140). Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome-wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model with a Cohran-Armitage test, Correlation/Trend adjusted by a Bonferroni test, was used to estimate the effect of SNP marker for sperm concentration. Thirteen markers reached genome-wide significance. The most significant SNPs were located on chromosome 3 (rs109154964 and rs108965556), 14 (rs41621145) and 18 (rs41615539), in the close vicinity of protein arginine methyltransferase 6 (PRMT6), Sel1 repeat containing 1 (SELRC1), triple QxxK/R motif containing (TRIQK) and zinc finger homeobox 3 (ZFHX3) genes, respectively. For three other candidate genes located close to significant markers (within a distance of ca 1 Mb), namely histone deacetylase 9 (HDAC9), an inhibitor of DNA binding 2 (ID2) and glutathione S-transferase theta 1 (GSTT1), their potential role in the production of male germ cells was confirmed in earlier studies. Six additional candidate genes (Vav3, GSTM1, CDK5, NOS3, PDP1 and GAL3ST1) were suspected of being significantly associated with sperm concentration or semen biochemistry. Our results indicate the genetic complexity of sperm concentration but also open the possibility for finding causal polymorphism useful in marker-assisted selection.

Genome-wide association study for poor sperm motility in Holstein-Friesian bulls

The aim of the study was to screen the whole bull genome to identify markers and candidate genes underlying poor sperm motility. The analyzed data set originates from the Polish Holstein-Friesian bull population and consists of 41 Case and 279 Control bulls (selected from 1581 bulls). The most distinguishing trait of case group was very poor sperm motility (average 25.61%) when compared to control samples (average 72.95%). Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome-wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model with a Cohran-Armitage test, Correlation/Trend adjusted by Bonferroni test were used to estimate the effect of Single Nucleotide Polymorphism (SNP) marker for poor sperm motility. Markers (n=34) reached genome-wide significance. The most significant SNP were located on chromosome 24 (rs110876480), 5 (rs110827324 and rs29011704), and 1 (rs110596818), in the close vicinity of melanocortin 4 receptor (MC4R), PDZ domain containing ring finger 4 (PDZRN4) and ethanolamine kinase 1 (ETNK1), olfactory receptor 5K3-like (LOC785875) genes, respectively. For five other candidate genes located close to significant markers (in distance of ca. 1 Mb), namely alkaline phosphatase, liver/bone/kidney (ALPL), tripartite motif containing 36 (TRIM36), 3-hydroxyisobutyrate dehygrogenase (HIBADH), kelch-like 1 (KLHL1), protein kinase C, beta (PRKCB), their potential role in sperm motility was confirmed in the earlier studies. Five additional candidate genes, cystic fibrosis transmembrane conductance regulator (CFTR), insulin-like growth factor 1 receptor (IGF1R), steroid-5-alpha-reductase, alpha polypeptide 2 (SRD5A2), cation channel, sperm associated 1 (CATSPER1) calpain 1 (mu/I) large subunit (CAPN1) were suggested to be significantly associated with sperm motility or semen biochemistry. Results of the present study indicate there is a genetic complexity of poor sperm motility but also indicate there might be a causal polymorphism useful in marker-assisted selection. Identifying genomic regions associated with poor sperm motility may be very important for early recognition of a young sire as unsuitable for effective semen production in artificial insemination centers.

[Associations between 60 SNPs identified by APEX microarray and growth rate, meatiness and selection index in boars]

A total of 312 boars (201 Landrace and 111 Large White) were genotyped with a custom-made low throughput genotyping microarray (called SNiPORK) based on array primer extension (APEX) technology. The results were used to association studies between genotyped SNP markers and daily gains, meat content and selection index. Among the 60 SNP markers analyzed, 14 of them showed statistically significant associations between the genotype and the level of at least one trait. In order to find extremely beneficial or unfavorable intergenic diplotype combinations, 5 SNP markers were selected: CASTA499C, MYF6 T255C, PKLR C384T, SFRSI C1146T and TNNT3T 153C, which showed statistically significant associations at P<or=0.01 within one of the traits and the frequency of homozygotes with a minor allele of at least 0.1. Among 10 possible permutations, statistically significant associations were found only for a combination of SNP markers in TNNT3 x SFRSI genes and, interestingly, for all combinations with SNP located within the calpastatin (CAST) gene commonly known as a gene influencing pork quality traits. This study also found that CAST allele A (which is beneficial for pork tenderness) is also favorable for growth rate. This effect is clearly increased with additive alleles C of myogenic factor MYF6 and troponin T3 (TNNT3) and is decreased with each allele Tfrom serine rich splicing factor 1 (SFRS1) gene. For meat content, the most favorable genotype of calpastatin gene was AC, the effect of which was generally increased with each C allele of MYF6 and TNNT3 and decreased with each allele T from SFRSl and PKLR (puruvate kinase) genes, respectively. The calpastatin AC genotype seemed to be beneficial for selection index, although in combination with the CC genotype of troponin T3, calpastatin genotypes AA and CC reached higher values. In the case of the combination of genotypes TNNT3 x SFRS1, the most preferable for all analyzed traits is the CC genotype of TNNT3, especially in combination with CTor CC genotypes in the SFRS1 gene. We conclude that searching for interaction effects between candidate SNPs (even of moderate influence) may lead to interesting and valuable findings enabled better understanding and applications of SNPs in pork yield and quality improvement programmes.

Additive effects of 19 porcine SNPs on growth rate, meat content and selection index

A total of 306 boars (108 Large White and 198 Landrace) were genotyped for 52 candidate SNPs to determine which of the polymorphisms influence growth rate, meat content and selection index. The effects of SNPs were estimated by a mixed linear model including a random additive polygenic animal effect, fixed effects of SNPs including additive, and pairwise additive-by-additive epistases, year*season of birth, breed and RYR1 genotype. In order to estimate all possible pairwise SNP combinations without overparameterising the model a stochastic approach was adopted. A total of 1 350 replications of the model were generated, each containing five randomly selected SNPs. The final estimates of the fixed effects of the model equaled an average out of the replications. The hypothesis of a nonzero effect of SNP was tested by the Wald test. Among 4 257 estimates calculated, many significant (P<0.01), but mostly minor effects (below 1 phenotypic standard deviation) were recorded. The selected SNPs will be further investigated to determine which may be used in MAS.

Deletion/insertion polymorphism of the prion protein gene (PRNP) in Polish red cattle, Polish White-backed cattle and European bison (Bison bonasus L., 1758)

The aim of the present study was to identify deletion/insertion polymorphism of the bovine prion protein (PRNP) gene within the promoter sequence (23 bp indel), intron 1 (12 bp indel) and the 3' end untranslated region (14 bp indel). The experiment was performed on three groups of animals protected under a genetic resources conservation program: 139 Polish Red (PR) cows, 79 Polish White-backed cows and 50 European bison (Bison bonasus L., 1758). White-backed cattle were characterized by a higher frequency of ins/del heterozygotes and a relatively lower frequency of ins/ins homozygotes within the promoter sequence region (23 bp indel), compared to Polish Red cattle. At the polymorphic locus of intron 1 (12 bp indel) the genetic structure of both cattle populations was similar. Monomorphism, expressed by the occurrence of one genotype variant in each of the analyzed sequence regions, was observed in European bison. Five haplotypes were found in Polish White-backed cows, four haplotypes in Polish Red cows and only one in analyzed group of bison. Differences between the observed and expected number of PRNP haplotypes were recorded in Polish Red cattle.

Single nucleotide polymorphism in the promoter region of the lactoferrin gene and its associations with milk performance traits in Polish Holstein-Friesian cows

Bovine lactoferrin (LTF) is a multifunctional small glycoprotein found in milk acting mainly as a defense factor in the mammary gland. Many polymorphisms have been found in the bovine LTF gene but almost none were considered as genetic markers of production traits in dairy cattle. In this study, the promoter fragment of LTF gene containing mutation (G/C) in position +32 has been amplified by PCR followed by genotyping by the SSCP and RFLP method. 358 Polish Holstein-Friesian cows were screened, giving the following frequency of genotypes: 0.628, 0.313 and 0.059 for GG, GC and CC, respectively. GLM (General Linear Model) analysis was applied to evaluate the associations of lactoferrin with milk performance traits, including SCC - somatic cell count. It was found that CC cows show significantly higher (P < or = 0.01) protein content in milk in comparison with GG cows. The values of other milk performance traits were also higher but at non-significant levels. SCC in milk was the lowest in CC cows, but also at a non-significant level.

The Role of ERK5 in T-Cell Signalling

The mitogen-activated protein kinase (MAPK) ERK5 plays an important role in mammary epithelial proliferation, endothelial cell survival and normal embryonic development. In nonhaematopoietic cells, mitogenic and stress signals activate the ERK5 cascade. Here, we investigated the role of the ERK5 pathway in T-cell activation and show that primary and leukaemic T cells express ERK5, whose activating phosphorylation is induced by antibodies against CD3 but not by phorbol myristate acetate treatment. ERK5 localized in the cytosol and nucleus in quiescent and activated T cells. In the latter, ERK5 phosphorylation was mainly observed in the nucleus. Selective activation of the ERK5 cascade by transfecting constitutively active MEK5 and wildtype ERK5 induced a reporter gene driven by the IL-2 promoter while barely affecting CD69 expression. These results suggest a new role for the ERK5 cascade in intracellular signalling in T cells.

Distinct Functions of Vav1 in JNK1 Activation in Jurkat T Cells Versus Non-Haematopoietic Cells

Vav1, the 95-kDa protein encoded by the vav1 proto-oncogene, is expressed exclusively in haematopoietic cells, where it becomes phosphorylated on tyrosine residues in response to antigen receptor ligation. Vav1 was found to act as a Rac1-specific guanine nucleotide exchange factor and to activate c-Jun N-terminal kinase (JNK1) in vitro and in ectopic expression systems using non-haematopoietic cells. Here, we studied the role of Vav1 in JNK1 activation in T cells versus non-haematopoietic cells. Vav1 overexpression activated JNK1 in COS7 and 293T cells but not in Jurkat T lymphocytes. In contrast, constitutively activated Rac1 efficiently stimulated JNK1 in both cell types under the same conditions. Vav1 did function in T cells because it clearly stimulated the activity of a nuclear factor of activated T-cell reporter plasmid in the same cells. Moreover, Vav1 induction of JNK1 in T cells required coexpression with calcineurin. This cooperation was cell type specific because it was not observed in COS7 or 293T cells. In contrast, Vav1 did not cooperate with calcineurin to activate either extracellular signal-regulated kinase 2 or p38. These findings demonstrate that Vav1 alone is a poor activator of the JNK1 pathway in T cells and emphasize the importance of studying the physiological functions of Vav1 in haematopoietic cells.

Comparative study of 137Cs partitioning between solid and liquid phases in Lakes Constance, Lugano and Vorsee

The methodology for estimating radiocaesium distribution between solid and liquid phases in lakes is applied for three prealpine lakes: Lake Constance (Germany), Lake Lugano (Switzerland) and Lake Vorsee (Germany). It is based on use of the exchangeable distribution coefficient and application of the exchangeable radiocaesium interception potential (RIPex). The methodology was tested against experimental data. Good agreement was found between estimated and measured 137Cs concentrations in Lake Constance and Lake Lugano, whereas for Lake Vorsee a discrepancy was found. Bottom sediments in Lake Vorsee are composed mainly of organic material and probably cannot be described in terms of the specific sorption characteristics attributed to illitic clay minerals.

Safety and pharmacokinetics of multiple 750-milligram doses of intravenous levofloxacin in healthy volunteers

The safety and pharmacokinetics of a once-daily high intravenous dose of levofloxacin (750 mg) in 18 healthy volunteers were studied in a double-blind, randomized, placebo-controlled, single-center parallel group study. Levofloxacin was well tolerated, and higher maximum concentration of drug in serum and area under the concentration-time curve values were achieved. For difficult-to-treat infections, high daily doses of levofloxacin may be beneficial, and intravenous administration may be preferred in certain clinical settings, such as when treating patients in intensive care units, warranting further evaluation.

Time-dependence of the radiocaesium contamination of roe deer: measurement and modelling

In spruce forest and peat bog, the migration of 137Cs from soil to plants, fungi, roe deer and consumers has been surveyed. In spruce forest the 137Cs activity concentration in roe deer decreases slowly with time and has superimposed periodic maxima in autumn which are correlated with the mushroom season. The decrease with time can be described by an effective half-life of 3.5 yr caused by a fraction of the 137Cs in the soil becoming unavailable for green grazing plants with time. The additional transfer of 137Cs into roe deer meat during the mushroom season depends on precipitation in July, August and September which also determines the yield of fungi in autumn. Our model confirms the assumption that fungi also have access to a fraction of the 137Cs in the soil which is unavailable for green plants. On peat bog the 137Cs activity concentration in roe deer is higher than in spruce forest and its effective half-life is about 17 yr, due to reversible binding of 137Cs to organic matter in the peat bog.

Immunohistochemical detection of estrogen and progesterone receptor in human cornea

OBJECTIVE

For treatment of postmenopausal keratoconjunctivitis sicca hormone therapy is favored by some clinicians. The likely morphological basis assessing the hormone receptor status in the human cornea has not been performed. Immunohistochemical staining methods provide the opportunity to evaluate the hormone receptor content within the histologic compartments of the cornea. The aim of our study was to assess and localize immunohistochemical hormone receptor staining in the human cornea.

METHODS

Formalin-fixed and paraffin-embedded specimens of three pre- and three postmenopausal women were assessed for localization of estrogen receptor (ER) and progesterone receptor (PR) expression with established immunohistochemical hormone receptor staining methods.

RESULTS

No nuclear staining reaction was found in the epi- and endothelial layers of the corneas. The stroma of the corneas showed no immunohistochemical staining reaction in all cases. We found cytoplasmatic PR staining of the endothelial layer in two cases.

CONCLUSIONS

We found no morphological basis in the human cornea for the use of topical steroid hormone treatment in postmenopausal keratoconjunctivitis sicca. Hormone receptor expression in the conjunctiva or in the lacrimal gland may have an impact in some patients showing relief of symptoms in postmenopausal dry eye syndrome.

Corneal Lathing Using the Excimer Laser and a Computer-controlled Positioning System

PURPOSE

To present the excimer laser corneal shaping system (ELCS-S), an add-on device to the Keratom, a commercially available 193-nm excimer laser built by Schwind.

METHODS

The system is designed for the preparation of donor corneas under sterile conditions using the ultraviolet laser to offer greatest possible flexibility. Lenticules for planolamellar grafting and refractive epikeratoplasty, as well as donor buttons for penetrating keratoplasty can be computer-designed by the surgeon or technician and lathed with the system.

RESULTS

Using the excimer laser corneal shaping system (ELCS-S) on human donor corneas, the central surface of the epikeratoplasty lenticule exhibited only narrow, flat concentric notches corresponding to the single lathing steps. Transmission electron microscopy revealed a damage zone of less than 0.3 microm in close approximation to the treated surface. The final thickness revealed a difference of less than +/-53 microm from the intended, initially programmed value. Ultrastructural studies showed the perpendicular stromal surface of the penetrating keratoplasty buttons to be smooth with minimal protrusion of Descemet's membrane. Endothelial injury was observed in a zone averaging between 40 and 100 microm adjacent to the cutting edge only.

CONCLUSION

The excimer laser corneal shaping system (ELCS-S) allows a computer-controlled, surgeon-designed, sterile preparation of lamellar and penetrating corneal grafts with the use of the excimer laser. This could offer significant advantages in comparison to presently available systems for lamellar dissection and trephination.

A new sponge profile for retinal detachment surgery: design and in vitro-effectiveness

PURPOSE

To develop a new, calculated design for episcleral sponges to achieve sufficient indentation under avoidance of form related side effects.

DESIGN AND METHODS

The new sponge profile consists of two convex halves with different radii, with a calculated optimum relation between inner and outer radius. It was tested on pig eyes and compared with round and half cut sponges. The height of the intraocular buckle was determined by ultrasound (A-Scan, Biovision V Plus), the extraocular height using ultrasound biomicroscopy (Humphrey Biomicroscope System Model 840).

RESULTS

The buckle height achieved with the new design showed no significant difference to round sponges, whereas the extrascleral height was significantly lower compared to round sponges (p<0.001). Half cut sponges showed significantly less buckle height compared to round sponges (p<0.001) and to the new design (p<0.02).

CONCLUSION

The new design produces sufficient indentation combined with minor change of the outer globe contour. It has the potential to be as efficient as conventional round sponges, but more tolerable for the patient by reduction of form related side effects.

Laser shaping of corneal transplants in vitro: area ablation with small overlapping laser spots produced by a pulsed scanning laser beam using an optimizing ablation algorithm

Area laser lathing and trephination of donor corneas is used to produce different types of grafts for human transplantation. 193 nm (ArF excimer) laser radiation is used, since this is known to give a non-thermal laser-tissue interaction with a minimal zone of tissue damage. To guarantee the highest degree of flexibility concerning the overall shape of the grafts as well as their thickness profiles, we use a small (compared with the area to be ablated) scanning laser spot. For area lathing of the tissue we have developed a new ablation algorithm (optimized scanning laser ablation, OSLA) that can be applied to lathe and perforate any tissue--with concave (as in this application), convex or plane surface geometry--where surface precision and smoothness are key issues. Using OSLA with the Excimer Laser Corneal Shaping System (a tool for in vitro fabrication of all kinds of corneal transplants like donor buttons for keratoplasty, lamellar grafts for epikeratoplasty and refractive lenticules) enabled us to produce all types of corneal grafts with very high precision. This is considered to be a major improvement towards the production of refractive lenticules.

Regulating the activity of a cardioacceleratory peptide

We measured the effect of crustacean cardioactive peptide on Drosophila heart rate in the animal and in a tissue preparation. Crustacean cardioactive peptide increased in vivo basal heart rate 1%, 6%, and 19% and increased in vitro basal heart rate 52%, 25%, and 35% in larvae, pupae, and adults, respectively. In the tissue preparation, the acceleratory period was followed by decreased in vitro heart rates of 42%, 16%, and 13% in larvae, pupae, and adults, respectively. The effects observed in the animal and tissue and in larvae, pupae, and adults suggest that Drosophila crustacean cardioactive peptide cardiac signaling is modulated and developmentally regulated.

Influence of dorzolamide on corneal thickness, endothelial cell count and corneal sensibility

PURPOSE

Dorzolamide (Trusopt) is the first topical carbonic anhydrase inhibitor (CAI) that is in clinical use in glaucoma therapy. It is known that CAI have a negative effect on corneal endothelial pumpfunction and therefore on the whole corneal physiology.

METHODS

20 patients with open angle glaucoma or ocular hypertension and an elevated intraocular pressure (IOP) over 21 mmHg and without prior oral CAI-treatment were included in this study. Trusopt was administered t.i.d. as monotherapy and b.i.d. in combination with other topical antiglaucoma drugs. Corneal ultrasound pachymetry, corneal endothelial cell count and aesthesiometry were performed prestudy and on days 1, 8, 15, 30, 60 and 90.

RESULTS AND CONCLUSIONS

Mean corneal thickness was slightly increased on day one (statistically non-significant) and returned to baseline measurements at the following visits, no changes in endothelial cell count and corneal anesthesia were found. Topical dorzolamide is not associated with clinically meaningful changes of the cornea.

[Refractive laser surgery of the cornea]

The importance of refractive corneal laser surgery is increasing. Since the introduction of the Excimer laser in 1990 approximately 350.000 eyes were treated worldwide until the end of 1996. Postoperative refraction is mainly determined by the amount of intended correction: correction of myopia of up to -6 dpt using photorefractive keratectomy (PRK) has a success rate surpassing 93%, in higher myopic corrections the success rate drops to 30%. The complication rate is also directly related to the amount of correction: with corrections of up to 6 dpt it reaches up to 3% and in corrections of over 9 dpt manifest scars occur in more than 10%. Better results in myopias over -7 dpt are achieved using the laser in situ keratomileusis (LASIK), which is a combination of lamellar corneal surgery and the excimer laser. With LASIK the complication rate in corrections of up to 6 dpt is higher compared to PRK. The correction of hyperopia has still a fairly low success rate with both techniques that we suppose hyperopia to be a relative contraindication for corneal laser surgery.

Impact of growth factors on morphometric corneal endothelial cell parameters and cell density in culture-preserved human corneas

PURPOSE

Donor corneas can be preserved for < or = 4 weeks in organ culture (31 degrees C) by using modified minimal essential medium (MEM). About one fifth of them have to be discarded, however, as disintegration of the endothelial cell monolayer-enhanced polymegethism, cell loss-occurs. The objective of this study was to investigate whether addition of insulin, dextran, and epidermal growth factor (EGF) makes corneal endothelial cells more viable, stable, and homogeneous.

METHODS

Sixteen paired human donor corneas were cocultured in media supplemented with EGF and insulin-like growth factor (IGF) or in conventional modified MEM for 4 weeks. Endothelial parameters were evaluated at the outset and at days 7, 14, 21, and 28 of culture by using an automated digital image-analysis system.

RESULTS

No significant differences were observed in the first 2 weeks of culture. Beginning with day 14, however, stabilization of endothelial cell patterns was evident for corneas cultured in supplemented culture media.

CONCLUSION

Our data indicate that the addition of growth factors to culture media might increase the percentage of corneas available for transplantation and would also allow a significantly longer period of preservation.

The mydriatic effect of tropicamide and its diagnostic use in Alzheimer's disease

The mydriatic effect of topically administered tropicamide was investigated as a possible diagnostic indicator for Alzheimer's disease. Although an initial series seemed to show a correlation between hypersensitivity to tropicamide and intellectual impairment, subsequent testing showed a greater inter- and intra-individual variation than that between the normal group and the group of patients with intellectual impairment. This procedure seems, therefore, to lack sufficient specificity to be useful for such a diagnostic purpose.

Ultrasound biomicroscopy of tangential keratotomy incision depth after penetrating keratoplasty

PURPOSE

To assess the accuracy and reproducibility of using ultrasound biomicroscopy to measure corneal refractive incisions in vivo.

SETTINGS

Department of Ophthalmology, University of Vienna, Austria.

METHODS

Ultrasound biomicroscopy was performed in five eyes of five patients who had previous tangential keratotomy for high postkeratoplasty astigmatism. Depth of the incision scar was documented, and the measurements were compared with those obtained preoperatively by ultrasound pachymetry readings of the corneal thickness and with the settings of the diamond knife blade.

RESULTS

The measured depths reached 84.7% +/- 12.9 (SD) of corneal thickness compared with the intended 89.1 +/- 6.7% depth of incision. The relation between knife setting and achieved depth was 95.3 +/- 15.9%.

CONCLUSION

Ultrasound biomicroscopy provided high-quality images of the incision scars, accurately measuring actual incision depth in vivo. It may become a clinically useful tool for the refractive surgeon as it contributes to the predictability and accuracy of keratorefractive procedures.