Conformational changes induced by binding of bivalent cations to oncomodulin, a paravalbumin-like tumour protein

When Mg2+ was added to rat oncomodulin, a paravalbumin-like tumour protein, changes in the c.d. spectrum and tyrosine fluorescence intensity were observed. The addition of Ca2+ resulted in even greater changes in these spectra. The fluorescence excitation spectra of apo- and Mg-oncomodulin were superimposable, whereas that of Ca-oncomodulin was markedly different. The u.v.-absorption spectrum of the Ca2+ form also showed major differences from those of the other two forms. These observations indicate that Ca2+ induced a significant and specific conformational change in the protein that was not observed on binding Mg2+. In contrast, the conformational change induced by either Mg2+ or Ca2+ was identical in the homologous rat parvalbumin. This Ca2+-specific conformational change may be the basis for oncomodulin's Ca2+-dependent protein/protein interaction.

Application of hydrophobic chromatography to the large scale purification of Desulfovibrio desulfuricans cytochrome C3

Hydrophobic chromatography on Phenyl-Sepharose was employed for large scale purification of cytochrome c3 from Desulfovibrio desulfuricans. This chromatographic procedure minimizes operational volumes and eliminates the lengthy dialysis ordinarily used to remove large amounts of salts. Pure cytochrome c3 was obtained after one additional purification by ion-exchange chromatography.

Immobilization of isolated and cellular hydrogenase of D. desulfuricans in radiation-polymerized polyacrylamides

Purified hydrogenase from Desulfovibrio desulfuricans was immobilized either by entrapment or absorption onto porous neutral and charged acrylamide beads. Surface absorption and crosslinking on the beads resulted in a high hydrogenase activity and a good immobilization coefficient compared to the enzyme and whole cells entrapped in the same matrix. Maximum enzyme activity (citrate-phosphate buffer) was shifted to pH 6.5 upon immobilization in contrast to 6.0 for the free enzyme and the range of 6-7 for whole cells. Both the purified enzyme and whole cells were most active when held in neutral matrices. Immobilization improved the temperature stability (65 degrees C) and long term storage (4 degrees C) of the hydrogenase activity of both the purified enzyme and whole cells.

The circular dichroism of ovoverdin and other carotenoproteins from the lobster Homarus americanus

The circular dichroic (CD) spectra of the alpha-, beta'-, and gamma-crustacyanins, ovoverdin, and the yellow lobster-shell protein were measured in the region 200-750 nm, for comparison with the CD spectrum of the free carotenoid astaxanthin. The two carotenoid chromophores of ovoverdin gave a CD spectrum with a series of bands of alternating sign and ellipticities up to 1.9 X 10(5) degree X cm2 X dmol-1, comparable to the low temperature CD spectrum of astaxanthin in the UV region. The visible region of ovoverdin also contained strong CD bands where astaxanthin itself has very weak ones. The blue (640 nm) chromophore of ovoverdin gave a broad negative CD feature quite different from the blue chromophores of the three crustacyanins. The crustacyanins have a broad positive feature between 400 and 610 nm with ellipticities up to 2 X 10(5) degree X cm2 X dmol-1, followed at higher wavelengths by a negative band with an ellipticity up to 1 X 10(5) degree X cm2 X dmol-1. Gaussian curve-fitting procedures showed the positive features to consist of a minimum of two or three CD bands. In addition to the exciton bands at the main visible absorption, the yellow lobster-shell protein had a pair of CD bands of equal but opposite ellipticity associated with an absorption band between 250 and 340 nm. The UV regions of the CD spectra of the five carotenoproteins have bands from both carotenoid and protein chromophores, and possible assignments of these bands to one or the other of the two types of chromophore are proposed.

Self-association of the cardiac fatty acid binding protein. Influence on membrane-bound, fatty acid dependent enzymes

The present study on the fatty acid binding protein, purified from pig heart and studied by three independent techniques (electron spin resonance, circular dichroism, and polyacrylamide gel electrophoresis), suggests that the protein self-aggregates and exists in at least four distinct molecular species. This plurality is demonstrated by the presence of four bands after electrophoretic migration at pH 7.2 and by three transitions of molar ellipticity theta 225 that depend on protein concentration. A mathematical model is formulated to simulate the three transitions and to calculate the concentrations of the four species. The multistates manifest themselves in a complex binding capacity for fatty acid, with two sigmoidal components in the binding curve. A general equation for the curve is formulated, and the characteristic constants are evaluated by a nonlinear least-squares fit. The experimental results and their interpretation in quantitative terms lead to a theoretical evaluation of the importance of this new property of self-aggregation of the protein on the activity of membrane-bound model enzymes which are fatty acid or acyl coenzyme A dependent.

Histological appearances of the nerves of the bladder in patients with denervation of the bladder after excision of the rectum

Two groups of patients who developed denervation of the bladder after excision of the rectum for carcinoma have been studied by histological examination of bladder biopsies. The groups were compared with a group of control patients of a similar age. One group with denervation of the bladder was studied soon after (7 weeks) and the other group in the long term (10 months) after operation. Bladder biopsies were stained for acetylcholinesterase, catecholamines and connective tissue. Tissue was also processed for electron microscopy. In control patients, the ratio of cholinesterase positive nerves to the number of smooth muscle nuclei (24:100) was significantly greater than in patients with denervation of the bladder studied soon after operation (2.5: 100; P less than 0.01). Appearances consistent with degenerate nerve terminals were observed on electron microscopy in these patients. No increase in the density of adrenergic nerves was observed in either group of patients with denervation of the bladder. In the long term, a greater density of cholinergic innervation was noted compared with patients studied soon after operation (P less than 0.05). In addition, nerve terminals, similar in appearance to those of control patients, were observed on electron microscopy. The findings in patients with denervation of the bladder studied in the long term after operation are consistent with partial regeneration of autonomic nerves. They suggest that, whilst histological examination of bladder biopsies may be useful soon after excision of the rectum, they may be less sensitive in the long term.

Structural comparison of the lectin from sainfoin (Onobrychis viciifolia) with concanavalin A and other D-mannose specific lectins

The D-mannose specific lectin from sainfoin was prepared by affinity chromatography on Sephadex G-75, and its circular dichroism (CD), metal content, antigenic character, and N-terminal amino acid sequence were compared with those of four lectins from Vicieae plants and concanavalin A. The sainfoin lectin was only slightly more closely related to these other D-mannose specific lectins, than to lectins of leguminous plants in general. The CD and antigenic experiments also confirmed the close relationship of the four Vicieae lectins. The N-terminal sequence showed sainfoin has two isolectins, differing in sequence at residue four. The sequence was homologous to N-terminal sequences of several other lectins; hence, despite some structural and specificity similarities, the sainfoin lectin does not show the circular permutation of sequence unique to concanavalin A. This region also contained the sole cysteine residue, at position 33. The carbohydrate-binding properties of the sainfoin lectin were studied by gradient affinity chromatography. Its apparent Ka for methyl alpha-D-glucoside was approximately 10(3) M-1, close to the Ka of the pea lectin. However, in the relative binding behaviour of methyl alpha-D-mannoside, maltose, and methyl alpha-D-glucoside, it resembled concanavalin A more than the pea lectin.

Biofeedback-induced relaxation training as an alternative for the elementary school learning-disabled child

This study examined the effects of biofeedback-induced relaxation training on attention to task, impulsivity, and locus of control among 32 learning-disabled children between the ages of 8 and 11 years. Attention to task and impulsivity were measured by the Matching Familiar Figures Test and locus of control was measured by the Nowicki-Strickland Scale. Participants were randomly assigned to experimental (N = 16) and control (N = 16) groups. The study spanned a total of 8 weeks, with the experimental treatment consisting of three sessions spaced approximately 2 weeks apart. The treatment included EMG biofeedback training used with relaxation tapes. Univariate F values and discriminant analysis procedures revealed that the attention to task and impulsivity measures proved to be valid discriminators, respectively beyond the .01 and .05 levels of significance. Experimental group subjects had significantly fewer number of errors on the attention to task measure and significantly lower impulsivity scores. It was concluded that the biofeedback-induced relaxation training affords promise in assisting learning-disabled children in reaching their education potentials. It was recommended that future research examine the long-term efficacy and the transfer to school-related tasks of this intervention.

Secondary structural properties of the oligomeric forms of mouse IgA and the unusual effect of guanidine hydrochloride

The circular dichroism spectra of the monomer, dimer and tetramer forms of MOPC 167 mouse IgA are reported. The spectra were very similar in the aromatic region (250-310 nm) but the intensity of the negative band at 217 nm, arising from the peptide backbone, was higher in the dimer and tetramer (-4600 degree cm2 dmol-1) than in the monomer (-3400 degree cm2 dmol-1). When monomer and dimer IgA were exposed to concentrations of guanidine hydrochloride around 1.3 m, the 217 nm band increased in intensity, twofold in the case of the monomer, and solutions of the dimer became turbid, indicating aggregation of the proteins and formation of a cross-beta-structure. At concentrations of guanidine hydrochloride of above 2.3 M both proteins were similarly denatured, indicating that dimerization through J chain does not alter the stability of IgA. The aggregating effect of guanidine hydrochloride did not occur with samples of human IgA1 and IgA2 and may be related to the unusual CH1 domain of mouse IgA.

Unusual emission properties of the tryptophans at the surface of short ragweed allergen Ra5

The fluorescence and low-temperature phosphorescence of short ragweed pollen allergen Ra5 have been examined. Both the fluorescence of Ra5 in aqueous solution at room temperature and the phosphorescence of Ra5 in rigid glycol-water solvents at low temperature result entirely from the tryptophan residues in the molecule. The heterogeneity in the low-temperature phosphorescence spectra indicates that the two tryptophans in Ra5 are located in distinct environments and can be studied independently. The fluorescence wave-length maximum and large solvent-relaxation shift in the fluorescence of the allergen in 1:1 ethylene glycol-water reveal that at least one of the residues is exposed to the polar solvent. Studies of the iodide and cesium ion quenching of the fluorescence of Ra5 are consistent with this assignment but suggest that one of the tryptophans may be shielded by a negative charge in the protein. Phosphorescence data obtained in the presence of iodide and with increasing temperature confirm that both aromatic residues are readily subject to perturbation but identify the more susceptible one with one of the two spectral components that manifest themselves in the phosphorescence of Ra5. The phosphorescence wavelength maxima and the triplet-state lifetimes of the distinct tryptophans reveal that both residues lie in unusual local environment at the protein surface. While one aromatic side chain appears to be stabilized by an intramolecular interaction with a polar function, the other is perturbed quite possibly through an interaction with a disulfide linkage in the molecule.

The Baylor Video Acuity Tester

A device has been developed that offers many advantages not available with traditional visual acuity testing methods. The Baylor Video Acuity Tester (BVAT) produces randomized targets, size selectable at electronic speeds for testing even in normal ambient room light. Comparisons of the BVAT with the Project-O-Chart (American Optical Corp, Southbridge, Mass) on 60 subjects yield correlations of .93 and .95. A test-retest correlation of the BVAT of .88 was found.

Use of insecticide-impregnated ear tags for the control of face flies and horn-flies on pastured cattle

Three studies were conducted to evaluate the effectiveness of insecticide-impregnated ear tags in controlling face flies, Musca autumnalis DeGeer, and horn flies, Haematobia irritans (Linn.), on pastured beef cattle. In one 16-week trial, polyvinyl chloride (PVC) ear tags treated with stirofos (Rabon) insecticide reduced horn fly numbers by 79% (P less than .05) and face fly numbers by 30% (P less than .05). Coumaphos (Co-Ral) insecticide dust bags used in a separate herd produced an 86% (P less than .05) reduction in horn flies and an 18% (P less than .05) reduction in face flies. In the second study, 5 and 10% permethrin (Atroban), PVC-treated ear tags in a one-piece design were tested. In this 11 week trial, horn fly control averaged 95% (P less than .05) with the 10% tag and 77% (P less than .05) with the 5% tag. Face fly control averaged 49% (P less than .05) for 8 weeks with the 10% permethrin tag. No significant face fly control was achieved with the 5% permethrin tag. In a herd treated with coumaphos dust bags, horn fly control averaged 93% (P less than .05) and face fly control averaged 34% (P less than .05). The third study tested 5 and 10% permethrin, PVC-treated ear tags in a two-piece design and two-piece 5% permethrin-treated ear tags in a polyurethane matrix. Fourteen-week horn fly control averaged 88% (P less than .05) with the 10% PVC-treated tag, 83% (P less than .05) with the 5% PVC-treated tag, 71% (P less than .05) with the 5% polyurethane-treated tag and 74% (P less than .05) with coumaphos dust bags. Face fly control averaged less than 50% (P greater than .05) throughout the trial with all treatments.

Self-instruction in dental education: 1960-1980

An extensive, critical review of the dental education literature of the last two decades, related to self-instruction, reveals that this method is capable of significantly increasing cognitive knowledge in a shorter period of time and with increased student satisfaction, compared to conventional instructional methods. Suggestions for more detailed investigation of self-instructional techniques, and the need to develop a more integrated curriculum using self-instructional materials, small group interaction, and formal lectures are presented.

Evaluation of CGA 72662 as a topical spray and feed additive for controlling house flies breeding in chicken manure

The insect growth regulator, CGA 72662 (N-cyclopropyl-1,3,5-triazine-2,4,6-triamine), was tested both as a topical spray and feed additive for controlling the house fly (Musca domestica L.) breeding in chicken manure. Dosage concentrations of .025%, .05%, and .1% were sprayed on sections of manure surface in a shallow pit egg layer operation at rates of 1.9 and 3.8 liters/10.2m2. AT 17 days posttreatment each concentration at both rats, except .025% at 1.9 liters/10.2m2, provided at least a 70% reduction of native house flies and 100% inhibition of laboratory reared house flies. CGA 72662 fed to both hens and broilers at rates of 1.5 ppm and 5 ppm provided up to 100% mortality of house flies 1 day after birds were started on treated feed to 1 day after treated feed was removed.