New developments in the delivery of ganciclovir for cytomegalovirus (CMV retinitis).
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Administration, Oral↗
Biomedical subjects
J Woodward
Publications and source records attributed to J Woodward.
CTLA4Ig prolongs allograft survival while suppressing cell-mediated immunity.
T cell activation is the result of antigen-specific interactions with the TCR/CD3 complex and costimulation via other T cell surface receptors. Prevention of costimulation can result in clonal anergy. CTLA4Ig is a fusion protein that binds with high-affinity to the B7/BB1 ligand and blocks the interaction of this ligand with CD28 and CTLA4. We explored the immunosuppressive effects of CTLA4Ig in a murine nonvascularized heterotopic cardiac transplant model and in a model of cell mediated immunity. CTLA4Ig administered in vivo for two days at the time of transplantation resulted in significant prolongation of allograft survival (55 +/- 2.0 vs. 12.2 +/- 0.5 days for control, P < 0.03). Administration at later times or to previously primed animals produced no prolongation of graft survival. CTLA4Ig administered during in vivo immunization to the hapten TNP suppressed the contact sensitivity response and inhibited the subsequent in vitro generation of secondary TNP-specific CTL. CTLA4Ig administered in vivo had no effect on subsequent primary alloantigen-specific CTL or MLR responses--however, when added to culture the fusion protein inhibited the MLR response by 80%, but not the alloantigen-specific CTL response. CTLA4Ig inhibited CD4+ and CD8+ proliferative and cytokine responses to alloantigen. Flow cytometry showed no changes in distribution of subpopulations of T cells. These results confirm the immunosuppressive activity of CTLA4Ig in vivo in an allograft model and show that both CD4+ and CD8+ T cells are suppressed by CTLA4Ig. The most efficacious time of administration is during priming of the immune response at the time of antigen presentation.
Abatacept↗
Veratryl alcohol oxidase activity of a chemically modified cellulase protein.
A cellulase, cellobiohydrolase I (CBH I) from Trichoderma reesei was chemically modified by covalent attachment of pentaammine ruthenium (III) without loss in hydrolytic activity. Data suggest that such a modification endowed CBH I with oxidoreductase activity. The modified enzyme was able to carry out hydrogen peroxide-dependent oxidation of veratryl alcohol, a substrate for lignin peroxidase, at a rate of 0.148 mumol substrate oxidized min-1 mumol-1 enzyme. The effects of pH, temperature, and substrate concentration on the oxidation reaction were examined. The optimal temperature was determined to be 45 degrees C, and the optimal pH was 4.3. The Km and Vmax for veratryl alcohol were determined to be 3.519 mM and 52.27 microM min-1, respectively. Tartrate at concentrations as low as 0.10 mM was found to inhibit the reaction.
Alcohol Oxidoreductases↗
Anti-CD48 (murine CD2 ligand) mAbs suppress cell mediated immunity in vivo.
With the identification of murine CD48 as a homolog of the human CD2 ligand LFA-3 (CD58) and as a ligand itself for murine CD2, the anti-murine CD48 mAb HM48-1 was administered intravenously to investigate the role of CD48 in cell mediated immunity in vivo. Anti-CD48 mAb diminished the contact sensitivity response to the hapten trinitrophenol (TNP). mAb also inhibited in vivo priming for the subsequent generation of secondary, TNP-specific, cytotoxic T lymphocytes (CTL) in vitro. The inhibitory effect was most effective in the afferent or inductive phase of immunity for CTL, while anti-CD48 mAb was most inhibitory for the efferent or elicitative phase of contact sensitivity. Addition of anti-CD48 mAb directly to secondary CTL cultures also completely inhibited CTL generation, while addition to the lytic assay showed only minimal inhibition of CTL activity. Combining cells from mAb treated and untreated animals showed no evidence for suppressor cells. Further experiments revealed that mAb administered in vivo, as well as to culture, inhibited development of primary, alloantigen-specific CTL in vitro. Mixed lymphocyte reaction and phytohemagglutinin proliferation were partially suppressed by mAb administered in vivo or in vitro, whereas other mitogenic responses remained unaffected. Flow cytometric analysis revealed a moderate down modulation of CD48, CD3 and CD8 after treatment with anti-CD48. However, this did not represent T cell depletion since CD2, Thy-1.2 and Ig expression did not change. These results support a major unrecognized role for CD48 in diverse aspects of cell mediated immunity, affecting both CD4+ and CD8+ effector T cell function.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Evaluation and comparison of histopathologic grading systems of epithelial carcinoma of the uterine cervix: Gynecologic Oncology Group studies.
The subjects of this study are 445 patients with advanced cervical cancer treated by standardized radiation therapy. Upon entry into one of two Gynecologic Oncology Group (GOG) protocols, original pathologic diagnoses and histologic tumor descriptions for each patient were compared with separate evaluations made by a consensus opinion of two GOG pathologists. A review diagnosis using grade, cell type, and the Stendahl scoring system was then made by the first author (R.J.S.) without knowledge of the prior diagnoses. Of the original pathologists' diagnoses, 21% did not include grade or cell type. There was little agreement among the different pathologists as to the use of either specific grade or cell type. Histologic grade, irrespective of the pathologists making the diagnosis, had no correlation to prognosis. The Reagan and Wentz large-cell keratinizing (LCK) cell type, when applied by the author to tumors with any form of squamous keratinization present, identified a group of patients with a poorer prognosis, although not independently of other prognostic factors. The Stendahl scoring system identified a number of patients with both a poorer and better prognosis. This was statistically significant and independent of other risk factors. A major limitation, however, was the number of patients evaluable because of inadequate biopsy material in 23.6% of the study group.
Adult↗
Silicone and blindness: computed tomography imaging.
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Adult↗
Papain digestion of crude Trichoderma reesei cellulase: purification and properties of cellobiohydrolase I and II core proteins.
The major cellulase components produced by Trichoderma reesei are composed of distinct catalytic and cellulose-binding domains. A simple two-step procedure is described for the purification of the catalytic domains, also termed core proteins (cp), of the major components, cellobiohydrolase (CBH) I and II. The novel aspect of this procedure is that native CBH I and II do not have to be purified initially. Papain digestion of a commercial T. reesei cellulase preparation followed by gel filtration on a Superdex 75 column resulted in the separation of fractions containing CBH I cp and CBH II cp; chromatofocusing purified the latter to homogeneity. N-terminal protein sequencing of CBH II cp provided good evidence for its identity. A comparison of the catalytic activity and cellulose-binding ability of these cp was made. A major difference between them was that CBH II cp bound to microcrystalline cellulose, unlike CBH I cp. CBH I cp readily hydrolysed the bond between the aglycone and cellobiose in p-nitrophenyl cellobioside unlike the CBH II cp preparation. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyse barley beta-glucan. It was also shown that incubation of cellulose fibres with native CBH I, CBH I cp or CBH II cp resulted in a smoothing of the fibre surface.
Adsorption↗
Attachments of pentaammineruthenium(III) to Trichoderma reesei cellobiohydrolase I increases its catalytic activity.
Pentaammineurthenium(III) was covalently attached to cellobiohydrolase I (CBH I, EC 3.2.1.91), the major component of Trichoderma reesei cellulase, resulting in 0.7 mol ruthenium/mol CBH I and an electrode potential of +95 mV. Fractionation of modified CBH I by chromatofocusing resulted in the separation of fractions with a 1.4- to 3.2-fold increase in specific activity toward p-nitrophenylcellobioside, depending on the assay conditions, over that of native enzyme. The extent of the hydrolysis of insoluble cellulosic substrates (Avicel and newsprint) to glucose by modified CBH I was also greater than that observed by the native enzyme.
Cellulose 1,4-beta-Cellobiosidase↗
Comparison of Ellman's reagent with N-(1-pyrenyl)maleimide for the determination of free sulfhydryl groups in reduced cellobiohydrolase I from Trichoderma reesei.
The enzyme cellobiohydrolase I (CBH I) from Trichoderma reesei was treated with 5 mM dithiothreitol at different pH values in order to reduce some or all of its 12 disulfide bridges. A discrepancy was found in the number of free sulfhydryl (SH) groups generated upon the reduction of CBH I when they were measured using N-(1-pyrenyl)maleimide (PM) or Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid). For example, the number of SH mol generated/mol CBH I at pH 8.5 was determined to be 16 and < 1 when measured using PM or Ellman's reagent, respectively. The low value obtained with Ellman's reagent may be due to the electrostatic repulsion between the carboxylic acid groups in CBH I and those in Ellman's reagent. The fluorimetric assay used for determining SH molecules in reduced CBH I, based on their reaction with PM, is described.
Cellulose 1,4-beta-Cellobiosidase↗
Correlates of loneliness among midwestern adolescents.
The extent of loneliness among midwestern adolescents was investigated in relation to depression, self-esteem, family strengths, parent-adolescent communication, age, and gender. The study sample consisted of 156 adolescents, ranging in age from 11 to 18 years, who were attending public schools in four midwestern communities. It was found that the subjects had high loneliness scores, and that older adolescents were lonelier than younger adolescents. There was a significant relationship between loneliness and depression. Loneliness was negatively related to self-esteem, family strengths, and mother-adolescent communication. The implications of these results for delineating the underlying dimensions of loneliness in adolescents are discussed.
Adolescent↗
Procedural knowledge in mathematics: the role of the curriculum.
Over the last few years, the information processing model of cognition has become increasingly prominent in the field. With this model, and other related research in cognitive science, there is a greater appreciation for the role of instruction in learning theory. One of the model's central tenets is that, as learners become more competent, they move from declarative to procedural states of knowledge. Researchers have concerned themselves with the efficiency of this transition, as well as with any systematic misconceptions that develop along the way. A carefully developed curriculum addresses both of these concerns. This article will focus on three principles of curriculum development: the nature of examples, explicitness, and parsimony. Recently conducted research that supports these principles will also be discussed. It is suggested that special educators strongly consider these principles when selecting or developing curricular material for students with learning disabilities.
Child↗
Science instruction at the secondary level: implications for students with learning disabilities.
Designing appropriate content area instruction for secondary students with learning disabilities is a challenging endeavor. Even if these students are mainstreamed into algebra, history, or science classes, special educators are likely to expect only a minimal grasp of the material. To go beyond this, to teach higher order thinking through these subjects, would be regarded by most practitioners as too labor-intensive. The authors of this article argue that, through a comprehensive revision of traditional materials, secondary students with learning disabilities can learn content area subjects--earth science and introductory chemistry, particularly--in an integrated manner. These students can achieve a firm understanding of the subject, as well as learn how to solve complex, domain-specific problems. For this kind of integrated instruction to be feasible, the curriculum must be designed and field-tested by professional curriculum developers.
Adolescent↗
The competitive inhibition of Trichoderma reesei C30 cellobiohydrolase I by guanidine hydrochloride.
The p-nitrophenylcellobiosidase (PNPCase) activity of Trichoderma reesei cellobiohydrolase I (CBH I) was competitively inhibited by concentrations of guanidine hydrochloride (Gdn HCl) that did not affect the tryptophan fluorescence of this enzyme. The Km of CBH I, 3.6 mM, was increased to 45.4 mM in the presence of 0.14 M Gdn HCl, the concentration that was required to inhibit the enzyme by 50%. A similar concentration of lithium chloride and urea had little effect on the PNPCase activity of CBH I. Maximal inhibition was pH dependent, occurring in the range of pH 4.0 to 5.0, which is in the range for maximal activity. Analysis of the inhibition data indicated that 1.2 molecules of Gdn HCl combined reversibly with 1 molecule of CBH I. Other hydrolases and proteases were also inhibited by Gdn HCl. It is suggested that the inhibition of CBH I by Gdn HCl occurs as a result of the interaction between the positively charged guanidinium group of Gdn HCl and the carboxylate group of glutamic acid 126, postulated to be in the catalytic center of this enzyme.
Binding Sites↗
Comparison of the hydrolytic activity and fluorescence of native, guanidine hydrochloride-treated and renatured cellobiohydrolase I from Trichoderma reesei.
Guanidine hydrochloride (GdnHCl) is an effective agent for the elution of cellulase protein from unhydrolyzed cellulosic residues, but once eluted the enzyme is inactive. The studies described in this paper examine the effect of GdnHCl on the hydrolytic activity and tryptophan fluorescence of cellobiohydrolase I (CBH I) from Trichoderma reesei. CBH I was found to be completely inactivated by 0.25 M GdnHCl, but higher concentrations of GdnHCl were required to partially unfold this enzyme, as determined from the measurement of a decrease in its tryptophan fluorescence. Binding of CBH I to microcrystalline cellulose was prevented by 4 M GdnHCl, suggesting that a conformational change of CBH I resulted in the loss of substrate binding. Removal of the denaturant from CBH I by dialysis or gel filtration allowed the kinetics of the reactivation of CBH I, after 4 M GdnHCl treatment, to be studied. The fluorescence and specific hydrolytic activity of native and renatured CBH I were comparable. It is concluded, therefore, that GdnHCl may be used to elute cellulase components, such as CBH I, adsorbed on undigested cellulosic substrates since this component can easily be renatured and subsequently reused.
Cellulose↗
Cigarettes and alcohol as independent risk factors for colonic adenomas.
Healthy adults completed smoking and alcohol consumption questionnaires before colonoscopies, which were performed because of occult blood in the stool or prior barium enema suggesting polyps. Subjects with adenomas at colonoscopy (n = 102) were compared with colonoscopy-negative controls (n = 89). In univariate analyses, age (p less than 0.05), male sex (p less than 0.005), cumulative smoking (p less than 0.0001), and cumulative beer consumption (p less than 0.005) were associated with adenomas. The association of smoking with adenomas was stronger in younger subjects. The association of beer with adenomas was stronger in older subjects. Logistic regression confirmed statistically significant associations of smoking (odds ratio for greater than 40 pack-years = 3.31; confidence intervals 1.41, 7.81) and beer consumption (odds ratio for greater than 40 beer-years = 2.64; confidence intervals 1.10, 6.32) with adenomas. These results suggest that smoking and beer consumption are independent risk factors for colonic adenomas.
Adenoma↗
Effect of the 21-aminosteroid U-74006F on cerebral vasospasm following subarachnoid hemorrhage.
The purpose of this study was to use a new 21-aminosteroid (U-74006F) with in vitro antioxidant and antilipolytic properties as a pharmacological probe to assess the role of lipid hydrolysis and peroxidation in a rabbit model of subarachnoid hemorrhage (SAH)-induced vasospasm. Cerebral angiograms were performed on 15 rabbits. Eighteen hours later, 1 cc/kg of autologous blood was infused into the cisterna magna of all 15 animals. Six rabbits received no treatment, six received U-74006F starting 30 minutes after SAH, and three rabbits received the vehicle for U-74006F starting 30 minutes after SAH. At 72 hours post-SAH, a second angiogram was obtained. Digital subtraction angiographic techniques were used to measure the diameter of and contrast material flow through the basilar artery. At 72 hours post-SAH, vasospasm was evident in all untreated and vehicle-treated rabbits. The diameter of and the flow through the basilar artery were significantly reduced 42.3% +/- 6.6% and 46.8% +/- 5.8%, respectively, below pre-SAH levels (means +/- standard error of the means). Treatment with U-74006F eliminated the SAH-induced vasospasm; in treated animals, both the flow through and the diameter of the basilar arteries were at pre-SAH levels. These findings indicate that: 1) membrane lipid changes (that is, hydrolysis with eicosanoid production and/or peroxidation) contribute to the chronic vasospasm resulting from SAH, and 2) U-74006F prevents the SAH-induced chronic vasospasm in this model by limiting these pathological membrane events.
Animals↗
The Leo Award 1988. AIDS and a GP: an apocryphal tale.
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Acquired Immunodeficiency Syndrome↗
Hydrolysis of cellulose by a mixture of Trichoderma reesei cellobiohydrolase and Aspergillus niger endoglucanase.
Two endoglucanase-containing fractions were separated from Aspergillus niger cellulase by gel filtration and fast protein liquid chromatofocusing (FPLC). They possessed no ability to bind to or hydrolyze insoluble microcrystalline cellulose (Avicel) but were active toward soluble carboxymethylcellulose. No synergism was observed between Trichoderma reesei cellobiohydrolase I and either endoglucanase from A. niger. These findings may indicate that the role of the endoglucanase component of cellulase in insoluble microcrystalline cellulose hydrolysis is dependent upon its ability to be adsorbed upon the substrate.
Aspergillus niger↗