Lyotropic mesophase of imogolite, 2. Microscopic observation of imogolite mesophase

Imogolite, though achiral, forms cholesteric spherulites in the anisotropic phase as shown by the regular striations arranged in a swirl-like or fingerprint pattern observed through a polarizing microscope. Electron microscopy revealed the raft-like imogolite sheet floating in the anisotropic phase. The structure of the imogolite sheet was deduced from periodicities observed by an electron microscope using various imaging conditions. The origin of the twisting force to maintain the cholesteric ordering is also discussed.     

Lyotropic mesophase of imogolite, 3 observation of liquid crystal structure by scanning electron and noval polarized optical microscopy

The mesophase (lyotropic liquid crystal) of the inorganic rod-like polymer, imogolite, displays a typical fingerprint texture under a polarized optical microscope (POM), although the mesophase reveals no circular dichroism. The scanning electron microscope revealed a honeycomb structure of thin sheets having pleats in the freeze-dried sample prepared from the mesophase solution, and POM shows also a fingerprint texture from the same sample. A novel polarized optical microscopic observation procedure was introduced to eliminate the contrast variation and extinction due to the zero amplitude effect which depends on the orientational variation of anisotropic bodies with respect to a polarizer direction under the crossed Nicols. Various textures of lyotropic imogolite liquid crystals were observed with the procedure, and the results were accounted for by a honey-comb structure of curled thin sheats having pleats. The honey-comb model is consistent with the observation by scanning electron microscopy on the freeze-dried sample.     

Dilute solution properties of imogolite

Imogolite, a natural product in the clay fraction of Japanese soil, was characterized through its dilute solution properties. Various methods were employed for this characterization, including viscosity, sedimentation, static/dynamic light scattering, and small angle X-ray scattering. All these measurements have revealed consistently that imogolite is represented by a rigid thin rod within the accuracy of available theories, where its repeat unit is composed of twelve gibbsite units. Since the evaluation of the chain length from the observed quantities depends on the molecular weight distribution, its effect was also considered where M_w/M_n ≈ 1,2 was estimated from the sedimentation profile.     

^3H—毛冬青甲素在动物体内分布的研究

毛冬青甲素系毛冬青的主要活性成分，为研究其在体内的作用途径和归经理论的关系，探讨中约归经的实质，本文采用放射性核不踪技术，观察＾３Ｈ－毛冬青甲素在动物体内各主要器官组织分布的动态变化。实验结果显示，心，肺，肝组织和血液的示踪剂含量最高，大脑，睾丸，眼球组织也有相当数量地示踪剂分布，说明这些组织是该药的敏感靶器官，并可透过血脑，血睾屏障。     

Compositional heterogeneity and molecular weight distribution of copolymer systems, 2. Kinetics of free-radical grafting and heterogeneity of its product

The heterogeneity of graft copolymers was interpreted on the basis of the kinetics of free-radical grafting under the conditions in which grafting was expected to be random. Besides some well-known kinetic equations, a new equation relating the rate of graft-chain production with the initiator, monomer, and prepolymer concentrations was derived. The theory was applied to analyze Cameron's data on the benzoyl peroxide initiated styrene grafting onto polybutadiene in benzene. It was found that the theory quantitatively describes the experimental results. Also an equation relating the graft fraction with the prepolymer and monomer concentrations under the conditions in which terminations were dominated by disproportionation was proposed.     

The influence of surface chemistry on implant interface histology: a theoretical basis for implant materials selection.

A theory is proposed stating that an ideal implant material must have a dynamic surface chemistry that induces histological changes at the implant interface which would normally occur if the implant were not present. Evidence for the validity of this theory is provided with a series of bone-implant studies which result in stable interfacial osteogenesis under specific implant surface chemistry conditions. Insufficient or excess surface ion concentrations produce negative osteogenesis and fixation results. Implantation of osteogenic implants in soft tissues also produces undesirable histological responses as proposed in the theory. A variety of surface chemical analyses of the implant are reviewed which provide a scientific basis for the implant surface theory.     

Tumour necrosis factor alpha concentrations in the peritoneal fluid of infertile women with minimal or mild endometriosis are lower in patients with red lesions only than in patients without red lesions

Tumour necrosis factor alpha (TNFalpha) of peritoneal fluid is believed to have important pro-inflammatory and angiogenic activities in the complex mechanisms of development of peritoneal endometriotic lesions. We have evaluated the concentrations of TNFalpha and macrophages in peritoneal fluid of infertile women with minimal or mild endometriosis and related them to the presence of peritoneal red lesions alone (red lesions only group; n = 11) or their absence (non-red lesions group; n = 36). A group of 39 infertile normo-ovulatory patients with normal pelvic anatomy was used as controls. TNFalpha concentrations did not differ between controls and either group of patients. Patients with red lesions only had significantly lower concentrations of TNFalpha in peritoneal fluid (P < 0.05) and had a higher proportion of samples with undetectable concentrations (P < 0.05) than patients without red lesions. The significant difference in TNFalpha concentrations was present when comparing the groups of patients in the proliferative phase but not in the secretory phase. Macrophage concentrations were not different in the groups. Our findings are compatible with an impairment of macrophage function and therefore lend support to the theory that an inappropriate immunological response of the peritoneal environment to regurgitated endometrium may play a part in the initial phases of endometriotic implants.     

Branching in free radical polymerization due to chain transfer, 3. Polymerization of styrene in the presence of a tetrafunctional chain transfer agent

The effect of neopentanetetrayl tetrakis(2-mercaptoacetate) on the molecular weight of polystyrene in free radical polymerization was studied. Polymerization experiments were carried out at three different concentrations of the tetrafunctional transfer reagent and were followed to monomer conversions up to β = 25%. For comparison, runs of polymerization were made without added transfer reagent and with a monofunctional 2-mercaptoacetate, respectively. An apparent extent of branching was calculated from the molecular weights M_w obtained with the tetrafunctional and the monofunctional transfer reagent at fixed monomer conversion β and fixed concentration of reagent groups. This apparent extent of branching passes through a maximum at very small β and approaches the value 1 for large β. The decrease in the extent of branching is shown to be caused by the increasing fraction of linear polystyrene as the transfer reagent becomes exhausted. The data observed were compared with curves calculated from Cascade Theory with the known kinetic constants for polystyrene. A very good agreement between theory and experiment is observed at medium concentration of transfer groups. At smaller concentrations the increase in M_w is less than that predicted, and at large concentrations the increase in M_w is stronger than expected by theory. The deviations are attributed to negative and positive substitution effects.     

The use of spatially resolved fluorescence and reflectance to determine interface depth in layered fluorophore distributions

The possibility of using spatially resolved fluorescence and reflectance measurements to recover tissue optical properties, fluorophore concentration and the thickness of a superficial layer in a two-layer geometry was investigated. A diffusion theory model was used to fit reflectance and fluorescence data generated using Monte Carlo simulations or experimentally obtained using tissue-simulating phantoms. Initial analysis fitting diffusion theory generated data suggested that it should be possible to recover all parameters from a single set of spatially resolved fluorescence and reflectance measurements. However, when Monte Carlo or experimental data were fitted the results were less impressive. Overall, it was shown that there is a strong coupling between interface depth, fluorophore concentration and tissue absorption, especially at larger depths. The recovery of all input parameters from a single set of spatially resolved measurements was limited to interface depths less than 3 mm, which is a reasonable range for measuring fluorophore in skin. When the tissue optical properties and fluorophore concentrations were known, then the interface depth could be monitored with good accuracy in simulated serial measurements. These results may also point to deficiencies in the diffusion theory model that introduce significant errors in the fitted results.     

Osmotic Pressures for Binary Solutions of Non-electrolytes

A comprehensive new theory of osmotic pressure is mechanistically derived to be applicable to incompressible binary solutions of non-electrolytes independent of solute concentrations, membrane selectivity, solution ideality, and without recourse to adjustable parameters. The approach employed relies on Ficks diffusion laws, and introduces the concept of uncoupled aggregate diffusion. The theory is verified using direct and indirect experimental data of sucrose solutions and then compared to conventional osmotic pressure laws. Direct consequences of the new theory entail novel a priori expressions for the activity, activity coefficient, and chemical potential of solvent. Applications to drug delivery and biomolecular separation nanotechnology are discussed.     

Osmotic coefficients of aqueous polyelectrolyte solutions at low concentrations, 4. Modified cylindrical cell model and its application

A modified rodlike model of linear polyelectrolytes is described and the calculated osmotic coefficients are presented as a function of the degree of polymerization of polyions. A comparision with experimental data is included and rather good agreement with theory is found at concentrations above 5.10^?3 basemol/l. The concentration dependence of the properties of diluted polyelectrolyte solutions is discussed.     

Aspirin-like effects of selected food additives and industrial sensitizing agents

A number of food additives and industrial chemicals, responsible for inducing symptoms of intolerance in some individuals, have been studied in tests measuring platelet activation by noradrenaline. All the investigated agents inhibited platelet aggregation and this was associated with inhibition of the cyclo-oxygenase-thromboxane pathway. Suboptimal inhibitory concentrations of the agents studied had additive inhibitory effects on platelet aggregation when they were tested in pairs, or when tested with salicylate or aspirin. The results support the theory that some food additives and industrial chemicals induce intolerance because of their aspirin-like properties.     

A comparison of ion concentrations, potentials and conductances of amphibian, bovine and cephalopod lenses.

1. The concentrations of sodium, potassium and chloride in frog and bovine lenses showed a normal intracellular ion distribution with the sum of the internal cations approximately equal to the external sum. In the cephalopod lens, however, the sum inside was much lower than that outside.2. The membrane potentials of frog, Sepiola and bovine lenses were -63, -63 and -23 mV respectively. A comparison of the electrical data with the Nernst potentials predicted from ion concentration data indicated that sodium and chloride ions as well as potassium contributed to the membrane potential in frog and bovine. In contrast, the membrane and Nernst potentials for potassium were equal in Sepiola.3. Substituting potassium for sodium in the external medium depolarized lens potentials in all three species. Estimates of the relative permeabilities of sodium, potassium and chloride were obtained by fitting the Goldman-Hodgkin-Katz equation to the potential data.4. The potassium permeability was determined directly by (42)K efflux measurements and values of 2.99, 9.83 and 3.13 (x (-8) m sec(-1)) were obtained for frog, Sepiola and bovine lenses respectively.5. The effect of raising external potassium on the efflux rate constant was determined and there was reasonable agreement between experiment and theory (Kimizuka-Koketsu) in frog and bovine lenses, but the Sepiola data indicated that the potassium permeability decreased by a factor of 2.6 when the external potassium was raised from 10 to 120 mM-K+.6. The measured specific conductances, obtained using two internal micro-electrodes, were 7.7, 15.9 and 9.9 (Sm(-2)) for frog, cephalopod and bovine lenses respectively. These data compare with computed values (Kimizuka-Koketsu theory) of 7.5, 14.1 and 17.2 (Sm(-2)).7. The effect of increasing external potassium on the conductance was also tested and there was good agreement between experiment and theory (assuming constant permeabilities) only in the amphibian lens. However, when the cephalopod data were corrected assuming a 2.6-fold decrease in P(K) for a twelvefold increase in potassium, then there was excellent agreement between experiment and theory.8. The bovine measured conductances were much lower than the theoretical values throughout the range of external potassium concentrations and several explanations were proposed to account for the discrepancies.     

Dissociating the effects of nitrous oxide on brain electrical activity using fixed order time series modeling

A number of commonly used anesthetics, including nitrous oxide (N2O), are poorly detected by current electroencephalography (EEG)-based measures of anesthetic depth such as the bispectral index. Based on a previously elaborated theory of electrocortical rhythmogenesis we developed a physiologically inspired method of EEG analysis that was hypothesized to be more sensitive in detecting and characterizing N2O effect than the bispectral index, through its combined EEG estimates of cortical input and cortical state. By evaluating sevoflurane-induced loss of consciousness in the presence of low brain concentrations of N2O in 38 elective surgical patients, N2O was associated with a statistically significant reduction in the input the frontal cortex received from other cortical and subcortical areas. In contrast the bispectral index responded only to low, but not to high, concentrations of N2O.     

Changes in superoxide radical and lipid peroxide formation in the brain, heart and liver during the lifetime of the rat

The free radical theory of aging was examined by measuring the formation of superoxide radical (SOR) and the level of lipid peroxides in various tissues of the aging rat. A significant increase in SOR production was seen in mitochondria prepared from the brain and the heart as rats aged. An elevation in the level of lipid peroxidation was also found in whole tissue homogenates of the brain and the liver. Vitamin E concentrations in the blood rose rapidly in young rats and remained steady except for a non significant drop in old animals. These results suggest that age-related degeneration of various tissues in the rat may be due to a rise in free radical production in the mitochondria.     

Systemic reactive amyloidosis associated with Castleman's disease: serial changes of the concentrations of acute phase serum amyloid A and interleukin 6 in serum.

A case is reported of a 21 year old woman who suffered from Castleman's disease and systemic reactive amyloidosis. The serum concentrations of serum amyloid A (SAA) and interleukin 6 (IL-6) were extremely high and amyloid protein was immunohistochemically identified as AA. After surgical excision of a large retroperitoneal lymph node with the pathological findings of plasma cell type of Castleman's disease, both serum SAA and IL-6 declined, showing a similar pattern of reduction curves. All clinical symptoms and laboratory abnormalities greatly improved. The biochemical feature of Castleman's disease is abnormal production of IL-6 and this cytokine continuously may stimulate the synthesis of an amyloid precursor, SAA, causing systemic reactive (AA) amyloidosis. This pathogenetic theory is strongly supported by the present study.     

Stimulation of proliferation of murine lymphocytes by the calcium ionophore A 23187 in the absence of serum: the requirement for thiols

The proliferation of mouse spleen cells and T-lymphocytes, initiated by the calcium ionophore A 23187 was studied by a serum-free culture technique. In contrast to Con A, A 23187 was capable of stimulating cells only if 2-mercaptoethanol, cysteine and glutathione (reduced form), respectively, were present in the culture medium. In the absence of one of these compounds a stimulating activity of A 23187 was observed only with high concentrations of cells (i.e., 10(7)/ml). With glutathione present, the cells could be stimulated only at concentrations of A 23187 which were found to be suboptimal in cultures with 2-mercaptoethanol. Human serum, fetal calf serum and bovine serum albumin shifted the active and optimally stimulating concentrations of A 23187 to higher values. A similar effect was observed with sera- and Con A-treated cells. The effect of sera and albumin was paralleled by a protecting effect of cells against high concentrations of A 23187.     

Membrane potential of squid axons: effect of internal and external ion concentration

Transmembrane resting potentials of squid axons were measured with variation of intracellular salt concentrations. It was found that the dependence of resting potential on the extracellular K-ion concentration was practically unaffected by the change of ionic strength in the intracellular phase, and the relationship of membrane potential and the logarithm of extracellular K-ion concentration was a straight line with a slope of about 50 mV/10-fold extracellular K-ion concentration. Also, the degree of change in resting potential due to the change of intracellular K-ion concentration was not affected appreciably by the extracellular solution with various K-ion concentrations, and the membrane potentials were insensitive over a wide range of intracellular K-ion concentrations. It was also indicated that the observed transmembrane potentials are not explained by a conventional membrane potential theory.     

Cytotoxicity of ionophore A23187 for basophils and other human blood cells.

The calcium ionophore A23187(A23) at concentrations exceeding 1 microgram/ml has been shown to be progressively cytotoxic for human blood basophils, neutrophils, lymphocytes, and erythrocytes. Toxicity to basophils was considered to be manifested by the increasing inability of 2-deoxyglucose (2DG) to inhibit histamine release (HR) at increasing concentrations of A23. The toxicity to neutrophils and lymphocytes was demonstrated by decreased lactate production (LP) after incubation with A23 of Ficoll-Hypaque fractions greatly enriched in each respective cell type. Red cells present in dextran-sedimented leukocytes were increasingly susceptible to lysis during washing subsequent to exposure to increasing concentrations of A23. A concentration of 4 microgram A23/ml, which is cytotoxic at 37 degrees C, produced optimal and noncytotoxic HR at 22 degrees C. It was possible to reduce A23 concentrations required for optimal HR by increasing Ca++ from 0.6 to 3 mM.     

The radiation induced reactions of aqueous polyethylene oxide solutions. II. Intrinsic viscosity changes in the pregel region

A model is proposed for the interpretation of molecular weight changes occurring in the pregel region of irradiated dilute aqueous polymeric systems. The model is, in principle, related to and gives results compatible with the molecular weight changes occurring during condensation polymerisation. On the basis of the above model and the ZIMM -KILB theory of branching effects on intrinsic viscosity, calculated intrinsic viscosities agree satisfactorily with results for low molecular weight material only when allowance is made for intramolecular crosslinking and a drastic reduction in the rate of intermolecular crosslinking with dose for doses close to the gel dose. A similar quantitative approach is not possible for higher molecular weight material because of the high branching densities involved. A qualitative approach shows that many features of the radiation induced behaviour of intrinsic viscosities can be explained by the proposed model. For concentrations below the critical concentration, a treatment based on diffusion control of intermolecular crosslinking was found to be satisfactory.