Morphometric assessment of normal, suspect and glaucomatous optic discs with Stratus OCT and HRT II

AIMS: To compare morphometric parameters and diagnostic performance of the new Stratus Optical Coherence Tomograph (OCT) Disc mode and the Heidelberg Retina Tomograph (HRT); to evaluate OCT's accuracy in determining optic nerve head (ONH) borders. METHODS: Controls and patients with ocular hypertension, glaucoma-like discs, and glaucoma were imaged with OCT Disc mode, HRT II, and colour disc photography (DISC-PHOT). In a separate session, automatically depicted ONH shape and size in OCT were compared with DISC-PHOT, and disc borders adjusted manually where required. In a masked fashion, all print-outs and photographs were studied and discs classified as normal, borderline, and abnormal. The Cohen kappa method was then applied to test for agreement of classification. Bland-Altman analysis was used for comparison of disc measures. RESULTS: In all, 49 eyes were evaluated. Automated disc margin recognition failed in 53%. Misplaced margin points were more frequently found in myopic eyes, but only 31/187 were located in an area of peripapillary atrophy. Agreement of OCT with photography-based diagnosis was excellent in normally looking ONHs, but moderate in discs with large cups, where HRT performed better. OCT values were consistently larger than HRT values for disc and cup area. Compared with HRT, small rim areas and volumes tended to be minimized by OCT, and larger ones to be magnified. CONCLUSIONS: Stratus OCT Disc protocol performed overall well in differentiating between normal and glaucomatous ONHs. However, failure of disc border recognition was frequently observed, making manual correction necessary. ONH measures cannot be directly compared between HRT and OCT.

Quantitative magnetic resonance imaging of enzymatically induced degradation of the nucleus pulposus of intervertebral discs

STUDY DESIGN: The structural integrity of the nucleus pulposus (NP) of intervertebral discs was targeted by enzyme-specific degradations to correlate their effects to the magnetic resonance (MR) signal. OBJECTIVE: To develop quantitative MR imaging as an accurate and noninvasive diagnostic tool to better understand and treat disc degeneration. SUMMARY OF BACKGROUND DATA: Quantitative MR analysis has been previously shown to reflect not only the disc matrix composition, but also the structural integrity of the disc matrix. Further work is required to identify the contribution of the structural integrity versus the matrix composition to the MR signal. METHODS: The bovine coccygeal NPs were injected with either enzyme or buffer, incubated at 37 degrees C as static, unloaded and closed 3-disc segments, and analyzed by a 1.5-Tesla MR scanner to measure MR parameters. RESULTS: Collagenase degradation of the NP significantly decreased the relaxation times, slightly decreased the magnetization transfer ratio, and slightly increased the apparent diffusion coefficient. Targeting the proteoglycan and/or hyaluronan integrity by trypsin and hyaluronidase did not significantly affect the MR parameters, except for an increase in the apparent diffusion coefficient of the disc after trypsin treatment. CONCLUSIONS: Our results demonstrate that changes in the structural integrity of matrix proteins can be assessed by quantitative MR.

Nitric oxide synthase protein levels, not the mRNA, are downregulated in olfactory bulb interneurons of reeler mice

Homozygous mutations in the Reelin gene result in severe disruption of brain development. The histogenesis of layered regions, like the neocortex, hippocampus and the cerebellum, is most notably affected in mouse reeler mutants and similar traits are also present in mice lacking molecular components of the Reelin signalling pathway. Moreover, there is evidence for an additional role of Reelin in sustaining synaptic plasticity in adult networks. Nitric oxide is an important gaseous messenger that can modulate neuronal plasticity both in developing and mature synaptic networks and has been shown to facilitate synaptic changes in the hippocampus, cerebellum and olfactory bulb. We studied the distribution and content of neuronal nitric oxide synthase in the olfactory bulbs of reeler and wildtype mice. Immunocytochemistry reveals that Reelin and neuronal nitric oxide synthase containing interneurons are two distinct, non overlapping cell populations of the olfactory bulb. We show by in situ hybridization that both nitrergic and Reelin expressing cells represent only a subset of olfactory bulb GABAergic neurons. Immunoblots show that neuronal nitric oxide synthase protein content is decreased by two thirds in reeler mice causing a detectable loss of immunolabelled cells throughout the olfactory bulb of this strain. However, neuronal nitric oxide synthase mRNA levels, essayed by quantitative real-time RT-PCR, are unaffected in the reeler olfactory bulb. Thus, disruption of the Reelin signalling pathway may modify the turnover of neuronal nitric oxide synthase in the olfactory bulb and possibly affects nitric oxide functions in reeler mice.

Olfactory bulb interneurons releasing NO exhibit the Reelin receptor ApoEr2 and part of those targeted by NO express Reelin

Nitric oxide (NO) and Reelin both modulate neuronal plasticity in developing and mature synaptic networks. We recently showed a loss of neuronal nitric oxide synthase (nNOS) protein in the olfactory bulb of reeler mutants and advanced the hypothesis that the Reelin and NO signalling pathways may influence each other. We now studied the distribution of NO sensitive guanylyl cyclase (NOsGC), Reelin and its receptor Apolipoprotein E2 (ApoEr2) in the olfactory bulb by multiple fluorescence labelling and tested whether nNOS and ApoEr2 colocalize in this area. We also essayed the protein content of NOsGC in the reeler olfactory bulb and tested whether there are any changes in nNOS and NOsGC protein in other reeler brain areas. Olfactory bulb interneurons expressing ApoEr2 and nNOS are only few in the glomerular layer but represent the large majority of granule cell layer interneurons. Conversely, NOsGC interneurons are rare in the granule cell layer and abundant as periglomerular cells. Reelin containing periglomerular cells almost entirely belong to the NOsGC subset. These data further support the hypothesis of a reciprocal signalling between Reelin/NOsGC and ApoEr2/nNOS expressing neurons to affect olfactory bulb activity. We also show that a significant rise in NOsGC content accompanies the decrease of nNOS protein in the reeler olfactory bulb. The same reciprocal changes present in the cortex/striatum and the hippocampus of reeler mice. Thus, the influence that the deficit of extracellular Reelin seems to exert on nNOS and its receptor is not limited to the olfactory bulb but is a general feature of the reeler brain.

Expression of adenosine A2a receptors gene in the olfactory bulb and spinal cord of rat and mouse

The expression of adenosine A2a receptors (A2aR) in the mammalian striatum is well known. In contrast the exact distribution of A2aR in other regions of the central nervous system remains unclear. The aim of this study was to investigate the A2aR gene expression in the rat olfactory bulb and spinal cord, two regions which are seldom included in mapping studies. Secondly, we compared the A2aR expression in the rat and in the mouse brain. Hybridization histochemistry was performed with an S35-labelled radioactive oligonucleotide probe. The results show strong expression of A2aR in the mouse and rat striatum in accordance with previous reports. In the olfactory bulb a weak but specific expression of A2aR was found in the granular cell layer in both species. In contrast, no significant expression of the A2aR gene was observed in other parts of the brain or the rat spinal cord. The presence of the A2aR in the mammalian olfactory bulb suggests a functional role for this receptor in olfaction.

IMPROVING FLOW DISTRIBUTION IN SMALL-SCALE WATER-SUPPLY SYSTEMS THROUGH THE USE OF FLOW-REDUCING DISCS AND METHODS FOR ANALYZING THE EFFECTIVENESS OF SOLAR POWERED PUMPING FOR A DRINKING WATER SUPPLY IN RURAL PANAMA

As continued global funding and coordination are allocated toward the improvement of access to safe sources of drinking water, alternative solutions may be necessary to expand implementation to remote communities. This report evaluates two technologies used in a small water distribution system in a mountainous region of Panama; solar powered pumping and flow-reducing discs. The two parts of the system function independently, but were both chosen for their ability to mitigate unique issues in the community. The design program NeatWork and flow-reducing discs were evaluated because they are tools taught to Peace Corps Volunteers in Panama. Even when ample water is available, mountainous terrains affect the pressure available throughout a water distribution system. Since the static head in the system only varies with the height of water in the tank, frictional losses from pipes and fittings must be exploited to balance out the inequalities caused by the uneven terrain. Reducing the maximum allowable flow to connections through the installation of flow-reducing discs can help to retain enough residual pressure in the main distribution lines to provide reliable service to all connections. NeatWork was calibrated to measured flow rates by changing the orifice coefficient (θ), resulting in a value of 0.68, which is 10-15% higher than typical values for manufactured flow-reducing discs. NeatWork was used to model various system configurations to determine if a single-sized flow-reducing disc could provide equitable flow rates throughout an entire system. There is a strong correlation between the optimum single-sized flow- reducing disc and the average elevation change throughout a water distribution system; the larger the elevation change across the system, the smaller the recommended uniform orifice size. Renewable energy can jump the infrastructure gap and provide basic services at a fraction of the cost and time required to install transmission lines. Methods for the assessment of solar powered pumping systems as a means for rural water supply are presented and assessed. It was determined that manufacturer provided product specifications can be used to appropriately design a solar pumping system, but care must be taken to ensure that sufficient water can be provided to the system despite variations in solar intensity.

Reduced olfactory bulb volume in adults with a history of childhood maltreatment

The human olfactory bulb (OB) is the first relay station of the olfactory pathway and may have the potential for postnatal neurogenesis in early childhood. In animals, chronic stress affects the OB and olfactory functioning. For humans, it has been shown that major depressive disorder is accompanied by reduced OB volume and reduced olfactory function. However, it is not clear if major stress in childhood development also affects olfactory functioning and OB volume in humans. OB volume was measured and olfactory function was tested in 17 depressive patients with and 10 without a history of severe childhood maltreatment (CM). CM patients exhibited a significantly reduced olfactory threshold and identification ability. The OB volume of the CM patients was significantly reduced to 80% of the non-CM patients. In conclusion, postnatal neurogenesis might be by reduced in CM, which may affect olfactory function of the brain in later life. Alternatively, a reduced OB volume may enhance psychological vulnerability in the presence of adverse childhood conditions although other areas not analyzed in this study may also be involved.