Crosslinking of Cotton Cellulose in the Presence of Alpha-Amino Acids: Part II: Reaction Kinetics of the Mixed Reagents
ABSTRACT
Two kinds of alpha-amino acids are used to combine with dimethylol-dihydroxyethyleneurea (DMDHEU) as crosslinking agents, and the specific rate constants and other activation parameters are discussed. Prom the results, we find that the rate constants for the various crosslinking agent systems are in the order of DMDHEU > DMDHEU-aspartic acid > DMDHEU-glutamic acid. The energies needed to crosslink are in the rank of DMDHEU-glutamic acid > DMDHEU-aspartic acid > DMDHEU. The values of enthalpy and entropy for DMDHEU are lower than those for DMDHEU-alpha-amino acids, and enthalpy values for DMDHEU are significantly lower than those for DMDHEU-alpha-amino acids. The data of various activation parameters reveal that the reaction state of DMDHEU-alpha-amino acids is different from that of DMDHEU. Additionally, the reactions between aluminum sulfate and aspartic acid are confirmed by infrared spectra.
Our previous study [4, 13] showed that the -OH groups of both cellulose and dimethyloldihydroxyethyleneurea (DMDHRU) can react with the vinyl and/or epoxy group of alkyl di-allyl ammonium salts and the -COOH and -NH^sub 2^ of alpha-amino acids in the pad-dry-cure process. The physical properties and surface migration of DMDHEU-alkyl di-allyl ammonium salts and DMDHEU-alpha-amino acids are different from those for DMDHEU. It is well known that reaction rate constants are affected by varying the functional groups on crosslinking agents [1, 2, 7, 15]. Our recent study [5] showed that adding alkyl di-allyl ammonium salts to the aqueous solutions of DMDHEU did change the activation parameters of the crosslinking reaction.The effects of adding various alpha-amino acids in the aqueous padding solution of DMDHEU on the crosslinking reaction are interesting. Detailed information of the specific rate constants and other activation parameters for the DMDHEU-alpha-amino acids and DMDHEU treated fabrics is lacking. In this paper, we examine and discuss those activation parameters calculated using the method described by Ziifle et al. [2, 15].
Experimental
In this study, we used desized, scoured, and bleached cotton fabric with 60 ends (20’s) and 60 picks (20’s). The crosslinking agents were DMDHEU (dimethyloldihydroxyethyleneurea) and alpha-amino acids of aspartic acid and glutamic acid. Aluminum sulfate was reagent grade, as were the other chemicals.
For reaction kinetic studies, the cotton fabric samples were padded twice to about 90% wet pick-up with freshly prepared DMDHRU-alpha-amino acid solutions (0.36M, the mole ratio of DMDHEU to alpha-amino acids was 3 to 1) in the presence of the aluminum sulfate catalyst (0.036M). An queous padding solution of DMDHEU alone was also used for comparison. In order to obtain the changes in the bound nitrogen contents of the heated fabrics with the heating temperatures, padded fabric samples were heated at 80, 90, and 100°C for different time intervals, then soaped, washed, and dried. Nitrogen contents were determined using the Kjeldahl method.
Infrared spectra of the samples were obtained with a KBr disk technique [10]. Samples were prepared to a dry weight of 1.8 mg after storage in 1-dram vials over P^sub 2^O^sub 5^ for 3 days. Spectral-grade KBr (250-300 mg) was ground, transferred to individual sample vials, dried in an oven at approximately 200°C for several hours, and stored in an oven at 110°C. Samples were ground and mixed with the KBr and pressed in an evacuated die under suitable pressure. The IR spectra of aluminum sulfate, aspartic acid, and cured aluminum sulfate-aspartic acid (0.5 to 1 mole ratio of aluminum sulfate to aspartic acid was mixed, dissolved in water, then coated on a piece of glass and dried at 80°C) were examined to confirm the interaction of aluminum ion with the aspartic acid molecule in this study.
Results and Discussion
The data in Table 1 show the changes in the nitrogen content of cotton fabrics treated with DMDHEU-aspartic acid (sample, 1), DMDHEU-glutamic acid (sample 1), and DMDHEU (sample 0) with heating time. All samples were catalyzed by aluminum sulfate. The table reveals that the nitrogen contents of the treated fabrics increase with increased heating time for all cases. Figures 1, 2, and 3 show the relationships between the nitrogen contents and heating time intervals at different heating temperatures for samples 0, 1, and 2, respectively. The initial shape of slightly concave upward in all cases, which can be attributed to the time needed to raise the temperature of the fabric in the oven [2, 12]. The lower nitrogen bonded on the cotton fabrics for the DMDHEU-alphaamino acid crosslinking agents clearly reveal that the reaction between alpha-amino acids and cellulose molecules (and/or DMDHEU molecule) takes place only a little in the kinetic runs.
Semilogarithmic plots of (%N^sub 0^ - %N)/%N^sub 0^ versus heating time are shown in Figures 4-6 for samples 0, 1, and 2, respectively. %N^sub 0^ is the nitrogen content of the treated fabric after the pad-dry-cure process-padded to 90% wet pick-up, dried at 80°C for 5 minutes, and cured at 135°C for 3 minutes; the samples are thought to be fully cured at these conditions [8, 9]. %N is the bound nitrogen after a given time interval at the temperature indicated (80, 90, and 100°C). For all cases, straight lines are obtained, the linearity indicating that the reaction is pseudo-first-order for the time shown.
Inspection System suits solid dose pharmaceuticals
Vantyx(TM) performs 100%, in-line inspection of tablets, capsules, and softgels at full production speeds using Spatial Color Analysis technology. Able to verify product color, count, shape, position, and presence of print via 2-6 color cameras, it removes foreigners, color errors, shape defects, and missing doses to ensure dose conformity. It can be embedded within other packaging machinery and inspects up to 10,000 individual tablets/min or up to 360 complete blisterpacks/min. October 4, 2005 - SYMETIX, the Pharmaceutical Business Unit of Key Technology, introduces Vantyx(TM), a high-performance inspection system for tablets, capsules, and softgels. Vantyx achieves 100 percent, in-line inspection at full production speeds using Key’s patented SCA(TM) (Spatial Color Analysis) technology, which provides the industry’s highest color and spatial resolution. With unmatched precision, Vantyx verifies product color, count, shape, position, and presence of print and removes foreigners, color errors, shape defects, and missing doses to assure every dose conforms to product requirements. Vantyx enables pharmaceutical manufacturers to achieve the highest level of diligence while maximizing throughput.
Vantyx is FDA 21 CFR part 11 compliant, designed to meet GAMP 4 requirements, and benefits from Key Technology’s 10-year history of supplying FDA-validated inspection solutions to the pharmaceutical industry and 50-year history of supplying innovative technology to the food industry. SYMETIX offers complete engineering services and validation packages.
The compact and flexible Vantyx inspection system can be embedded within other packaging machinery such as blisterpack thermoformers, flat bed printers, and slat fillers. SYMETIX can also supply Vantyx as a stand-alone, bulk-to-bulk high volume inspection system. The technology is capable of inspecting up to 10,000 individual tablets, capsules, or softgels per minute, or as many as 360 complete blisterpacks per minute.
Vantyx ensures accurate product identification and product integrity to maximize pharmaceutical manufacturers’ diligence in assuring product quality while running at full production speeds. Vantyx also serves to monitor upstream production processes, which allows manufacturers to address the FDA ’s Process Analytic Technology (PAT) guidelines for physical characteristics of the product.
SYMETIX can equip Vantyx with two to six high-resolution color cameras, depending on the needs of the application. With up to six cameras, Vantyx can simultaneously inspect up to six different packages or six separate arrays of product. Each camera uses a dedicated image processor for maximum speed and image resolution.
About SYMETIX
SYMETIX, launched in September 2005, is the Pharmaceutical Business Unit of Key Technology, the leading manufacturer of best-in-class process automation systems with over 50 years of experience in the food, tobacco, and pharmaceutical industries. SYMETIX offers worldwide sales representation and maintains demonstration and testing facilities at Key’s headquarters and manufacturing divisions in Walla Walla, Washington, USA, and at Key Technology BV in Beusichem, the Netherlands.
MGI Pharma Inc. to Buy Guilford Pharmaceuticals for 3.71 Times Revenue
The Deal: MGI Pharma Inc. has agreed to acquire Guilford Pharmaceuticals in a cash and stock transaction valued at $177.5 million. Under the terms of the agreement, each share of Guilford stock will be exchanged for S1.13 in cash and $2.62 worth of MGI Pharma stock, for a combined value of $3.75 per share. MGI will also assume about $70 million in debt as part of the transaction. The deal is expected to close in October, subject to shareholder approvals.
Discussion: Guilford Pharmaceuticals develops medicines for the treatment of neurological diseases. The company also makes drug-delivery systems used for treating cancer. Guildford produces a special wafer designed to be placed in the space created after a brain tumor is removed. The wafer releases chemotherapy agents to help prevent the cancer from returning.
MGI Pharma buys and develops drugs, focusing primarily on medications for small medical niches. The company generally seeks to acquire drug candidates past the initial discovery stage, to reduce the risk of product failure. MGI’s current drug products help alleviate side-effects from various cancer treatments such as post-chemotherapy nausea and vomiting.
The acquisition will provide MGI with new products and its third production facility. MGI stated that it intends to maintain Guilford’s operations and retain many of its employees.
Recipe for success: smart partnering can transform a lone inventor into a market force
PRODUCT DESCRIPTION: Karyo’s company produces a line of silicone bakeware cooking tools with superior heat transfer and nonstick properties. The odor-resistant products, priced from $15 to $25 apiece, let users bake more efficiently, thanks to such features as even cooling and heat distribution. Silicone products had been used in commercial kitchens previously, but Karyo was the first to create a consumer line.
. FIND A VOID IN THE MARKET. “I was working as a consultant to develop a kitchenware [line] for a company that primarily sold silicone products to the medical industry,” says Karyo of how he uncovered this market opportunity. “I found that, while several European companies were selling silicone products to the commercial market, no one had a true consumer product. I felt that consumers and home bakers could benefit from silicone technology. I verified [this] with buyers for kitchen stores.” But by that time, the company he consulted for had changed its mind about entering the market, so Karyo went out on his own to develop a silicone line. The typical drawback to filling a market void is that you have to create a market for your product. Fortunately, Karyo didn’t have to deal with this obstacle–the existing popularity of silicone in commercial kitchen markets convinced buyers to give Karyo’s products a try.
2. DETERMINE HOW TO STAY IN A LEADING MARKKET POSITION. Karyo knew that being first to market wouldn’t be enough for him to remain a market leader. “I felt from the beginning that the key to staying on top in the market was to have ‘better than them’ product quality, unique designs and moderate prices that would give us a competitive advantage over much bigger housewares companies,” he says. So Karyo expanded his vision to include features that would differentiate his product from competitors: “The surface of SiliconeZone products is high gloss, not matte, and the product comes in vibrant colors that competitors can’t duplicate.”
3. IF NECESSARY, FIND A PARTNER. Karyo is a sales and marketing person–not a manufacturer. The high quality he was after called for manufacturing expertise and a willingness to help develop the product. Karyo knew he couldn’t afford to pay someone for development, nor could he afford to buy from a factory as a customer and keep prices down. “I knew I needed a partner company experienced in silicone,” says Karyo. “I talked to my father, Maurice, who had done business in the Far East for 40 years. He [found] a company in Hong Kong that made silicone products for the electronics industry. We formed a 50/50 joint venture with the owners, Ken and Ricky Yeung, where [they paid] development and tooling costs, while I paid for sales and marketing. Then we split the profits.” If you don’t have a connection to find a source you need, go online or to your local library to check out the Thomas Register of American Manufacturers, which lists manufacturers you can talk to about potentially setting up a partnership.
4. SELL THE MARKET ON WHY YOUR PRODUCTS IS THE CLEAR CHOICE. With some products, customers can tell right away which product is best based on visual clues, such as fit and finish, expensive materials or packaging. But in Karyo’s case, buyers didn’t understand that his product was of higher quality. So Karyo gave them a straightforward pitch: “I showed buyers the factors that determined a quality product.” He pushed three main differentiating factors: the high quality of his proprietary silicone formula, a denser and heavier product that provides better heat conductivity; the high-gloss finish, which calls for a slower production process and hand-polished tooling; and the vibrancy of the color, which results from using high-quality silicone material and pigments.
5. STRENGTHEN YOUR BRAND. Karyo ran an ad campaign to get the word out about his business. “We didn’t have any sales, but I wanted buyers of independent stores and major retailers to know and remember that we were the first ones in the market,” he says. “I took out ads in key trade magazines like HFN (Home Furnishing News), Home World Business and Kitchenware News.” He says people still remark to him at shows, “I remember you being the first in the market
In my Garment there is nothing but God: recent work by Ibrahim el Salahi
Ibrahim el Salahi was born in the Sudan in 1930, and is widely recognized as one of the progenitors of modern painting in that country. (1) He studied in Khartoum at the School of Design Gordon Memorial College, in London at the Slade School, and then returned to the Sudan to teach. (2) Briefly imprisoned under Nimeiri in 1975, el Salahi left the Sudan upon his release and he has since been in self-imposed exile in Qatar and Oxford, England.
Salah Hassan has divided el Salahi’s oeuvre into three periods–an early period (late 1950s-1970s) characterized by muted, earthy tones and a linear compositional style; a second period (late 1970s) with more vibrant colors and “abstract human and animal-like figures rendered in geometric design”; and a third phase (late 1970s to present) in which works are mainly in black and white (Hassan 1998:31-2). This discussion of the artist’s work, however, addresses currents that run through these divisions. Specifically, el Salahi’s own narration of his career trajectory reveals a consistent interest in negotiating and bridging the distance between his body and his work. He considers the process of coming to the canvas or paper as the meeting of two bodies and subjectivities–his own and the canvas’s–and the work then grows from a conversation (and sometimes an argument) between the two. This negotiation takes place throughout his career at several levels–through prayer and meditation, media, compositional construction, and imagery. Further, el Salahi’s attempts to link his own body (as a creator) to the work (as a creation) shift slowly over time from engagement with the exterior, physical body to representations of an interior, spiritual body. This transformation in turn mirrors his ongoing use of prayer and meditation as a means to bring himself closer to God.
Rather than limit art historical engagement to the formal development of el Salahi’s works, this analysis of his oeuvre draws upon embodied models that are more often applied to the study of performance arts in Africa, such as masquerades (see, for example, Bourdieu 1977 and Connerton 1989). The use of such models widens the scope of analysis and allows us to more thoroughly consider the artist’s physical experience of creation in both the phenomenological and spiritual sense. Additional meaning is drawn from the artist’s implicit bodily performances over time. Within such a framework, the borders of what constitutes the “work” expand, and the drawings and paintings themselves are recast as fragments of a broader, equally significant, and ongoing embodied experience.
Prayer
El Salahi is a Muslim of a Sufi sect and notes that he prays five times a day and will often pray again before he starts to draw or paint. (3) This has been true throughout his life, except for a brief period when he was enrolled in a British school in the Sudan. El Salahi’s definition of prayer and his discussion of its role in his work is significant. In one interview, he described the process of washing, preparing his body before prayer, the motions he goes through as he prays which distract him from his surroundings, the words he speaks, and what they mean.
Leaf Science: Pigments on Parade! - Brief Article - Statistical Data Included
With the beginning of autumn, the leaves of deciduous trees seem to magically turn an incredible natural palette of yellow, brown, orange, and red. Your students can discover for themselves how these “hidden colors” materialize in leaves by doing a simple experiment in paper chromatography.
Color Activity
Every grade-schooler knows about mixing paints together to get new colors. In this experiment, your students will do the opposite, taking pigments apart to see what colors emerge. Encourage your class to predict what colors may be present in different water-based markers and then test their hypotheses.Give students four 1″-wide strips of paper towel each and ask them to select 4 different colors of marker, one for each strip. Next they draw a single line lengthwise from the top and stop 1″ from the bottom.
* Ask students to dip the bottom edge of their paper strips into small cups of water. As the water is absorbed by the paper strip, the pigments will begin to flow up the strip, slowly separating into their component colors.
* Tie this activity back into the idea of changing leaves by asking students why different trees turn different colors.
* Your students can create an autumn art project with leaf shapes cut from paper towels. Ink a large brown dot in the center of each leaf, and use a dropper to apply water to the paper. The result will be an array of unique and colorful leaves.
Ground and Excited States of Retinal Schiff Base Chromophores by Multiconfigurational Perturbation Theory
We have studied the wavelength dependence of retinal Schiff base absorbencies on the protonation state of the chromophore at the multiconfigurational level of theory using second order perturbation theory (CASPT2) within an atomic natural orbital basis set on MP2 optimized geometries. Quantitative agreement between calculated and experimental absorption maxima was obtained for protonated and deprotonated Schiff bases of all-trans- and 11-cis-retinal and intermediate states covering a wavelength range from 610 to 353 nm. These data will be useful as reference points for the calibration of more approximate schemes.Retinal is the chromophore in several photosensitive proteins where it converts light energy into structural changes (1): in the visual pigments or rhodopsins, the light-induced isomerization of 11-cis-retinal to all-trans initiates the visual cycle. In hacteriorhodopsin. all-trans-retinal is transformed by light into the 13-cis isomer, which starts the proton pumping cycle across the bacterial cell wall of Halobacterium salinarium
One particular aspect in retinal protein chemistry concerns the ultraviolet-visible spectral changes in these pigments, which serve specific needs: from ancient bacteria that use sensory rhodopsins to test the composition of light (2) to the human eye where three different rhodopsins enable the perception of colors (3). Understanding the physical origin of these changes has been a major challenge to theory ever since the original concept of the external point charge model has been introduced in the literature (4). Advances in x-ray crystallography have provided a multitude of bacteriorhodopsin structures, including intermediates of the proton pumping cycle (5) and have culminated recently in the threedimensional structure of bovine rhodopsin (6) and its first photointermediate, bathorhodopsin (7). These structures, which reveal the geometry of the retinal chromophore and its environment in atomic detail, have been instrumental for theoretical studies of retinal protein spectral shuts using diverse quantum-mechanical schemes (8-13). The dilemma that these studies face is exemplified by the fact that two of them arrive at very reasonable values for the theoretically calculated ahsorhance of rhodopsin, yet their results for the simple 11-cis-retinal protonated Schilf base (pSb). which forms the basis for the ensuing quantum mechanical and molecular mechanical (QM/MM) calculations, differ by 0.56 eV or 176 nm.
Recently the gas phase absorption spectra of several retinal Schiff bases in different protonation states have been determined (14.15) and found to peak at 610/620 nm (transpSb in Scheme 1 ). 487 nm (trans-SbN^sup +^), and 610 nm (cis-pSb). These data define much needed reference points for the calculation of retinal protein spectra, both for the protonated chromophores in vacuo and for the effect of a positive charge in a defined relative orientation to the chromophore. To cover the short-wavelength region of retinal Schiff base spectra, we also include the neutral species trans-Sb whose absorbance in the nonpolar solvent 3-methylpentane peaks at 353 nm (16). In the following, we show that CASPT2 theory at a very high level of sophistication is able to quantitatively reproduce these data.
In view of the huge computational requirements, the /(-butyl group in Scheme 1 was reduced to methyl (the solvent spectra of the two pSbs are essentially identical) (17) and N(CH^sub 3^)^sub 3^^sup +^ to NH^sub 3^^sup +^. Geometry optimization at the CASPT2 level for systems of this size is still prohibitive in computer resources. We therefore resorted to MP2 and its analytical gradients, which allow for an efficient geometry search with a correlated wave function. Starting with the DFT-optimized structures (18). the chromophores were reoptimized with MP2 using a 6-31G** basis set (19).
All four chromophores exhibit strong bond alternation (Fig. 1), which is. however, significantly reduced between C9 and N16 in the three positively charged systems. A further reduction is observed in trans- and cis-pSb, where the positive charge is part of the ?-system. From C6 to N16, all chromophores are essentially planar with the exception of r/.s-pSb. which is twisted by 7° and 3° about the C11=C12 and the C12-C13 bonds, respectively, and moves the C13-N16 fragment away from the bulky ?-ionone ring.
Ground and excited state energies were calculated with the CASSCF method as provided by the MOLCAS set of routines (20). Six-root state-averaged wave functions were expanded in an atomic natural orbital basis set (21) with the contraction C,N[4s3p1d)/H[2s]. The active space was (12,12), i.e.. all pseudo ?-clectrons and valence pscudo ?-orbitals were considered. Second-order corrections to the CASSCF energies were calculated with CASPT2. All core orbitals were kept frozen during the calculations. To avoid the effect of intruder states, the level shift was set uniformly to 0.3 au. These parameters are identical to the ones we used in recent studies on retinal model
Microspectroscopy of the Photosynthetic Compartment of Algae
We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids. Comparative analysis of absorption spectra highlighted the evolutionary grouping of the algae into three main lineages in accordance with the most recent endosymbiotic theories.According to the most recent theories different evolutionary lineages can be recognized within the algal world (1,2). Three major eukaryotic photosynthetic groups have descended from a common prokaryotic ancestor through an endosymbiotic event. The result is a set of nested cellular compartments one inside the other and information about the evolutionary history of the organism can he gleaned from the study of the membranes surrounding these compartments, the genes that they express and their function. The three lineages of primary plastids were found in the Glaucophyta, in the green algae and plants and in the red algae. The other algal groups have acquired their plastids via secondary (or tertiary) endosymbiosis, in which a eukaryote already equipped with plastids was preyed upon by a second eukaryotic cell. An endosymbiotic process produced nested photosynthetic compartments one inside the other, which can give information about the evolutionary history of the algae containing them (3,4).
9-cis Retinal Increased in Retina of RPE65 Knockout Mice with Decrease in Coat Pigmentation[dagger]
The protein RPE65 is essential for the generation of the native chromophore, 11-cis retinal, of visual pigments. However, the Rpe65 knockout (Rpe65^sup -/-^) mouse shows a minimal visual response due to the presence of a pigment, isorhodopsin, formed with 9-cis retinal. Isorhodopsin accumulates linearly with prolonged dark-rearing of the animals. The majority of Rpe65^sup -/-^ mice have an agouti coat color. A tan coat color subset of Rpe65^sup -/-^ mice was found to have an enhanced visual response as measured by electroretinograms. The enhanced response was found to be due to increased levels of 9-cis retinal and isorhodopsin pigment levels. Animals of both coat colors reared in cyclic light have minimal levels of regenerated pigment and show photoreceptor degeneration. On dark-rearing, pigment accumulates and photoreceptor degeneration is decreased. In the tan Rpe65^sup -/-^ mice, the level of photoreceptor degeneration is less than in the agouti animals, which have an increased pigment and decreased free opsin level. Therefore, photoreceptor damage correlates with the amount of the apoprotein present, supporting findings that the activity from unregenerated opsin can lead to photoreceptor degeneration.
The Rpe65^sup -/-^ mouse has been shown to have a minimal response to light by electroretinogram (ERG) measurements (6). In a previous study, we reported that endogenous 9-cis retinal accumulates and regenerates isorhodopsin through an Rpe65^sup -/-^ independent pathway during long term dark-rearing (7). Further, with single cell recordings we have confirmed that this response is due to the isorhodopsin pigment (8). The 9-cis retinal accumulation rate is very slow (~0.3 pmol/retina/day) in the normal agouti Rpe65^sup -/-^ mouse.
In this study, we show that a subset of Rpe65^sup -/-^ mice with a tan coat color exhibit enhanced ERG responses compared with usual agouti coat color Rpe65^sup -/-^ mice. The enhanced response is found to be due to increased levels of 9-cis retinal and isorhodopsin pigment levels. The increased pigment levels correlate with a decreased melanin level in the tan animals. The animals with higher pigment levels, and therefore decreased apoprotein opsin levels, showed a decrease in photoreceptor degeneration suggesting that the photoreceptor damage is resulting from basal opsin activity.
MATERIAL AND METHODS
Animals. Agouti and tan Rpe65^sup -/-^ mice were genotyped as previously described (6). Age-matched C57BL/6 and SV129 mice were purchased from Harlan Breeders (Indianapolis, IN). Animals were reared under cyclic light (12 h light/12 h dark, with the ambient light intensity at the eye level of the mice being 85 ± 18 lux) initially. Dark-rearing was initiated at 2 months-of-age. For dark rearing, the animal husbandry was performed under the dim red safety light (Kodak filter GBX-2). All experiments were performed in accordance with the policy on the Use of Animals in Neuroscience Research and were approved by the Medical University of South Carolina Animal Care and Use Committee.
Western blot analysis. Eyecups containing retinas were homogenized in 1% SDS buffer. Total proteins (60 µg) from each lysate were loaded onto 12% polyacrylamide gels and subjected to Western blot analysis using a 1:2000 dilution of primary antibodies as follows: the rabbit anti-RPE65 antibody was raised and characterized as in previous studies (9). The rabbit anti-IRBP antibody was generously provided by Barbara Wiggert, National Eye Institute. The mouse 1D4 antibody (Cellex Biosciences, Inc., Minneapolis, MN) was used for the opsin detection. The rabbit anti-RDH5 antibody was generated as previously reported (10). The mouse ?-actin antibody was purchased from Sigma. The secondary antibodies used were goat anti-rabbit IgG (1:10,000; Vector, Burlingame, CA) and horse anti-mouse IgG (1:10,000; Vector, Burlingame, CA).
ERG analysis. The experiments were performed as described previously (7,11). Briefly, animals were anesthetized by using a mixture of xylazine (20 mg/kg) and ketamine (80 mg/kg). Pupils were dilated with phenyl-ephrine hydrochloride (2.5%) and atropine sulfate (1%) separately. Contact lens electrodes (12) were placed on both eyes with the assistance of methylcellose. Full-field ERGs were recorded by using the universal testing and electrophysiologic system 2000 (UTAS E-2000, LKC Technologies, Gaithersburg, MD) in response to 10 µs single flashes of fixed intensity (2.48 photopic cd-s/m^sup 2^) under scotopic conditions. This intensity can cause saturated rod responses in C57BL/6 wild-type mice, but is not strong enough to saturate rod responses in Rpe65^sup -/-^ mice (13). This light intensity was used to minimize the bleaching of accumulated visual pigments (7). The amplitude of the a-wave was measured from the baseline to the lowest negative-going voltage. Data are presented as means ± SEM and analyzed by a one-tailed Student’s t-test, accepting a significance value of P ? 0.05
John Beech at Charlotte Jackson
Over the course of a 15-year career, John Beech has become known for wittily transforming–or appropriating the shapes of–everyday industrial objects such as car-floor mats, Dumpsters and parking-lot bumpers. This recent show comprised 11 works, mostly made in 2003 and 2004, from the four corners of his repertoire: the interactive “Rotating Paintings” made of wooden and Plexiglas disks affixed to lazy Susan hardware; the “Glue Paintings,” in which plywood structures are layered with colored glue; and two series of floor pieces, titled “Obstacles” and “Rolling Platforms.Though the artist acknowledges the influence of Donald Judd and the Minimalist esthetic, these geometric constructions are easily read as subversive offspring of Minimalism’s reductivist vocabulary. Frequently, Beech’s clever handcrafted assemblages juxtapose sleek and precisely calibrated surfaces with sections of raw plywood; sometimes he exposes the works’ bare backsides. Punctuated with spontaneous spills and splatterings of paint that often run over the edges and supports, these compositions also are a nod to Process art. For instance, Green Cube (2000), a mint-colored wall-hung box with a wide stripe of unpainted wood, incorporates metal pipes that serve as peepholes to allow the viewer to peer into its hollow interior. On the floor below Green Cube sat a mutant cube-shaped mover’s dolly in fire-engine red enamel–one of the “Rolling Platforms”–which appeared to sprout the paint-splattered casters screwed to its surfaces.
In contrast, Beech’s new additions to the “Glue Paintings” do not have the haphazard air of the earlier pieces; instead, these stark compositions are elegantly sensuous, almost despite themselves. They assume a variety of shapes, their opaque and delicately mottled monochrome surfaces achieved through the use of underpainting and meticulously brushed-on coatings of glue in which pigments have been suspended. (Previously, the “Glue Paintings” featured the “found” colors of particular brands or types of adhesive.)
Glue Painting #82, a chunky block that extends out from the wall, has smooth, faintly rippled salmon-colored surfaces. The piece’s singular lusciousness is also a product of gravity, which drew the viscous medium downward to form ridges of rounded saw-toothed peaks that subsequently hardened around the bottom edges and across the underside. These configurations, suggestive of water droplets or of frosting on a cake, curiously conjure the pastry displays found in Wayne Thiebaud’s paintings.
This emphasis on color and textural nuance in the later “Glue Paintings” obscures their humble origins while imbuing them with a meditative materiality that distinguished them from other pieces in the show. It will be interesting to see if this development in Beech’s practice signals an entirely new direction, or if it simply means that he’s about to come full circle