Quantitation of maltooligosaccharides and determination of glucoamylase activity using pulsed amperometric detection for glucose

Several aspects of the application of pulsed amperometric detection (PAD) to carbohydrate analysis are addressed. The mechanism of glucose oxidation at a gold electrode was determined by cyclic voltammetry at a rotating disc electrode in the first study. Glucose oxidation was concluded to be catalyzed by a hydrous gold oxide which was formed on the surface of the electrode in alkaline solution at potential values between -0.4 and 0.6 V versus the normal hydrogen electrode. The mechanism of glucose oxidation changed from a mass transport limited reaction with n = ca. 8 equiv mol[superscript]-1 to an electron transfer limited reaction with n = ca. 2 equiv mol[superscript]-1 as a consequence of increased glucose concentration. The change in the mechanism was concluded to result from increased competition between glucose molecules for adsorption at the catalytic sites on the gold electrode as the concentration of glucose was increased;The second study demonstrated a method for determining glucose by PAD in low capacity buffers having neutral and acidic pH values. A transient condition of alkalinity was generated within the diffusion layer of gold electrodes by stripping of surface oxide and reduction of dissolved oxygen prior to the application of the detection potential for glucose in the PAD waveform. The transient alkaline state effected the formation of the hydrous gold oxide which was necessary for the anodic detection of glucose. The method was applied to the direct determination of glucose in a continuous glucoamylase assay in the presence of the active enzyme and the starch substrate at pH 4.8. This method for glucoamylase activity was accurate, more precise, and much faster than the traditional ferricyanide assay;The final two studies demonstrated methods for determining starch by flow injection and maltooligosaccharides by chromatographic analysis with single glucose calibration curves by placing an immobilized glucoamylase reactor in series with the PAD detector cell. Starch and maltooligosaccharides were nearly quantitatively (96%) converted to glucose prior to being detected by PAD. The sensitivity of PAD for soluble starch increased 26-fold by first passing the starch through the glucoamylase reactor. The methods were used to determine total carbohydrate in beer samples and maltooligosaccharides found in corn syrup

Deafened Adults: Adjusting to a New World

The task of assisting deafened adults in adapting to the loss of receptive communication, as well as the resulting social, psychological, and employment changes presents many challenges to professionals in the field of deafness. People who became deaf after the age of 18 years have to make adjustments to offset their loss of receptive communication skills. The process of learning to accept and cope with hearing loss involves many adjustments by the deafened individuals and significant people in their lives. Rehabilitation professionals need to have an understanding of the adjustments being faced by deafened individuals and be prepared to provide them with useful information related to communication, accommodation and other services that may be needed

Development of a high performance liquid chromatographic method for the determination of the kinetic mechanism of arginine specific ADP-ribosyl transferases

A high performance liquid chromatographic method has been developed for the assay of arginine specific ADP-ribosyl transferases. ADP-ribosylation is an important posttranslational modification which consists of the transfer of an ADP-ribose group from NAD to an acceptor protein. The assay that we developed utilizes commercially available L-arginine methyl ester, LAME, as the acceptor substrate and does not require the use of radiolabels. ADP-ribosylated-LAME is separated from the reaction mixture using a C-8 reverse phase column. Prior to injection, the assay mixture is derivatized with an OPA/2-mercaptoethanol reagent. Fluorescence detection of the OPA derivatized product provides excellent sensitivity and a limit of detection of 300 femtomoles. Total analysis time is 15 minutes with ADP-ribosylated-LAME eluting at 3.9 minutes;Using this assay, we were able to determine the kinetic mechanism of two arginine specific ADP-ribosyl transferases, cholera toxin A subunit and an endogenous transferase from rabbit skeletal muscle. A random sequential mechanism was determined to be the kinetic mechanism for both of the transferases studied. Cholera toxin was reported to have K m\u27s of 5.6 mM and 39 mM for NAD and LAME, respectively. K m values of 0.56 mM and 1.2 mM were determined for NAD and LAME, respectively, using the transferase from rabbit skeletal muscle

Identifying Independent Living Skills Needs of Traditionally Underserved Persons who are Deaf

Deafness rehabilitation literature has documented the need to develop independent living skills training for traditionally underserved persons who are deaf. Prior to developing training programs, it is necessary to identify the priority needs areas of the target population. A survey was conducted with deafness rehabilitation professionals to identify the priority needs of the traditionally underserved deaf population. Respondents were asked to evaluate independent living skills areas for importance and observed competency among the target population. Based on responses to this survey, eleven priority independent living skills needs areas were identified. This information will be used as a guide to collect, review, and compile relevant curricula that can be used effectively to teach the identified priority areas

A comparative anatomical study of galls caused by the major cecidogenetic groups, with special emphasis on the nutritive tissue

The anatomies of 44 galls are discussed with special attention given to the development, longevity, and tannin content of the nutritive tissues. Within the main section of the thesis, representative galls from the major cecidogenetic groups, with the exception of bacterial and Australian scale galls, are studied. These include galls caused by fungi, nematodes, mites, moths, sawflys, scales, aphids, adelgids, tephritids, cecidomyiids, and cynipids. Three leaf mines are also described. Observations were taken from thin sections (plastic embedment) with a light microscope. The galls are arrayed along a continuum of increasing structural complexity, as judged by the degree of gall tissue differentiation. The sclerenchymatous "protective" zone and nutritive cells are used as indicators of gall complexity and of strength of the gall-former's influence over host plant tissue. Starting with the Fungal galls, then moth and sawfly galls, to the thrips, scale, mites, nematode, cecidomyiid and cynipid galls, one sees greater differentiation of gall tissues, with an increasingly distinct nutritive layer. A scierenchyma zone develops only in in midge and wasp galls. The longevity of the nutritive tissue varies from gall to gall. Generally, the nutritive tissue is maintained in an enriched state for an extended period only in galls caused by cynipids (and perhaps by nematodes). The mites and midges show enriched nutritive cells only in early gall development. No distinctive nutritive tissue occurs in the aphid galls that were studied. Generally, nutritive tissue contains less tanniferous material (as detected by the ferrous sulfate stain) than do either peripheral gall tissues or cells of the leaf. Thus, many gall-formers avoid tannins by directing the development of the cells upon which they feed. The epilogue includes a list of features shared by many galls and by gall-forming organisms. Gall-fparasites. The three appendices include 1) an anatomical study of eight galls on shrubs from the drylands of eastern Oregon (mite, cecidomyiid, tephritid, and moth galls), 2) a discussion of fossil galls and leaf mines as indicators of the age and stability of these co-evolutionary relationships. Two galled acorns from the La Brea Tar pits (Los Angeles, California) are described in this section. Lastly, 3) a discussion of economically important galls is provided. This last appendix addresses the question of why there are relatively few gall-forming insect pests, and includes a discussion of the supposed benignity of insect galls