Serum concentration-guided intravenous magnesium sulfate administration for neuroprotection in patients with aneurysmal subarachnoid hemorrhage: a retrospective evaluation of a 12-year single-center experience.

Delayed cerebral infarction (DCI) is a major cause of morbidity and mortality in patients with aneurysmal subarachnoid hemorrhage (aSAH). The benefits of magnesium sulfate as an alternative treatment are controversial, and most previous studies examined its benefits only as adjunctive treatment to traditional nimodipine. We retrospectively analyzed aSAH patients records with magnesium sulfate between 2010 and 2021. We aimed for a serum magnesium concentration of 2-2.5 mmol/l between post-hemorrhage days 3 and 12. The patients were separated in three groups based on average serum magnesium concentration (magnesium >2 mmol/l, reduced magnesium 1.1-1.9 mmol/l, and no magnesium). Additionally, we assessed delayed cerebral infarction (DCI) and clinical outcome at follow-up, using the modified Rankin Scale (mRS), categorized in favorable (0-3) and unfavorable outcome (4-5). In this analysis, 548 patients were included. Hereof, radiological evidence of DCI could be found in 23.0% (n = 126) of patients. DCI rates were lower if patients' average serum magnesium was higher than 2 mmol/l (magnesium 18.8%, n = 85; reduced magnesium 38.3%, n = 23; no magnesium 51.4%, n = 18; p < 0.001). Also, at the last follow-up, patients in the group with a higher serum magnesium concentration had better outcome (favorable outcome: magnesium 64.7%, n = 293; reduced magnesium 50.0%, n = 30; no magnesium 34.3%, n = 12; p < 0.001). This 12-year study reveals the value of serum concentration-guided magnesium administration in aSAH patients. Our findings demonstrate the safety and efficacy when titrated to a serum concentration of 2-2.5 mmol/l. We observed higher rates of delayed cerebral infarction and unfavorable outcomes in patients with serum concentrations below 2 mmol/l.

First Report of Phytophthora cactorum and P. citrophthora Causing Root Rot of Ribes lobbii in Oregon.

Ribes lobbii (Gray) is a native, deciduous shrub from British Columbia, California, Oregon, and Washington that is grown for its pendulous red and white flowers, bristly fruit, and attractive, aromatic foliage. It is uncommon in nature and has only recently begun being propagated for sale in ornamental and native nurseries. In April 2013, 2-year-old containerized plants (15/50 plants) were found with severe wilt and chlorosis symptoms at a nursery production facility in western Oregon. Most fine roots were completely rotted and larger roots exhibited numerous black lesions. By the end of August, 50% of the plants were affected and most died within a few weeks of initial symptom development. At least three initially asymptomatic plants developed symptoms after being sold and planted. Isolation was attempted from 10 plants by plating pieces of necrotic root tissue (3 mm2) that had been surface disinfested for 1 min in 10% bleach and 1 min in 70% ethanol onto PARP medium (2). Eight Phytophthora isolates were recovered and identified as P. cactorum (seven isolates, GenBank Accession No. KM085441) and P. citrophthora (one isolate, KM085442) on the basis of morphology and 99 to 100% internal transcribed spacer (ITS) sequence similarity to published sequence data (1). One isolate of each species was used to prepare vermiculite inoculum (3) and subsequently to infest potting media (Sunshine Professional Growing Mix) at 100 propagules per gram. Due to the scarcity of R. lobbii in nature and the nursery trade, only a limited number of plants were available for pathogenicity tests. Three 1-year-old rooted cuttings of R. lobbii (~15 to 30 cm tall) were transplanted into individual 10-cm2 pots containing 175 g of the respective infested media for each pathogen. Three plants transplanted into individual pots of noninfested media served as negative controls. Plants were then watered to pot capacity and incubated in a greenhouse at 28/24°C day/night. The entire experiment was repeated 2 weeks later. Within 1 week after inoculation, all inoculated plants in both trials wilted and died, regardless of the Phytophthora species used; negative control plants remained healthy. Each pathogen (with identity confirmed by ITS sequence analysis) was re-isolated from the roots and stem of each respective inoculated plant, but was not isolated from negative controls, thus fulfilling Koch's postulates. Therefore, to my knowledge, this is the first report of P. cactorum and P. citrophthora as root rot pathogens of R. lobbii. The use of infected, but asymptomatic native plants in habitat restoration efforts will likely compromise success and there is considerable risk to nearby plant species given the broad host range of both pathogens. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) M. E. Kannwischer and D. J. Mitchell. Phytopathology 68:1760, 1978. (3) J. E. Weiland et al. Plant Dis. 97:744, 2013.

A key to improved ion core confinement in the JET tokamak: ion stiffness mitigation due to combined plasma rotation and low magnetic shear.

New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [Phys. Rev. Lett. 102, 175002 (2009)] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implications for the understanding of improved ion core confinement in advanced tokamak scenarios. Simulations using quasilinear fluid and gyrofluid models show features of stiffness mitigation, while nonlinear gyrokinetic simulations do not. The JET experiments indicate that advanced tokamak scenarios in future devices will require sufficient rotational shear and the capability of q profile manipulation.

Beyond Optical Depth: Future Determination of Ionization History from the Cosmic Microwave Background.

We explore the fundamental limits to which reionization histories can be constrained using only large-scale cosmic microwave background (CMB) anisotropy measurements. The redshift distribution of the fractional ionization x e (z) affects the angular distribution of CMB polarization. We project constraints on the reionization history of the universe using low-noise full-sky temperature and E-mode measurements of the CMB. We show that the measured TE power spectrum, C ^ ℓ TE , has roughly one quarter of the constraining power of C ^ ℓ EE on the reionization optical depth τ, and its addition improves the precision on τ by 20% over using C ^ ℓ EE only. We also use a two-step reionization model with an additional high-redshift step, parameterized by an early ionization fraction x e min , and a late reionization step at z re. We find that future high signal-to-noise measurements of the multipoles 10 ⩽ ℓ < 20 are especially important for breaking the degeneracy between x e min and z re. In addition, we show that the uncertainties on these parameters determined from a map with sensitivity 10 µK arcmin are less than 5% larger than the uncertainties in the noiseless case, making this noise level a natural target for future large sky area E-mode measurements.

Maize as a New Host for Oat blue dwarf virus.

Oat blue dwarf virus (OBDV) is a marafivirus present throughout the North American Great Plains and is found at low incidence levels in barley, oats, and flax in the Upper Midwest United States. Cropping patterns in this region have changed considerably in recent years, with much greater acreages devoted to maize in areas historically planted to small grains. Considering that OBDV is endemic in small grains in this region and that its aster leafhopper vector (Macrosteles quadrilineatus) is commonly detected in maize (2), we questioned whether maize might be a host for OBDV. Although Westdal (4) reported that maize was not a host for OBDV, it is the primary host for the related Maize rayado fino virus (MRFV) transmitted by Dalbulus maidis. MRFV is the type member of the marafiviruses and ranges from South America to the southern United States. To reevaluate the ability of maize to serve as a host for OBDV, viruliferous aster leafhoppers were allowed to feed on young maize seedlings for a 7-day inoculation access period. Plants were assayed for the presence of OBDV by ELISA 21 days after leafhopper removal. Initially, open-pollinated Sunglow sweet corn was tested in three experiments, with infection rates of 17 to 100%. A test of hybrid Sunglow resulted in 63% infection. These are comparable to transmission levels obtained when oat and barley plants are fed upon by viruliferous leafhoppers. Subsequently, 10 additional varieties of sweet and field corn were tested to determine if they could serve as hosts for OBDV. Sweet corn included Silver Queen, Peaches and Cream, Morning Star, Sugar Dots, Kandy Korn, and Golden Cross Bantam. Field corn included four lines provided by the maize breeding program of M. Carena at North Dakota State University (056640, 056643, 056612, and 056652). At least one plant was infected in all sweet and field corn varieties except 056612. Infected plants were largely asymptomatic, although a very faint stipple-striping was observed on some plants. To determine whether leafhoppers could acquire OBDV from infected maize and transmit the virus to other hosts, healthy leafhoppers were fed upon detached leaves of infected maize for 4 days (approximately 30 days after initial infection) and subsequently transferred three times at weekly intervals to barley and oats. Infection rates of 42 to 55% were observed in target plants, indicating efficient transmission from maize to other cereal hosts. The extent of natural infection of maize by OBDV or economic loss, if any, remains to be determined. This discovery extends the host range of OBDV to include maize and suggests that maize has the potential to serve as a natural reservoir for OBDV. The identification of hosts for known and new marafiviruses, such as those recently detected in citrus (3) and grape (1), will expand our understanding of the ecology and epidemiology of viruses within this group. References: (1) M. Al Rwahnih. Virology 387:395, 2009. (2) J. L. Capinera. Page 320 in: Encyclopedia of Entomology. 2nd ed. Springer Publishing, New York, NY, 2008. (3) W. Maccheroni et al. J. Virol. 79:3028, 2005. (4) P. Westdal. Can. J. Bot. 46:1431, 1968.

Protein permeability in the adult respiratory distress syndrome. Loss of size selectivity of the alveolar epithelium.

Small amounts of plasma protein normally reach the alveolar epithelial surface by a size-selective process that restricts the passage of very large molecules. Size selectivity may be compromised in the lungs of patients with the adult respiratory distress syndrome (ARDS). To assess this question, bronchoalveolar lavage fluid (BALF) from normal volunteers (n = 11), cardiac edema patients (n = 3), and ARDS patients (n = 8) was compared. Mean total protein in ARDS BALF was greater than 12 times the levels in normals or cardiac edema patients. BALF/plasma total protein ratios and measurements of epithelial lining fluid protein also separated the patients groups. The large proteins IgM and alpha 2-macroglobulin were found in ARDS BALF at greater than 90 times the concentrations of normal or cardiac edema fluid. The relationship of distribution coefficient vs. log molecular weight for seven proteins (54,000-900,000 mol wt) hyperbolically increased in normals but was flat in ARDS patients. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a paucity of high molecular weight proteins in normal and cardiac edema BALF, but demonstrated the full spectrum of plasma proteins in ARDS BALF. We conclude that normal size selectivity is preserved in cardiac edema but is destroyed by the alveolar-capillary injury of ARDS.

Testing stimulus protocols in retinal-prosthesis patients.

Retinal prostheses have demonstrated the capability to give blind patients the ability to detect motion and locate large objects. High-resolution retinal prostheses require precise activation of retinal cells to elicit a small visual phosphine that can serve as a building block to make patterns. Each electrode should activate only nearby cells, however patients receiving single electrode stimulation often report a streak-shaped phosphene rather than a focal spot. It is important to investigate stimulus paradigms that will provide better control over the spatial patterns of activation. During this study a 55 year old patient implanted with the Argus II system on August 2015 was tested with single electrode stimulation and pattern stimulation experiments. Tasks were performed using Argus II normal parameters.

Sawadaea tulasnei Powdery Mildew of Norway Maple (Acer platanoides) in North America.

Norway maple leaves bearing powdery mildew were collected from one location in the fall of 2003 and four locations (as much as 1.5 km apart) in the fall of 2005 in Buffalo, NY. No powdery mildew was observed on leaves collected from sugar maples (Acer saccharum) that were present in the vicinity of affected Norway maples at two locations. Trees were located along streets and in yards. Diseased leaves were present throughout tree crowns but lower leaves were more commonly affected. White mycelium was present in irregular, discrete, scattered spots only on the upper surface of leaves and on both sides of wings of samaras. Typically, <10% of the upper leaf area bore visible mycelium. Cleistothecia were present singly or in groups on the mycelium. Morphology of cleistothecia on leaves collected each year, including simple and bifid appendages with uncinate to circinate apices, was sufficient to identify the pathogen to the genus Sawadaea (1). Other characteristics were not sufficiently distinct to make an identification of S. bicornis or S. tulasnei (1), each a European species found on Acer spp. However, a sample from 2003 was supplied by the authors for use in a study of phylogeny of the genus (2) that served as a first report of the species in the United States. Analysis of nuclear rDNA ITS sequence of this specimen (GenBank Accession No. AB193390) placed the sample in a clade with S. tulasnei specimens from Europe. In the same study, powdery mildew samples from Acer spp. in Ohio and Montreal, Canada also were placed in this clade. Thus, occurrence of S. tulasnei in North America is confirmed. S. bicornis was recently identified (based on morphology) on Norway maple in the western United States (3). Specimens from Buffalo, NY have been deposited in the U.S. National Fungus Collections (BPI 871210). References: (1) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena-Stuttgart-New York, 1995. (2) S. Hirose et al. Mycol. Res. 109:912, 2005. (3) C. Nischwitz and G. Newcombe. Plant Dis. 87:451, 2003.

First Report of Beet black scorch virus in the United States.

In October of 2005, sugar beet (Beta vulgaris L.) plants exhibiting symptoms of rhizomania caused by Beet necrotic yellow vein virus (BNYVV) (3) were observed in a production field near Greeley, CO. The roots of seven plants exhibiting moderate to severe symptoms characteristic of this disease were tested using double-antibody sandwich enzyme-linked immunosorbent assay with anti-BNYVV antiserum from rabbits. Of these, only two roots exhibiting the mildest symptoms tested positive for BNYVV (all roots tested negative for the presence of the related Beet soilborne mosaic virus (BSBMV). 'Hairy' lateral roots characteristic of the disease were combined from the remaining five roots, ground in phosphate buffer, and the supernatant from the suspension was mechanically applied to leaves of Chenopodium quinoa in an effort to isolate an infectious agent. Five days postinoculation (dpi), yellow lesions with necrotic centers were visible on inoculated leaves, well in advance of those typically observed for BNYVV or BSBMV. Lesions exhibiting a similar rate of development on C. quinoa subsequently were induced from extracts of root vascular tissue prepared from four of seven additional beet roots tested from this location. Transfer of the infection from the C. quinoa lesions to 32 healthy C. quinoa and 10 sugar beet plants (hybrid ACH9369; American Crystal Sugar Co., Moorhead MN) resulted in 100% infection. Inoculated leaves of C. quinoa exhibited a high density of necrotic local lesions within 3 dpi, whereas inoculated leaves of sugar beet exhibited pinpoint, necrotic to diffuse, chlorotic local lesions evident by 5 dpi. Electron microscopic examination of fixed, ultra-thin sections of symptomatic C. quinoa leaf tissue revealed aggregates of virus-like particles of icosahedral symmetry within the cell cytoplasm. Following a virus minipreparation procedure, nucleic acid extracted from the partially purified virus was found to be single-stranded RNA by ribonuclease digestion and alone was infectious when inoculated to C. quinoa leaves. The apparently monopartite RNA genome was 3.5 kb long and a candidate for the single coat protein (CP) had a mass of ˜25 kDa. The sole reference set found in the literature for a virus naturally occurring on sugar beet with similar characteristics was that for Beet black scorch virus (BBSV), a virus recently accepted by the ICTV into the genus Necrovirus within the family Tombusviridae (2). Prior to this communication, BBSV has only been reported in China where it was first documented affecting sugar beet in the late 1980s (1). Using the published sequence of BBSV (Genbank Accession No. AY626780), DNA primers directed to the 3' half of the BBSV genome were used in reverse transcription-polymerase chain reaction to produce an amplicon from the unknown virus. Sequencing the amplicon revealed 88.8% nucleotide sequence identity to the BBSV CP gene and 97% amino acid sequence identity to the predicted CP gene product. Combined, the nucleotide sequence and physical characteristics confirm the presence of BBSV in a U.S. sugarbeet field for the first time. To our knowledge, this is the first report of the occurrence of BBSV outside of China. References: (1) Y. Cao et al. Arch. Virol. 147:2431, 2002. (2) C. M. Fauquet et al. Eighth Report of the International Committee on the Taxonomy of Viruses. Academic Press, New York, 2005. (3) C. M. Rush. Ann. Rev. Phytopathol. 41:567, 2003.

Evaluation of Effects of Electrical Stimulation in the Retina with Optical Coherence Tomography.

Retinal prostheses provide the capability to blind patients to detect motion and locate large objects. To avoid activating axons of passage, which can create streak-like perceptions, long pulse stimulation can be used to bypass axons and achieve focal retinal activation. Safety is a concern because long pulses require more charge than short pulses to elicit a response from neural tissue. Future implants will require smaller electrodes to improve resolution, but increased charge density may result, which is another safety concern. We developed a method to study the effects of electrical stimulation in the retina in real time using OCT (Optical Coherence Tomography) imaging combined with micropositioning of a stimulating electrode over the retina in an animal model. When using a 250-micron diameter electrode and stimulating for 30 minutes (frequency: 333 Hz), charge density: 1.22 mC/cm2, we observed an increase in retinal thickness from 154.3 µm ± 7.04 µm to 179.67 µm ± 0.47µm, a 16.66 % ± 5.49% increase compared to baseline. The region of increased thickness extended laterally for 0.56 mm ± 0.009 mm. When stimulating with a charge density of 1.63 mC/cm2, we observed an increase in retinal thickness from 160.3 µm ± 2.05 µm to 190 µm ± 0.81µm, a 19.52 % ± 1.86% increase compared to baseline. The region of increased thickness expanded laterally for 1.27 mm ± 0.19 mm.

Improved electrode material for deep brain stimulation.

Deep brain stimulation (DBS) devices have been implanted for treatment of basic tremor, Parkinson's disease and dystonia. These devices use electrodes in contact with tissue to deliver electrical pulses to targeted cells, to elicit specific therapeutic responses. In general, the neuromodulation industry has been evolving towards smaller, less invasive electrodes. However, current electrode materials do not support small sizes without severely restricting the stimulus output. Hence, an improved electrode material will benefit present and future DBS systems. In this study, five DBS leads were modified using a cost-effective and materials-efficient process for applying an ultra-low impedance platinum-iridium alloy coating. One DBS lead was used for insertion test and four DBS leads were chronically pulsed for 12 weeks. The platinum-iridium alloy significantly improved the electrical properties of the DBS electrodes and was robust to insertion into brain and to 12 weeks of chronic pulsing.

Long-term in vitro maintenance of clonal abundance and leukaemia-initiating potential in acute lymphoblastic leukaemia.

Lack of suitable in vitro culture conditions for primary acute lymphoblastic leukaemia (ALL) cells severely impairs their experimental accessibility and the testing of new drugs on cell material reflecting clonal heterogeneity in patients. We show that Nestin-positive human mesenchymal stem cells (MSCs) support expansion of a range of biologically and clinically distinct patient-derived ALL samples. Adherent ALL cells showed an increased accumulation in the S phase of the cell cycle and diminished apoptosis when compared with cells in the suspension fraction. Moreover, surface expression of adhesion molecules CD34, CDH2 and CD10 increased several fold. Approximately 20% of the ALL cells were in G0 phase of the cell cycle, suggesting that MSCs may support quiescent ALL cells. Cellular barcoding demonstrated long-term preservation of clonal abundance. Expansion of ALL cells for >3 months compromised neither feeder dependence nor cancer initiating ability as judged by their engraftment potential in immunocompromised mice. Finally, we demonstrate the suitability of this co-culture approach for the investigation of drug combinations with luciferase-expressing primograft ALL cells. Taken together, we have developed a preclinical platform with patient-derived material that will facilitate the development of clinically effective combination therapies for ALL.

Anisotropic diffusion across an external magnetic field and large-scale fluctuations in magnetized plasmas.

The problem of random motion of charged particles in an external magnetic field is studied under the assumption that the Langevin sources produce anisotropic diffusion in velocity space and the friction force is dependent on the direction of particle motion. It is shown that in the case under consideration, the kinetic equation describing particle transitions in phase space is reduced to the equation with a Fokker-Planck collision term in the general form (non-isotropic friction coefficient and nonzero off-diagonal elements of the diffusion tensor in the velocity space). The solution of such an equation has been obtained and the explicit form of the transition probability is found. Using the obtained transition probability, the mean-square particle displacements in configuration and velocity space were calculated and compared with the results of numerical simulations, showing good agreement. The obtained results are used to generalize the theory of large-scale fluctuations in plasmas to the case of anisotropic diffusion across an external magnetic field. Such diffusion is expected to be observed in the case of an anisotropic k spectrum of fluctuations generating random particle motion (for example, in the case of drift-wave turbulence).

Hemoptysis as the presenting manifestation of thyroid carcinoma. A case report.

An unusual case of a 61-year-old man who had hemoptysis as the major presenting manifestation of radiation-induced thyroid carcinoma is reported. The diagnosis was made by bronchoscopic removal of a polypoid lesion that was a direct extension of tumor through the trachea. Bronchoscopy is an effective and reliable means of establishing the diagnosis in this unusual subset of patients with thyroid carcinoma invading the trachea, and should be considered as the first diagnostic procedure in a patient with a thyroid mass and hemoptysis.

A single nucleotide substitution in the alpha a gene confers oat pathogenicity to barley stripe mosaic virus strain ND18.

A 236-nucleotide region from the alpha a gene of strain CV42 (pathogenic to oat), when substituted for the homologous region in strain ND18 (nonpathogenic to oat), was shown previously to confer a near wild-type oat pathogenicity to this strain (Weiland and Edwards, 1994, Virology 201: 116-126). The data suggested that six amino acid substitutions in the alpha a gene were responsible for the differences in oat pathogenicity, and that threonine-724, encoded by CV42, might be a critical amino acid in determining pathogenicity of barley stripe mosaic virus (BSMV) to oat. In the present work, codons specifying T-724, I-764, and N-785 (encoded by CV42 RNA alpha) were substituted individually and in combination for those coding for P-724, T-764, and K-785 (encoded by ND18 RNA alpha), respectively, by site-directed mutagenesis. The core K-733, T-734, and K-736 positions (CV42) were substituted for Q-733, S-734, and Q-736 (ND18) as a single block. The results of inoculations with these mutants indicate that the C2261-->A2261 nucleotide substitution (P-724-->T-724) by itself is sufficient to enable strain ND18 to infect oat plants, although poorly. Additional substitution of CV42 codons into ND18 RNA alpha at the remaining five positions altered symptom type, decreased the timing of the appearance of symptoms, and increased the percentage of plants infected per inoculation. Nonetheless, all mutants accumulated to similar levels in inoculated oat protoplasts after a 24-h period. Using a recombinant RNA beta from which beta-glucuronidase could be expressed, results were obtained suggesting that the multiplication of strain ND18 and the nonpathogenic variants generated in the study was restricted in the inoculated leaf. The data indicate a potential pathway by which pathogenicity to oat evolved in BSMV.

Location and properties of the digitalis receptor site in Na+/K(+)-ATPase.

Since 1985, several research groups have shown that a number of amino acids in the catalytic alpha-subunit of Na+/K(+)-ATPase more or less strongly modulate the affinity of a digitalis compound like ouabain to the enzyme. However, scrutiny of these findings by means of chimeric Na+/K(+)-ATPase constructs and monoclonal antibodies has recently revealed that the modulatory effect of most of these amino acids does not at all result from direct interaction with ouabain, but rather originates from long-range effects on the properties of the digitalis binding matrix. Starting from this knowledge, the present review brings together the various pieces of evidence pointing to the conclusion that the interface between two interacting alpha-subunits in the Na+/K(+)-ATPase protodimer (alpha beta)2 provides the cleft for inhibitory digitalis intercalation.

Long-term histological and electrophysiological results of an inactive epiretinal electrode array implantation in dogs.

PURPOSE: Short-term pattern electrical stimulation of the retina via multielectrode arrays in humans blind from photoreceptor loss has shown that ambulatory vision and limited character recognition is possible. To develop an implantable retinal prosthesis that would provide useful vision, these results need to be sustained over a prolonged period of retinal electrical stimulation. As a first step toward this goal, the biocompatibility and the feasibility of surgically implanting an electrically inactive electrode array onto the retinal surface was tested. METHODS: A 5 x 5 electrode array (25 platinum disc-shaped electrodes in a silicone matrix) was implanted onto the retinal surface using retinal tacks in each of the 4 mixed-breed sighted dogs. Color fundus photography, fluorescein angiography, electroretinography, and visual evoked potentials were obtained preoperatively, at 1-week intervals for 2 weeks postoperatively, then at 2-week intervals up to 2 months postoperatively, and thereafter at 1-month intervals. One dog was killed at 2 months after implantation and a second dog after 3 months of implantation. Histologic evaluation of the retinas was performed. The remaining two dogs continue to be followed beyond 6 months after the implantation surgery. RESULTS: No retinal detachment, infection, or uncontrolled intraocular bleeding occurred in any of the animals. Retinal tacks and the retinal array remained firmly affixed to the retina throughout the follow-up period. Hyperpigmentation of the retinal pigment epithelium was observed only around the site of retinal tack insertion. No fibrous encapsulation of the implant or intraocular inflammation was visible. A- and b-wave amplitudes of the electroretinogram were depressed at the first postoperative week testing but recovered over the ensuing 1 week and were not statistically different from the normal unoperated fellow eye throughout the postoperative period. N1 and P1 wave amplitudes of the visual evoked potentials were not significantly different from the normal fellow eyes at any of the postoperative test intervals. Fluorescein angiography showed that the entire retina including the area under the electrode array remained well perfused. Similarly, histologic evaluation revealed near total preservation of the retina underlying the electrode array. CONCLUSIONS: Implantation of an electrode array on the epiretinal side (i.e., side closest to the ganglion cell layer) is surgically feasible, with insignificant damage to the underlying retina. The platinum and silicone arrays as well as the metal tacks are biocompatible. With the success of implanting an electrically inactive device onto the retinal surface for prolonged periods, the effects of long-term retinal electrical stimulation are now ready to be tested as the next step toward developing a prototype retinal prosthesis for human use.

Light-driven retinal ganglion cell responses in blind rd mice after neural retinal transplantation.

PURPOSE: Light-elicited retinal ganglion cell (RGC) responses after fetal neural retinal transplantation have not been demonstrated in animal or human subjects blind from outer retinal degeneration, despite apparent morphologic success. This study was designed to test the hypothesis that the functional success of retinal transplantation may be enhanced by using a young host retina (13 days old). METHODS: At postnatal day (P)13 C3H/HeJ (rd/rd) retinal degenerate mice received a subretinal transplant, in one eye only, of neural retinal tissue isolated from newborn normal C57/BL6J mice. Between 33 and 35 days after transplantation, local electroretinograms (ERGs) and ganglion cell responses were recorded directly from the retinal surface using a differential bipolar surface electrode. Measurements were performed both with and without light stimulation. Similar recordings were also performed in age-matched eyes subjected to sham transplantation, in control eyes that were not subjected to surgery, and in animals eyes that underwent transplantation at 8 weeks of age. After the recordings, the eyes were processed for light and transmission electron microscopy. RESULTS: Three of 10 mice showed bursts of ganglion cell action potentials (ON response only) as well as recordable intraocular ERGs over the transplant in response to 1-second and 200-msec light stimuli. Light-driven ganglion cell responses could not be recorded in areas outside the transplant in all transplant-recipient eyes, age-matched control eyes, and sham-transplantation eyes. Light responses also could not be recorded in animal eyes that received transplants at an older age (8 weeks). Electron microscopic examination confirmed the presence of photoreceptor outer segments in the areas affected by transplantation. CONCLUSIONS: This study demonstrates the presence of light-driven ganglion cell responses after subretinal transplantation in a retinal degenerate model. This finding may reflect functional integration of the transplant with the host, but a rescue effect on remaining host photoreceptors cannot be ruled out. The findings suggest, however, that modification of host parameters, such as host age, may be important approaches for improving the functional success of retinal transplantation.

Origin of differences of inhibitory potency of cardiac glycosides in Na+/K+-transporting ATPase from human cardiac muscle, human brain cortex and guinea-pig cardiac muscle.

The inhibitory potency of altogether 95 steroidal compounds (including cardenolides, bufadienolides and their glycosides) on the Na/K-ATPases (Na+/K+-transporting ATPases, EC 3.6.1.37) from human cardiac muscle, human brain cortex and guinea-pig cardiac muscle was compared to probe the complementary chemotopology of the inhibitor binding site areas on the three enzyme variants. The changes of potency, resulting from systematic variations of the geometry of steroid skeleton and the character as well as the structure of side chains at C3 or/and C17 of steroid backbone, allowed the following major conclusions. With the human cardiac and cerebral enzyme forms, the paired K0.5 (K'D) values for 77 steroid derivatives, covering seven orders of ten, were highly correlated. On an average, the total of compounds showed a 1.5-fold higher affinity to the cardiac enzyme. This tiny differentiation did not appear to be connected with an important difference in the chemotopology of the complementary subsites for steroid nucleus binding on the two enzyme forms. With the human and guinea-pig cardiac enzyme variants, the K0.5 values for 69 steroid derivatives, covering six orders of ten, were determined. For 41 5 beta, 14 beta-androstane derivatives only, the paired K0.5 values showed a close correlation. Here, the human enzyme variant exhibited 27-fold higher affinity. However, the paired K0.5 values determined on both enzymes for 28 steroid derivatives of differing structural features were but poorly correlated. Essentially, the geometries of the steroid nucleus determined the differential contributions of the side chains at C3 and C17 to the integral inhibitory potency on the two enzyme variants. Thus, the species differences in the potency of cardiac glycosides were traced to species differences in the complementarity of the steroid binding subsites. Hence, estimates of the potency of new steroidal compounds obtained on the guinea-pig cardiac enzyme can be neither quantitatively nor qualitatively easily extrapolated to the human cardiac enzyme. The extrathermodynamic analysis of the data opened major new insights in the structure-activity relationships concerning the role of C14 beta-OH, the character of the lead structure in cardioactive steroid lactones, and the significance of the configuration of A/B ring junction.