Atomic force and confocal microscopy for the study of cortical cells cultured on silicon wafers

The primary cortical cells were selected as a model to study the adherence and neural network development on chemically roughened silicon substrates without any coatings using confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM). The silicon substrates have a nano-range roughness (RMS) achieved by chemical etching using hydrofluoric (HF) acid. After 7 days of culturing, the neurons were observed to connect together and form dense neural networks. Furthermore, AFM results revealed that some porous structures at a few micrometer range existed between the neuron cells and the silicon substrates. It is suggested that the porous structures are made of extracellular matrix (ECM) components and play an important role in the neuronal adhesion and neurite outgrowth on the inert silicon wafers.

Hyaluronic acid hydrogel immobilized with RGD peptides for brain tissue engineering

In this paper, hyaluronic acid hydrogels with open porous structure have been developed for scaffold of brain tissue engineering. A short peptide sequence of arginine-glycine-aspartic acid (RGD) was immobilized on the backbone of the hydrogels. Both unmodified hydrogels and those modified with RGD were implanted into the defects of cortex in rats and evaluated for their ability to improve tissue reconstruction. After 6 and 12 weeks, sections of brains were processed for DAB and Glees staining. They were also labeled with GFAP and ED1 antibodies, and observed under the SEM for ultrastructral examination. After implanting into the lesion of cortex, the porous hydrogels functioned as a scaffold to support cells infiltration and angiogenesis, simultaneously inhibiting the formation of glial scar. In addition, HA hydrogels modified with RGD were able to promote neurites extension. Our experiments showed that the hyaluronic acid-RGD hydrogel provided a structural, three-dimensional continuity across the defect and favoured reorganization of local wound-repair cells, angiogenesis and axonal growth into the hydrogel scaffold, while there was little evidence of axons regeneration in unmodified hydrogel.

Regulation of charged groups and laminin patterns for selective neuronal adhesion

Primary neuronal cultures on substrates patterned with extracellular matrix proteins such as laminin have yielded much information regarding the physiological characteristics of neuronal cells in vitro. Surface charge also influences neuronal adherence, and a positive charge can have stimulatory effects. The attraction between laminin patterns and polycation films are of interest in the study of neuronal adhesion. We cultured primary hippocampal neurons on poly(ethylenimine) (PEI) films with laminin grids and evaluated their viability and morphology by means of fluorescent microscopy after 5-7 days. The results showed that the neurons did not form networks on the laminin grids. It is inferred that the PEI films were more favourable for neuronal adhesion than the laminin grid.

Hyaluronic acid-poly-D-lysine-based three-dimensional hydrogel for traumatic brain injury

Brain tissue engineering in the postinjury brain represents a promising option for cellular replacement and rescue, providing a cell scaffold for either transplanted or resident cells. In this article, a hyaluronic acid (HA)-poly-D-lysine (PDL) copolymer hydrogel with an open porous structure and viscoelastic properties similar to neural tissue has been developed for brain tissue engineering. The chemicophysical properties of the hydrogel with HA:PDL ratios of 10:1, 5:1, and 4:1 were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry. Neural cells cultured in the hydrogel were studied by phase-contrast microscope and SEM. The incorporation of PDL peptides into the HA-PDL hydrogel allowed for the modulation of neuronal cell adhesion and neural network formation. Macrophages and multinucleated foreign body giant cells found at the site of implantation of the hydrogel in the rat brain within the first weeks postimplantation decreased in numbers after 6 weeks, consistent with the host response to inert implants in numerous tissues. Of importance was the infiltration of the hydrogel by glial fibrillary acidic protein-positive cells-reactive astrocytes-by immunohistochemistry and the contiguity between the hydrogel and the surrounding tissue demonstrated by SEM. These findings indicated the compatibility of this hydrogel with brain tissue. Collectively, the results demonstrate the promise of an HA-PDL hydrogel as a scaffold material for the repair of defects in the brain.

AFM study of hippocampal cells cultured on silicon wafers with nano-scale surface topograph

The rat hippocampal cells were selected as model to study the interaction between the neural cells and silicon substrates using atomic force microscopy (AFM). The hippocampal cells show tight adherence on silicon wafers with nano-scale surface topograph. The lateral friction force investigated by AFM shows significant increase on the boundary around the cellular body. It is considered to relate to the cytoskeleton and cellular secretions. After ultrasonic wash in ethanol and acetone step by step, the surface of silicon wafers was observed by AFM sequentially. We have found that the culture leftovers form tight porous networks and a monolayer on the silicon wafers. It is concluded that the leftovers overspreading on the silicon substrates are the base of cell adherence on such smooth inert surfaces.

Hyaluronic acid hydrogel as Nogo-66 receptor antibody delivery system for the repairing of injured rat brain: in vitro

Nogo-66 and NgR are important receptors inhibiting neuronal regeneration and therefore are targets for treating CNS injury. Antagonists of this receptor including blocking antibodies are potential therapeutic agents for CNS axonal injuries such as spinal cord and brain trauma. A new antibody (IgG) releasing system has been developed by covalently attaching IgG to the biodegradable hyaluronic acid (HA) hydrogel via the hydrolytically unstable hydrazone linkage, aiming to deliver the antibody of CNS regeneration inhibitors to the injured brain. In this paper we describe the synthesis, physico-chemical characteristics and test results of biological activity of antibody released from hyluronic acid hydrogel. To form the conjugates the antibody is attached to the polymer backbone using a condensation reaction between aldehyde group of the antibody and hydrazide group of the HA hydrogel. Furthermore, pH sensitive linkage-hydrozone has been formed between hydrogel and antibody. The amount of conjugated antibodies can reach 135 microg antibody/mg hydrogel in the dry state. At low pH, the antibodies released quite fast. However, the antibodies released much slower in neutral and alkaline environment. The bioactivity of antibody released from hydrogel was retained as demonstrated by indirect immunofluorescence technique.

Electron holography study on the microstructure of magnetic tunnelling junctions

Electron holography was applied to study the microstructure evolution of magnetic tunnelling junctions (MTJs) CoFe/AlO(x)/Co annealed at different temperatures. A mean inner potential barrier was observed in the as-deposited MTJ sample, while it was changed to a potential well after a 200 degrees C or a 400 degrees C annealing. It is suggested that the oxygen atoms were redistributed during the annealing, which left metallic atoms acting as acceptors to confine the electrons, leading to the decrease of the potential of the AlO(x) barrier layer. The results suggest that the electron holography may be a useful tool for the study of the microstructure of amorphous materials.

Culture of neural cells on silicon wafers with nano-scale surface topograph

The adherence and viability of central neural cells (substantia nigra) on a thin layer of SiO(2) on Si wafers with different surface roughness were investigated. Variable roughness of the Si wafer surface was achieved by etching. The nano-scale surface topography was evaluated by atomic force microscopy. The adherence and subsequent viability of the cells on the wafer were examined by scanning electron microscopy (SEM) and fluorescence immunostaining of tyrosine hydroxylase (TH). It is found that the surface roughness significantly affected cell adhesion and viability. Cells survived for over 5 days with normal morphology and expressed neuronal TH when grown on surfaces with an average roughness (Ra) ranging from 20 to 50 nm. However, cell adherence was adversely affected when surfaces with Ra less than 10 nm and rough surfaces with Ra above 70 nm were used as the substrate. Such a simple preparation procedure may provide a suitable interface surface for silicon-based devices and neurones or other living tissues.

Aggregates and gel network structure of globin hydrolysates

A gel with excellent functional properties was prepared successfully using the hydrolysates of globin. In the present study, the structures of intermediate aggregates and gel network were observed directly with an electronic microscope. It was shown clearly that the intermediate aggregates were in a thin rod shape with a length of 130--140 nm, which was in good accordance with the results of the light scattering obtained in a previous study. The diameter of intermediate aggregates was 4--5 nm. Each unit of the intermediate aggregate was composed of beta-chain and peptide beta-1 in a ratio of 1:1. Its molecular weight was 26922 Da, and it had a diameter of 4.1 nm. The thin rod-shaped aggregates were formed with units through the hydrophobic interaction. The length of intermediate aggregate was >30--33 times the diameter. Furthermore, the cross-linked structure formed by peptide alpha-1 and the thin rod-shaped aggregates was also confirmed by the photography of the electronic microscope. These results supported the model proposed in previous papers as proper to depict exactly the formation and structure of the gel network of globin hydrolysates.

[Effects of tea polyphenols on microcirculation and antioxidation in aircrew]

OBJECTIVE

To study the effects of tea polyphenols (TP) on bulbi conjunctiva microcirculation (BCM) and antioxidation in aircrew and find out the proper antioxidant for the health protection of aircrew.

METHOD

Fourty healthy aircrew were divided into TP group (TP 600 mg/d.po) and control group (placebo) randomly. The effects of TP on microcirculation and antioxidation in aircrew were tested after 20 days.

RESULT

Red blood cell (RBC) superoxide dismutase (SOD) activity and GSH-PX (Whole blood glutathione peroxidase)/MDA (serum malondialdehyde) ratio in TP group were significantly higher than those in control (P<0.01), and serum MDA level was significantly decreased after TP administration (P<0.05). The numbers of capillaries and blood flow in micrangium were significantly increased, RBC aggregation, ischemia area and A (arteriole)/V (venule) ratio were remarkably decreased in TP group (P<0.01). The total integral value of microcirculation in TP group was significantly reduced in comparison with that in the control group.

CONCLUSION

TP can significantly increase the antioxidative ability of aircrew, decrease the BCM disturbance and improve the microcirculatory function.

The influence of aging on renal response to cadmium in Syrian hamsters

To determine the renal effects of cadmium (Cd) in older animals, we administered subcutaneously a single dose of cadmium, 3.0 mg/kg/BW, to Syrian hamsters aged 16 wk ("young") and 60 wk ("old"). Marked morphologic changes in the kidney and renal dysfunction were observed, especially in the older animals. The concentration of MDA in the renal cortex was significantly increased only in young hamsters treated with cadmium. Concentrations of glutathione (GSH) in the renal cortex were increased in the old hamsters on d 6. Increased levels of renal MDA after cadmium treatment may induce the production of GSH in the kidney thus preventing renal damage. Aging can increase the susceptibility to the renal effects of cadmium.

Effect of triethylenepentaminehexaacetic acid on the renal damage in cadmium-treated Syrian hamsters

Cadmium (Cd)-induced nephropathy was treated by triethylenepentaminehexaacetic acid (TTHA) in male Syrian hamsters. Hamsters injected three times a week with 3 mg/kg body wt CdCl2 showed proteinuria, urinary N-acetyl-beta-D-inglucosaminidase (NAG), and fractional excretion of sodium (FENa) when compared to saline-injected control. Cd-treated hamsters injected ip with TTHA 10 mg/kg body wt five times a week showed reduction of renal damage, including reductions in urinary protein (from 6.7 +/- 2.2 to 4.3 +/- 0.5 mg/d) and NAG (0.17 +/- 0.06 to 0.04 +/- 0.02 U/d). Urinary excretion of Cd was significantly increased (from 87 +/- 51.3 to 3052 +/- 1485 mg/L) by TTHA administration. Cd concentration in renal cortical tissue was slightly reduced (26.4 +/- 3.0 to 21.8 +/- 2.7 mg/g. protein). Excretion of malondialdehyde (MDA) was increased only in Cd-injected hamsters (to 2.1 +/- 1.6 nM/L), and elevated MDA in renal cortical tissue was not reduced by the administration of TTHA (1041 +/- 105 vs 1104 +/- 358 nM/g protein). Glutathione (GSH) concentration in the renal cortex was significantly elevated after Cd administration and further increased after TTHA administration (5.5 +/- 2.1 to 9.8 +/- 2.0 micrograms/50 mg protein). There were no marked effects on creatinine clearance (Ccr) and hematocrit. Moreover, renal morphological changes were improved significantly by treatment with TTHA. We demonstrated the efficacy of TTHA in the treatment of Cd-induced nephropathy in hamsters. Although the precise mechanism of the TTHA effects on Cd-induced nephropathy has not been elucidated, it might involve GSH reducing the elevated MDA concentration in renal tissue.

[Effects of neutral oil of Ligusticum sinense Oliv. on anoxia]

The neutral oil at 2.5 and 5.0g/kg P.O. can significantly decrease the oxygen consumption and prolong survival time for mice, increase the ability of tissues to tolerate anoxia and extend survival time under cerebral ischemic anoxia in mice. It can also inhibit the pituitrin-induced depression of S point in rats.

Aggregation of IGF-I receptors or insulin receptors and activation of their kinase activity are simultaneously caused by the presence of polycations or K-ras basic peptides

Several groups including us reported that basic proteins and polycations activate the insulin receptor tyrosine-specific protein kinase (TPK) in vitro. However, some inconsistency has become obvious in the observations. The most intriguing was the brief description by Morrison et al. [(1989) J. Biol. Chem. 264, 9994-10001] that polylysine had no effect on the IGF-I receptor TPK despite its 84% identity to the insulin receptor TPK. In the present study, we used highly purified IGF-I and insulin receptor TPKs in an effort to solve the discrepancies noted in the recent publications and to reveal the mechanism by which polycations stimulate the receptor TPKs. We report that the IGF-I receptor TPK is stimulated by polycations and basic proteins in a manner similar to their effects on the insulin receptor TPK. When effects of polylysine and polyarginine on both receptor TPKs were closely compared, subtle qualitative differences were found: Polylysine stimulated autophosphorylation and exogenous substrate phosphorylation activities of both insulin receptor TPK and IGF-I receptor TPK similarly. In contrast, another polycation, polyarginine, affected both TPKs in a manner quite different from polylysine: Polyarginine stimulated insulin receptor autophosphorylation to a greater extent than polylysine did while it had a very small effect on the IGF-I receptor autophosphorylation as well as the exogenous substrate phosphorylation activities of the two receptor TPKs. We have further extended the studies to include the domains of natural proteins which contain a polylysine-like sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation, characterization, and antitumor activity of water-soluble aminoalkanol platinum(II) complexes

A new series of highly water-soluble aminoalkanol platinum(II) complexes have been synthesized and characterized by elemental analysis, conductance, IR, and 195Pt NMR. Preliminary in vitro and in vivo screening tests for antitumor activities of these complexes against L1210 murine leukemia were performed. In general, these compounds were far less cytotoxic than cisplatin and possessed only a moderate degree of antitumor activity.

Substructural analysis of the insulin receptor by microsequence analyses of limited tryptic fragments isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence or presence of dithiothreitol

Human placental insulin receptor contains 47 Cys per an alpha beta dimer. Most of the 94 Cys in an intact alpha 2 beta 2 receptor are expected to form interchain or intrachain disulfide bonds, since there appears to be only one free cysteine residue in each beta subunit. In order to gain more insight into the three-dimensional organization of the insulin receptor, we have used limited trypsin digestion, SDS-PAGE, and protein microsequencing. The present study revealed the following; major tryptic cleavages occurred at alpha 164, alpha 270, alpha 582, and beta 1115, generating Mr 175,000, 130,000, 100,000, 70,000, and 55,000 disulfide-linked complexes. Under reducing conditions, tryptic fragments of Mr values = 30,000, 70,000, 20,000, 55,000, and 20,000 were identified to be alpha(1-164), alpha(165-582), alpha(165-270), alpha(271-582), and alpha(583-C-terminal), respectively. The major beta subunit tryptic fragment of Mr = 55,000 was assumed to have beta(724-1115) or beta(N-terminal-392). The Mr 175,000 complex appeared to contain two alpha(1-164) and two alpha(165-582), whereas the Mr 70,000 complex contained alpha(583-C-terminal) and beta(724-1115). Tryptic cleavage at alpha 582 apparently produced one Mr 175,000 and two Mr 70,000 complexes, suggesting that the alpha(583-C-terminal) domain interacts with the extracellular domain of the beta subunit by disulfide bonds. Tryptic cleavage at alpha 270 resulting in a formation of one Mr 100,000 complex consisting of two alpha(1-270) and two Mr 130,000 complexes consisting of alpha(271-C-terminal) and beta(724-1115) suggests that Cys residues involved with disulfide bonds between the two alpha subunits are located in the alpha(1-270) domain. The identification of the Mr 55,000 complex consisting of small tryptic fragments between alpha(122-270) indicates that 40 Cys residues in the two alpha(122-270) domains are inter- and intramolecularly associated by disulfide bonds. The alpha(1-121) domain does not appear to be linked to any other domains by disulfide bonds. These results are consistent with the structural model that the N-terminal domains of alpha subunits (122-270) are disulfide-linked together while the C-terminal domain (583-C-terminal) of the alpha subunit is linked to the N-terminal domain of the beta subunit by disulfide bonds.

Synthesis, characterization, and antitumor activity of 1,2-bis(diphenylphosphino) ethane platinum(II) and palladium(II) complexes

A number of 1,2-bis(diphenylphosphino)ethane monomeric platinum(II) and palladium(II) complexes have been synthesized in light of their potential antitumor activity. The metal center is coordinated with a number of carboxylate anions in the cis-configuration. These complexes have been characterized by elemental analysis, conductivity measurement, and various spectroscopic techniques [IR and 195Pt NMR]. In vivo screening tests for activity of these complexes were performed against the L1210/0 murine leukemia cancer model, but none displayed a significant level of antitumor activity.

[Effects of anisodamine on blood coagulation, fibrin and thrombosis in rabbits]

Anisodamine at dose of iv 10 and 20 mg/kg prolonged plasma prothrombin time, bleeding time and coagulation time, and showed positive reaction of plasma protamine paracoagulation test in conscious rabbits. The drug prolonged the thrombin time and reduced the contend of plasma fibrin. Anisodamine markedly inhibited blood platelet aggregation both in vitro and in vivo, dose-dependently. The extracorporeal thrombosis time was prolonged, the length and weight of thrombus was decreased after iv anisodamine 20 mg/kg. These results suggest that anisodamine has inhibitory action thrombosis and blood coagulation.

In vitro tyrosine phosphorylation studies on RAS proteins and calmodulin suggest that polylysine-like basic peptides or domains may be involved in interactions between insulin receptor kinase and its substrate

We have investigated the in vitro tyrosine phosphorylation of the HRAS and KRAS proteins by human placental insulin receptor kinase. Purified HRAS proteins are not phosphorylated by purified insulin receptor kinase. Since the tyrosine phosphorylation of calmodulin by the insulin receptor kinase in vitro requires cofactors such as protamine and poly(L-lysine), we examined the possibility that poly(L-lysine) may also potentiate the interaction between RAS proteins and the insulin receptor. We found that purified HRAS proteins are indeed phosphorylated by purified insulin receptor kinase in the presence of poly(L-lysine). In contrast, the KRAS protein, which carries an extremely basic domain (residues 172-182, Lys-Asp-Glu-Lys6-Ser-Arg), is phosphorylated by the receptor kinase without the addition of basic proteins. We then determined whether the KRAS basic domain peptide plays a role similar to that of poly(L-lysine) and found that both the HRAS protein and calmodulin are phosphorylated by the receptor kinase in the presence of the KRAS basic domain peptide. Further examination of the role of poly(L-lysine) in potentiating tyrosine phosphorylation of the HRAS protein and calmodulin by purified insulin receptor kinase indicates that poly(L-lysine) affects the conformation of these protein substrates as well as that of the receptor kinase domain. These studies suggest that polylysine-like basic proteins or domains are required to establish the interaction between insulin receptor kinase and its substrate.

Microsequence analysis of peptides and proteins. VIII. Improved electroblotting of proteins onto membranes and derivatized glass-fiber sheets

We have quantitatively examined the various parameters affecting the electrotransfer and sequence analysis of proteins from sodium dodecyl sulfate (SDS) gels to derivatized glass fiber paper or to polyvinyldifluoride (PVDF) membranes. Transfer yields in the range of 90-95% can be obtained for proteins in the molecular weight range of 10-90 kDa for transfer from 12% SDS gels to glass fiber paper derivatized with either QAPS (N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride) or APS (aminopropyltriethoxysilane). In order to achieve these yields, it was necessary to modify the conditions described by R. Aebersold et al. (J. Biol. Chem. 261, 4229-4238, 1986). We activated the glass fiber paper with dilute ammonia water and derivatized the activated glass fiber paper with QAPS and APS in anhydrous solvents which were allowed to slowly absorb moisture during the derivatization process. The transfer yield varied with transfer time versus molecular weight of the protein for a given percentage gel. Shorter transfer times and higher yields were obtained for higher molecular weight proteins on 8% gels. Lower molecular weight protein gave higher yields from 12% gels under similar transfer conditions. Sequencing yields of the transferred proteins were in the range of 40-80%, but a number of background peaks were observed on HPLC analysis of the phenylthiohydantoin amino acid derivatives. Transfer yields in the range of 85-95% were observed for similar experiments with PVDF membranes. In order to achieve these yields, it was necessary to modify the conditions described by P. Matsudaira (J. Biol. Chem. 262, 10035-10038, 1987). A lower voltage and longer transfer times gave higher transfer yields. In order to achieve consistently high transfer yields, it was also necessary to precoat the PVDF membranes with Polybrene. The PVDF membranes were cut into approximately 1-mm-wide strips and inserted into a continuous flow reactor (J. E. Shively, P. Miller, and M. Ronk, Anal. Biochem. 163, 517-525, 1987) for sequence analysis. Overall yields of samples loaded onto gels, electrotransferred to Polybrene-coated PVDF membranes, and sequenced ranged from 50-60% for beta-lactoglobin (10-50 pmol loaded onto SDS gels) to 20-30% for bovine serum albumin and soybean trypsin inhibitor (50 pmol loaded onto SDS gels). A comparison of the two methods shows clear advantages for the PVDF membranes over the derivatized glass fiber paper, including the ability to directly sequence the Coomassie blue-stained PVDF membranes, and the lower backgrounds observed on subsequent sequence analysis.