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PubMed1975

Comparative biophysical studies of hepatitis B antigen, subtypes adw and ayw.

Comparative biophysical and biochemical analyses were performed on purified preparations of hepatitis B antigen (HBs Ag) subtypes adw and ayw, including isoelectric pH evaluations, analysis of the different morphological forms, molecular weight determinations, and analysis of the polypeptides by polyacrylamide gel electrophoresis, Both HBs Ag-positive plasma and purified HBs Ag were analyzed by electrofocusing in a sucrose ampholyte gradient. Four distinct populations of HBs Ag with a pH range of 4.5 plus or minus 0.1 to 5.4 plus or minus 0.1 for unfractionated plasma samples and 3.9 plus or minus 0.05 to 4.9 plus or minus 0.05 for purified samples were detected in both adw and ayw preparations. Electron microscopic studies of each population of purified HBs Ag revealed 19- to 27-nm spheres in each fraction. Purified material labeled with 125I by the chloramine-T method behaved as one major population with an isoelectric pH value of 3.9 plus or minus 0.1. Purified adw preparations revealed a major population with a molecular weight of 3.7 times 10-6 and a second one of 4.6 times 10-6. Purified preparations of ayw contained one population with a molecular weight of 4.6 times 10-6. Polyacrylamide gel electrophoretic analysis of purified HBs Ag revealed nine polypeptides for ayw and seven for adw particles. These studies indicate that purified preparations of HBs Ag are heterogeneous and that distinct differences can be detected between the two subtypes.

Centrifugation, Density Gradient↗
PubMed1976

Comparison of biophysical and morphological properties of occluded and extracellular nonoccluded baculovirus from in vivo and in vitro host systems.

Electron microscopic examination and buoyant density profiles of nonoccluded Rachiplusia ou and Autographa californica nuclear polyhedrosis viruses purified from both infectious insect hemolymph and cell culture medium revealed that the viruses are enveloped, single nucleocapsids. The envelopes exhibited variation in the amount and degree of fit with regard to the nucleocapsids. This was determined by: (i) electron microscopic observations of virus budding from the surface of infected cells; (ii) electron microscopic observations of negatively stained preparations of pelleted, highly purified, nonoccluded enveloped particles; and (iii) the resolution and density distributions of nonoccluded virus in sucrose gradients after centrifugation to equilibrium; all were compared with virus extracted from polyhedra. Peplomers, ovserved on the surface of enveloped nucleocapsids of nonoccluded virus, are not associated with polyhedra-derived virus. Density gradient analysis indicated that virus from insect hemolymph and culture medium exhibited similar densities of approximately 1.17 to 1.18 g/ml. This is significantly different from the buoyant density of an alkali-liberated, enveloped single nucleocapsid (1.20 g/ml). Results of this study show that the nonoccluded forms of two nuclear polyhedrosis viruses from two different sources, hemolymph and cell culture, are similar with regard to several morphological and biophysical characteristics but are quite different from the alkali-liberated, polyhedra-derived form of the virus.

Animals↗
PubMed1979

Biophysical and biochemical characterization of five animal viruses with bisegmented double-stranded RNA genomes.

Infectious pancreatic necrosis virus of fish, infectious bursal disease virus of chickens, Tellina virus and oyster virus of bivalve molluscs, and drosophila X virus of Drosophila melanogaster are naked icosahedral viruses with an electron microscopic diameter of 58 to 60 nm. The genome of each of these viruses consists of two segments of double-stranded RNA (molecular weight range between 2.6 x 10(6) and 2.2 x 10(6), and the virion, capsid proteins fall into three size class categories (large, medium, and small; ranging from 100,000 to 27,000) as determined by polyacrylamide slab gel electrophoresis. The hydrodynamic properties of the five viruses are similar as determined by analytical ultracentrifugation and laser quasi-elastic, light-scattering spectroscopy. The calculated particle weights range between 55 x 10(6) and 81 x 10(6). Tryptic peptide comparisons of 125I-labeled virion proteins showed that five viruses are different from each other, although there was considerable overlap in the peptide maps of the three aquatic viruses, indicting a degree of relatedness. Cross-neutralization tests indicated that drosophila X, infectious pancreatic necrosis, and infectious bursal disease viruses were different from each other and from oyster and Tellina viruses. The same test showed oyster and Tellina viruses to be related. The biochemical and biophysical properties of the five viruses cannt be included in the family Reoviridae or in any of the present virus genera.

Animals↗
PubMed1979

Biophysical mechanisms contributing to inking behavior in Aplysia.

1. The release of ink from the ink gland of Aplysia californica in response to noxious stimuli is mediated by three electrically coupled motor neurons, L14A, L14B, L14C, whose cell bodies are located in the abdominal ganglion. The initial synaptic input to the ink motor neurons is relatively ineffective in firing the cells. As a result, a pause of 1--3 s often occurs before the cells attain their maximum firing frequency and cause the release of ink. Using current and voltage-clamp techniques we have analyzed the mechanisms underlying the firing pattern of these cells. 2. The presence of a fast transient K+ current appears to play an important role in mediating the firing pattern of the ink motor neurons. Their high resting potential (-75 mV) ensures that the steady-state level of inactivation of the conductance channels for the fast K+ current will normally be low. Thus a train of EPSPs or a depolarizing current pulse can activate this current maximally, thereby reducing the initial effectiveness of the excitatory input. 3. In addition to the fast transient K+ current, four other currents were identified: 1) a fast transient tetrodotoxin-sensitive inward current, presumed to be carried by Na+; 2) a slower tetrodotoxin-insensitive inward current, presumed to be carried by Ca2+; 3) a slow transient outward tetraethylammonium- (TEA) sensitive current; and 4) a very slow TEA-insensitive outward current. 4. A decreased conductance EPSP, which turns on over a several-second period, contributes to a late acceleration of spike discharge in the L14 cells. 5. The results suggest that a unique combination of biophysical properties of the L14 cells and the features of the synaptic input cause them to act as a low-pass filter in the reflex pathway for inking. Their high resting potential, which ensures minimal inactivation of the fast transient K+ current channel, makes these cells preferentially responsive to strong and long-lasting stimuli. The delayed recruitment of a decreased conductance EPSP augments the tendency of the L14 cells to fire in an accelerating burst pattern.

Aggression↗
PubMed1976

The DNA of Volvox carteri: a biophysical and biosynthetic characterization.

Various biophysical and biosynthetic characteristics of deoxyribonucleic acid (DNA) from Volvox carteri are examined. The DNA from three strains (HK-10,NB-7 and KA-1) is compared, and all strains are shown to contain at least two distinct DNA species which band at densities of 1.714-1.715 and 1.704-1.705 g/cm3 in neutral CsCl and correspond to nuclear and "cytoplasmic" DNA, respectively. Base compositions calculated from these densities, 55-56% G+C for nuclear DNA, and 45-46% G+C for cytoplasmic DNA, are in close agreement with % G+C values estimated from thermal denaturation data. DNA from strain KA-1 has a third component with a buoyant density of 1.693 g/cm3. DNA synthesis is analysed using radioactively labelled heterogeneously grown strains of Volvox carteri and profiles obtained following preparative CsCl density gradient centrifugation are presented. In addition, dissimilarities in patterns of DNA synthesis at various periods in the asexual life cycle are reported for synchronous cultures of strain HK-10. These differences in temporal patterns of DNA synthesis clearly indicate that while nuclear DNA is make to some degree throughout the life cycle, cytoplasmic DNA synthesis appears to occur only at discrete intervals.

Animals↗
PubMedDate not supplied

[Dynamics of matrix synthesis in molecular biophysics].

The paper deals with connections of structural-functional and dynamic approaches in the problems of molecular biophysics with reversible problems of the dynamics of matrix synthesis of biopolymers. Operator equation of dynamics describing such connections is obtained.

Biopolymers↗
PubMed1975

Swiss albino mouse brain gangliosides: biophysical studies.

The brain gangliosides mixture of Swiss albino mice were studied from a biophysical viewpoint. The value of v found was 0.577 ml/g. The isoelectric point gave a value of 1.50, which is in agreement with the presence of sialic acid groups. The isoionic point, 2.76, is close to the pKa for sialic acid. The number average molecular weight determined in the presence of ions was 229000, while in the absence of ions it was 78000, this weight suggesting a low degree of aggregation. The[eta] value of 3.56 and 4.84 in both the presence and absence of ions would indicate an asymmetrical micelle and/or more solvate than a rigid or impermeable sphere. The value of S020, w in the presence of ions was 9.19, while in their absence it was 7.65, corresponding to a lower molecular weight coincident with that found for Mn. Hydrodynamic relations permit the supposition that the brain gangliosides mixture of Swiss albino mice is not a symmetrical micelle, since the frictional and symmetry ratio found is equal to 1.29, which corresponds to an axial ratio of 6. The value of D is equal to 2.30 X 10(-7) cm2/sec; this fact is even more suggestive that we are not dealing with a symmetrical micelle. It was not possible to calculate the molecular weight using equations under the assumption that gangliosides are a spherical micelle. It was concluded that they might be a prolate ellipsoid of revolution.

Animals↗
PubMed1975

[Clinical, anatomical and biophysical data on a case of encephalopathy with aluminum deposits].

A man presented at 27 years of age, the first signs of a progressive neurological and mental deterioration which eventually lead to his death at 37, from an intercurrent pulmonary infection. He was a severe alcoholic. The pathological examination of the brain revealed patchy demyelination and deposits of crystalline material, resembling so called calcifications. The biophysical examination showed the presence in the brain and other organs, of aluminum and phosphorus in all deposits, sometimes associated with iron, sulfur and calcium. Nothing in his past history suggests any contact with aluminum. Presumably this is a case of "generalized aluminosis", with the main clinical and pathological features manifesting in the central nervous system.

Adult↗
PubMed1979

[Contribution of I. M. Sechenov to the development of respiratory physiology and biophysics].

Analysis of I. M. Sechenov's scientific heritage, of the data cited in his "Autobiographic Notes", and of his contemporaries' memoirs showed that problems of physiology and biophysics of respiration closely followed the problems of central nervous system and psychology in the scientist's creative work. The principle of resumed vacuum is shown to have major significance for extraction of the blood gases and invention of absorptiometer underlying further modifications of the model. I. M. Sechenov's studies in binding of CO2 by different blood components and saline solutions, in interrelationship of oxygen binding by erythrocytes and output of carbonic acid, in solubility of carbonic acid in water, as well as other problems studied by the eminent Russian physiologist, are reviewed.

History, 19th Century↗
PubMed1979

Histochemical and biophysical study of cuticle sclerotization in Pycnoscelus surinamensis L. (Blattaria).

The problem of melaninogenesis and quinone tanning of the cuticle was examined by histochemical and biophysical methods (electroparamagnetic resonance: EPR) on normal subjects of Pycnoscelus surinamensis and on subjects with abnormal cuticular colour. The cuticle of abnormal subjects showed a lower content of polyphenolic substances and a greater positivity for the indole group. This suggests that in these insects tanning products can be synthetized differently and not derived from tyrosine but from tryptophan as postulated by Pryor (1955). Furthermore, a higher number of unsaturated aminic groups is found in abnormal subjects. Granules present only in the cytoplasm of the epidermal cells of the abnormal newly moulted subjects may indicate that the polyphenolic compound of tanning, secreted in an inactive form as 4-0, beta-glucoside, is not freed from the beta-glucosidase and remains as such in the cytoplasm.

Animals↗
PubMed1975

Biophysical characterization of the adr subtype of hepatitis B antigen and preparation of anti-r sera in rabbits.

The biophysical properties of the adr subtype of HBSAg were determined and found to be identical to those of the adw and ayw phenotypes. These properties were used to purify the 22 nm spherical form of HBSAg/adr from the serum of a chronic antigen carrier by using zonal centrifuge techniques. The purified antigen was injected into 15 rabbits which were bled weekly to follow the development of antibodies to HBSAg by hemagglutination, and to the subtype determinants of HBSAg by counterelectrophoresis and agar gel diffusion (AGD) assays. From these data and two pilot studies to produce anti-w using an adw and an ayw antigen the relative immunogenicities of the various HBSAg determinants could be ranked as a greater than r greater than d greater than y greater than w. A selected pool of the sera from the rabbits immunized with HBSAg/adr was prepared as an interim reference reagent; when diluted 1:4 in saline and tested by AGD, it contains anti-a and anti-r without demonstrable anti-d or anti-normal human serum activity.

Animals↗
PubMed1979

Biophysical and serologic comparison of four equine adenovirus isolates.

Four equine adenovirus isolates have been characterized with regard to their biophysical and serologic properties. Electron microscopic studies demonstrated that purified virions have a typical adenovirus morphologic characteristic, with 50-nm-long fiber projections at each vertex of an 80-nm-diameter icosahedron. Extracted viral DNA was found to be a linear duplex of molecular weight 21 to 22 x 10(6). All four isolates were found to have a buoyant density in CsCl of 1.346 +/- 0.002 g/ml. Hexon structural components prepared from each isolate were shown to carry the same relative net charge, as judged from anion exchange elution profiles. Sodium dodecyl sulfate (sodium lauryl sulfate)-polyacrylamide gel electrophoresis revealed that the four isolates were composed of which the electrophoretic migration pattern was distinct from that of a human adenovirus reference. Serologic data (serum-neutralization and hemagglutination-inhibition tests) did not reveal any distinct antigenic diversity among the four isolates. On the basis of data obtained in this study, it is proposed that equine adenovirus isolates thus far available do, in fact, constitute a single serotype.

Adenoviridae↗
PubMed1979

Histochemical and biophysical study of cuticle sclerotization in Pycnoscelus surinamensis L. (Blattaria).

The problem of melaninogenesis and quinone tanning of the cuticle was examined by histochemical and biophysical methods (electroparamagnetic resonance: EPR) on normal subjects of Pycnoscelus surinamensis and on subjects with abnormal cuticular colour. The cuticle of abnormal subjects showed a lower content of polyphenolic substances and a greater positivity for the indole group. This suggests that in these insects tanning products can be synthetized differently and not derived from tyrosine but from tryptophan as postulated by Pryor (1955). Furthermore, a higher number of unsaturated aminic groups is found in abnormal subjects. Granules present only in the cytoplasm of the epidermal cells of the abnormal newly moulted subjects may indicate that the polyphenolic compound of tanning, secreted in an inactive form as 4-O, beta-glucoside, is not freed from the beta-glucosidase and remains as such in the cytoplasm.

Animals↗
PubMed1977

Morphologic, biophysical, and biochemical consequences of ligation of the common biliary duct in the dog.

Common biliary ducts of 32 adult mongrel dogs were ligated for a period of 2 days to 6 weeks. Sham-operated animals served as controls. Bile ducts were removed at sacrifice, and biophysical, morphologic, and biochemical parameters were measured. Our study shows that biliary duct ligation results in an immediate increase of intraductular pressure and is followed quickly by significant increase in the rate of collagen synthesis and the activity of prolyl hydroxylase. Histologic data show subepithelial inflammation followed by marked increases in periductular fibrosis. This fibroproliferative response is paralleled by peak levels of prolyl hydroxylase activity at 2 weeks prostligation. Paradoxically, bile ducts continuously distend throughout the ligation period despite increased fibroplasia. We present here the first topographic (SEM) study of normal and ligated common bile duct epithelium. Following 2 weeks of ligation large crater-like fenestrae are seen ductular epithelial surfaces. This is followed by focal epithelial sloughing. We speculate that the continuous distention and epithelial necrosis seen in the present study may be due to biliary stasis and/or subepithelial infiltration of bile through epithelial fenestrae. This hypothesis is supported by our studies which show that collagen extractibility is markedly increased by the addition of bile to the homogenate.

Animals↗
PubMed1976

[Iodine effects in body tissues - a survey and biophysical approach to interpretation (author's transl)].

An attempt was made to interpret the therapeutic and biological effects of iodine on the basis of currently available biophysical information. The easily facilitated electron transfer from and to the external shell of the iodine atom is considered to account, first of all, for good tissue compatibility of molecular iodine as an oxidizing antiseptic, secondly, for the role of iodine as a biocatalyzer of oxidation and reduction processes, thirdly, for the role of iodine as an agent lowering the electric resistance of membranes and, finally, for a possible intracellular release of iodine from iodine-containing hormones and amino acids, thereby affecting enzyme activities. A low electrostatic charge density of iodide and, hence, a small ionic hydration shell imply two biologically significant facts: an intensified ionic mobility and a breaking of the immediate water structure (chaotropy). These physical phenomena are thought to be well suited to explain the strong binding capacity of iodide to proteins, the loosening of electrostatic and hydrophobic bonds within the tissues and an overall increase in protein solubility.

Binding Sites↗