Development of surgical techniques for implantation of a wireless intraocular epiretinal retina implant in Göttingen minipigs

Background

The aim of this study was to develop surgical methods for the implantation of a wireless intraocular epiretinal retina implant (EPI RET3) in Göttingen minipigs. This animal model resembles closely the anatomical conditions in humans, and is thus suitable for investigating the EPI RET3 implant as designed for the application in humans.

Methods

Phacoemulsification and vitrectomy was performed on the right eye of 16 Göttingen minipigs under general anesthesia. The implants, consisting of a receiver module and an electrode array connected via a flexible micro cable, were inserted through a corneoscleral incision. The receiver module was placed into the sulcus ciliaris and the electrode array was fixed onto the retina temporal to the optic disc with a retinal tack. Minipigs were monitored for intra- and postoperative ocular complications. Follow-up times were 3 (seven minipigs) and 12 weeks (nine minipigs).

Results

Implantation was successfully performed in all 16 minipigs. The complete implantation surgery required on average 2 hours. Intraoperative findings were a minor hemorrhage of the anterior chamber angle in two eyes, one minor iris hemorrhage, and one minor punctiform retinal hemorrhage, which were all reversible. Postoperatively, the corneoscleral incision showed good wound healing in all eyes. Intraocular reactions included mainly fibrin exudation (six eyes) and formation of iris synechiae with the receiver module of the implants (three eyes).

Conclusions

The performed implantation procedures of the intraocular EPI RET3 implant are feasible and reproducible within an acceptable surgical time. The development of inflammatory responses is a specific predisposition of the minipig following any intraocular intervention; nevertheless, the surgical techniques should be further improved to minimize procedure-related reactions. Our results provide a step towards the application of the EPI RET3 system in clinical studies.

     

Two-photon fluorescence lifetime imaging monitors metabolic changes during wound healing of corneal epithelial cells in vitro

Background

Early and correct diagnosis of delayed or absent corneal epithelial wound healing is a key factor in the prevention of infection and consecutive destruction of the corneal stroma with impending irreversible visual loss. Two-photon microscopy (TPM) is a novel technology that has potential to depict epithelial cells and to evaluate cellular function by measuring autofluorescence properties such as fluorescence intensity and fluorescence lifetimes of metabolic co-factors such as NAD(P)H.

Methods

Using non-invasive TPM in a tissue-culture scratch model and an organ-culture erosion model, fluorescence intensity and fluorescence lifetimes of NAD(P)H were measured before and during closure of the epithelial wounds. Influence of temperature and selective inhibition of metabolism on intensity and lifetimes were tested additionally.

Results

Decrease of temperature resulted in significant increase of fluorescence lifetimes and decrease of the relative amount of free NAD(P)H due to decreased global metabolism. Increase in temperature and upregulation of glycolysis through blocking the mitochondrial electron transport chain by rotenone resulted in increased intensity, decreased lifetimes and increase in the relative amount of free NAD(P)H. Changes of lifetimes and free:protein-bound NAD(P)H ratios were similar to changes measured during wound healing in both scratch and erosion models.

Conclusions

Fluorescence lifetime measurements (FLIM) detected enhancement of cellular metabolism following epithelial damage in both models. The prospective detection of cellular autofluorescence in vivo, in particular FLIM of metabolic cofactor NAD(P)H, has the potential to become an indispensible tool in clinical use to differentiate healing from non-healing epithelial cells and to evaluate effects of newly developed substances on cellular metabolism in preclinical and clinical trials.     

A population-based longitudinal study on work environmental factors and the risk of major depressive disorder

To investigate the relation between work environmental factors and the risk of major depressive disorder (MDD) over 1 year, the authors conducted a population-based longitudinal study of randomly selected employees in Alberta, Canada (January 2008 to November 2011). Participants without a current or lifetime diagnosis of MDD at baseline (n = 2,752) were followed for 1 year. MDD was assessed using the World Health Organization's Composite International Diagnostic Interview-Auto 2.1. The overall 1-year incidence of MDD was 3.6% (95% confidence interval: 2.8, 4.6); it was 2.9% (95% confidence interval: 1.9, 4.2) in men and 4.5% (95% confidence interval: 3.3, 6.2) in women. The relations between work environmental factors and MDD differed by sex. In men, high job strain increased the risk of MDD in those who worked 35-40 hours per week; job insecurity and family-to-work conflict were predictive of MDD. Women who worked 35-40 hours per week and reported job insecurity, a high effort-reward imbalance, and work-to-family conflict were at a higher risk of developing MDD. Job strain, effort-reward imbalance, job insecurity, and work-to-family conflicts are important risk factors for the onset of MDD and should be targets of primary prevention. However, these work environmental factors appear to operate differently in men and in women.     

Successive transformation of chronic myelomonocytic leukaemia into acute myeloblastic then lymphoblastic leukaemia, both with minor-bcr rearrangement

We report a case of chronic myelomonocytic leukaemia (CMML), which transformed first into acute myeloblastic leukaemia (AML) and then into acute lymphoblastic leukaemia (ALL). In the AML and ALL phases, chromosome analysis showed a classic Philadelphia chromosome (Ph) t(9;22)(q34;q11). Molecular studies showed breakpoint cluster region rearrangement between exons e1 and a2 compatible with a p190^bcr/abl breakpoint as observed in Ph-positive lymphoblastic acute leukaemia. The minor (m-bcr) rearrangement was also detected during complete remission.
This observation supports a multistep pathogenesis of leukaemias, and that the p190^bcr/abl breakpoint may influence the course of the disease.     

Gene microarray analysis of peripheral blood cells in pulmonary arterial hypertension

The importance of genetic predisposition, inflammation, and autoimmune mechanisms in the development of pulmonary arterial hypertension (PAH) is becoming increasingly clear. We hypothesized that the analysis of gene expression profiles from peripheral blood mononuclear cells would distinguish patients with PAH from normal volunteers. We also hypothesized that a subset of genes would discriminate between patients with idiopathic PAH and pulmonary hypertension related to secondary causes. Mononuclear cells were isolated from 15 patients diagnosed with PAH and 6 normal control subjects. Microarray expression was performed, and the expression profiles were analyzed for consistent and predictive differences in gene expression. We identified a signature set of 106 genes that discriminated with high certainty (p < or = 0.002) between patients with PAH and normal individuals. The results of the microarray analysis were retrospectively and prospectively confirmed by quantitative polymerase chain reaction for 2 of the 106 genes. Supervised clustering analysis generated a list of differentially expressed genes between patients with idiopathic and secondary causes of pulmonary hypertension. Microarray expression profiling of peripheral blood cells can discriminate between patients with PAH and normal volunteers. These findings may have important implications toward diagnosis, screening, and pathogenesis of this disease.     

A heteroplasmic point mutation of mitochondrial tRNALeu(CUN) in non-lymphoid haemopoietic cell lineages from a patient with acquired idiopathic sideroblastic anaemia

Acquired idiopathic sideroblastic anaemia (AISA) has been proposed to be a disorder of mitochondrial DNA (mtDNA). The hallmark of mitochondrial iron overload may be attributable to a respiratory chain defect leading to impaired reduction of ferric iron (Fe^3 +) to ferrous iron (Fe^2 +), which is essential to the last step of mitochondrial haem biosynthesis. In a 71-year-old patient we identified a point mutation in one of the two mitochondrial transfer-RNAs coding for leucine (tRNA^leu(CUN)). The mutation involves a G → A transition in the anticodon loop, immediately adjacent to the anticodon triplet (mtDNA position 12301). The mutated guanine is highly conserved in a wide range of species. The mutation is heteroplasmic, i.e. there is a mixture of normal and mutated mitochondrial genomes (ratio c. 50:50). Heteroplasmy of mtDNA is not found in normal individuals, but is a typical feature of mitochondrial cytopathies. The point mutation was present in the patient's bone marrow and whole blood samples, in purified platelets, and in the granulocyte/erythrocyte pellet after mononuclear cell separation by density gradient centrifugation. The mutation was not found in T- and B-lymphocytes isolated by immunomagnetic bead separation. It was also absent from buccal mucosa cells and cultured skin fibroblasts. This pattern of involvement suggests that the mutation occurred in a self-renewing myeloid stem cell of the CFU-GEMM type.     

Pacemaker-related myocardial perfusion defects worsen during higher pacing rate and coronary flow augmentation.

BACKGROUND: Asynchronous activation resulting from right ventricular apical (RVA) pacing can adversely affect left ventricular function and myocardial perfusion despite normal coronary arteries. This situation makes detection of coronary heart disease in paced patients difficult. OBJECTIVES: The purpose of this study was to assess the distribution, extent, and severity of myocardial perfusion defects with RVA pacing at low and high rates and increased coronary blood flow with adenosine. METHODS: Fourteen patients with permanent RVA pacing and angiographically normal coronary arteries underwent myocardial perfusion single-photon emission computed tomography at rest at low and high pacing rates and with pacing at low rates with adenosine. Data were analyzed semi-quantitatively using a 20-segment scoring model and coded using a four-point scoring system. RESULTS: At rest, 23 (55%) of 42 coronary flow territories showed abnormal perfusion and 52 (19%) of 280 corresponding segments demonstrated abnormal perfusion; mean perfusion score was 0.22. After high-rate pacing, perfusion was abnormal in 31 (74%) of 42 flow territories and 122 (44%) of 280 segments; mean perfusion score was 0.67. Adenosine infusion resulted in 28 (67%) of 42 abnormal flow territories and 90 (32%) of 280 abnormal segments; mean perfusion score was 0.44. Perfusion defects were observed most often in close proximity to the origin of the pacing site. CONCLUSION: RVA pacing results in myocardial perfusion defects. The false-positive findings are present at rest and more obvious with high-rate pacing than during adenosine infusion. Detection of coronary artery disease should be performed with caution in RVA paced patients because of the high number of perfusion defects observed in the absence of coronary artery disease.     

16, 16-Dimethyl PGE2 fails to prevent ethanol-induced drop of gastric potential difference in man

Digestive Diseases and Sciences -