The effect of phytoplankton properties on the ingestion of marine snow by Calanus pacificus.

Marine snow, formed through the aggregation of phytoplankton and other organic matter, can be consumed by various types of zooplankton, affecting both planktonic trophic dynamics and the export of carbon to depth. This study focuses on how two factors-phytoplankton growth phase and species-affect copepod feeding on marine snow. To do this, we conducted a series of grazing experiments using gut pigment and stable isotope methods to quantify the ingestion of the copepod, Calanus pacificus, on both marine snow aggregates and individual phytoplankton. Results demonstrate that marine snow can represent a substantial food source for copepods, comparable to rates on individual phytoplankton. Moreover, we found that both the overall ingestion and the relative ingestion of aggregates vs. individual phytoplankton depended on phytoplankton growth phase for experiments conducted with the diatom Thalassiosira weissflogii. Although copepods consumed aggregates composed of Skeletonema marinoi at similar rates as those composed of T. weissflogii, no effect of growth phase was observed for S. marinoi. These findings suggest that marine snow can be an important source of nutrition for copepods, but that its role in planktonic food webs may differ depending on the phytoplankton community composition and the stage of phytoplankton blooms.

Validation of a new static perimetric thresholding strategy (GATE).

AIMS: To validate the EyeSuite version of German Adaptive Threshold Estimation (GATE), a new thresholding algorithm for automated static perimetry. METHODS: Specification of agreement and its clinical evaluation as validation criteria. Comparison of local differential luminance sensitivity (DLS) and test time values between the prototype version of GATE (GATEp) and a clinical trial version, implemented in EyeSuite (GATEe), by means of modified Bland-Altman plots. All examinations were performed on the Octopus 900 perimeter (Haag-Streit Inc., Köniz, Switzerland). Visually impaired patients (anterior ischaemic optic neuropathy [n=3], glaucomatous optic neuropathy [n=15], (post-)chiasmal visual pathway lesion [n=6], retinitis pigmentosa [n=6]) were either tested with grid 30A (30° excentricity, 83 test locations) or grid 84NO (90° excentricity, 109 test locations, patients with RP only). RESULTS: The comparison of local DLS values showed good-to-acceptable agreement between GATEp and GATEe (bias <2 dB, limits of agreement [LOA] <5 dB) and very good repeatability for GATEp (bias <0.5 dB, LOA<3 dB). Median test times for GATEp and GATEe were 7.8  and 8.8 min for the 30° grid and 6.7  and 7.8 min for the 90° grid. CONCLUSIONS: GATEp and GATE, implemented in the commercially available EyeSuite software package (GATEe), show good agreement regarding local differential luminance sensitivity. GATEe can thus be also recommended for clinical practice. CLINICAL TRIAL NUMBER: NCT01265628.

Assessment of functional and morphometric endpoints in patients with non-arteritic anterior ischemic optic neuropathy (NAION).

BACKGROUND: The primary objective of this bi-center explorative pilot study was the quantitative assessment of visual field defects and retinal nerve fiber layer thickness (RNFT) over 6 months in patients with acute non-arteritic anterior ischemic optic neuropathy (NAION), in order to elucidate the natural course of NAION and provide a reference dataset for future treatment studies. METHODS: 16 patients (age 41-80 years, nine males, seven females) suffering from acute NAION and presenting within 7 days after onset of symptoms were included in this study. The following examinations were carried out at the initial visit (month 0) and at months 2, 4 and 6: entire (90°) visual field examination with automated static white-on-white perimetry, quantified by mean defect (MD); peripapillary retinal nerve fiber layer thickness (RNFT) measurement with spectral domain optical coherence tomography (SD-OCT); assessment of distant best correct visual acuity (D-BCVA) and a quantification of the relative afferent pupillary defect (RAPD) using the swinging flashlight test with neutral density filters. Perimetric Mean Defect (MD) and RNFT values were each compared between the consecutive visits using the non-parametric Friedman test. RESULTS: The initial MD was 6.2 dB (IQR 5.0-7.4) without significant changes further on. RNFT was 183 µm (IQR 148-252) initially, decreased significantly at month 2 (78 µm (IQR 71-93) and further at month 4 (64 µm (IQR 58-74) and 6 (61 µm (IQR 52-81), Friedman test, p < 0.001). Initially, RNFT was above normal limits (due to swelling) in 15/16 patients; at month 2 it was below normal limits in 13/16 patients, at month 4 in 12/13 patients and at month 6 in 9/10 patients. 7/16 patients exhibited segmental swelling of the optic disc, whereas the entire circumference of the optic disc showed RNFL thickening in 9/16 patients. CONCLUSION: Functional deficits were present directly after onset of NAION and did not change relevantly further on. Morphological changes comprise severe swelling after onset of NAION, which rapidly turns into atrophy. Already after 2 months more than 80 % of the patients showed a RNFT below normal limits. Progressive RNFL thinning between month 2 and month 4 suggests ongoing atrophy, whereas a stable morphologic end point is reached after month 4.

Analytical performance of the Investigational Use Only Cervista HPV HR test as determined by a multi-center study.

BACKGROUND: Any HPV test designed to be utilized in cervical cancer screening programs should be highly validated both analytically and clinically. OBJECTIVES: The Investigational Use Only (IUO) Cervista HPV HR test is designed to detect 14 high-risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68). The analytical performance of the Cervista HPV HR test was characterized in a multi-center study. RESULTS: Analytical sensitivity for the 14 high-risk HPV types that the test is designed to detect ranged from 1,250 copies to 7,500 copies per reaction depending on HPV type. Accuracy compared to PCR with bi-directional sequencing was 91.4% [95% CI: 86.5 95.0%]. The reproducibility, when tested at three different testing centers, resulted in an overall inter-run reproducibility (between day/within site) agreement of 98.8% [1-sided 95% Confidence Lower Limit = 96.9%] and an overall inter-site reproducibility (between site) agreement of 98.7% [1-sided 95% Confidence Lower Limit = 97.9%]. The Cervista HPV HR test showed no cross-reactivity with DNA from seven non-oncogenic HPV types or 17 different infectious agents at up to 10(7) copies per reaction. CONCLUSIONS: The analytical performance of the Cervista HPV HR test demonstrates sufficient analytical performance for use in cervical cancer screening. As with any clinical laboratory test, analytical characteristics must be evaluated in light of the clinical performance of this assay.

Invader assay for single-nucleotide polymorphism genotyping and gene copy number evaluation.

The Invader assay (Third Wave Technologies) is a homogeneous, isothermal DNA probe-based method for sensitive detection of nucleic acid sequences. Invader reactions are performed directly on genomic DNA or total RNA targets; however, polymerase chain reaction- or reverse transcriptase polymerase chain re action-amplified products can also be used. Detection is achieved through target-specific signal amplification instead of target amplification. The assay is a highly accurate and specific detection method for both qualitative and quantitative analysis of single-nucleotide changes, insertions or deletions, gene copy number, infectious agents, and gene expression.