[Effect of noise on human mental performance]

OBJECTIVE

To investigate the effect of moderate noise on human thinking performance.

METHODS

During 2 h of exposure to 85, 90 dB(A), successive calculation, successive subtraction and determining figures according symbol were performed in 24 healthy young male subjects.

RESULTS

After l h exposure to noise of 85 dB(A), there were no significant changes in the accurate rate, correct number and total number of successive calculation, but the correct number and total number of successive subtraction decreased significantly as compared with control (P< 0.05). At 30 and 120 min exposure to noise of 90 dB(A), the mean reaction time prolonged, performance of reaction time decrease significantly (P<0.01) in the test of determining figures according symbol as compared with control; its total performance had a tendency of decrease, but was not significant. When the subjects were divided into two group according to their E score of EPQ, significantly different performance of accurate rate and different total performance were demonstrated in the test of determining figures according to symbol at 2 h of exposure under 90 dB(A) noise. The performance of extrovert was higher than that of introvert.

CONCLUSION

Moderate noise could affect performance of complex tasks with a higher workload and it had certain relationship with the personality of the subjects.

Expression of dentin sialoprotein (DSP) and other molecular determinants by a new cell line from dental papillae, MDPC-23

The purpose of this study was to characterize the molecular expression of a spontaneously immortalized and cloned cell line (MDPC-23) derived from 18-19 day CD-I fetal mouse molar dental papillae to determine if these cells were odontoblast-like. Western blots showed that a protein band, at approximately 105 kDa, reacting positively with anti-DSP antibodies and co-migrating with mouse DSP, was present in lysates of cells from passages 7, 37 and 77, in serum-free conditioned medium from passage 37 cells, and in mouse dentin extract. A minor band at 55 kDa was also apparent in cell lysates. Using a cDNA probe for a 486bp mouse DSP coding sequence, DSP or DSP-PP mRNA expression was detected by Northern analysis as well as Southern analysis after RT-PCR in all three passages. It was also shown that in these cells 1,25 (OH)2 vitamin D3 upregulated both osteopontin and osteocalcin mRNA, and dexamethasone downregulated alkaline phosphatase and alpha2(I) collagen mRNA. Thus, MDPC-23 cells express proteins which are common to mineralizing tissue. The expression of DSP and DSP-PP strongly suggests that this cell line is from the odontoblast lineage.

Neuropathology of ablation of rat gliosarcomas and contiguous brain tissues using a microplanar beam of synchrotron-wiggler-generated X rays

Adult-rat-brain tissues display an unusually high resistance to necrosis when serially irradiated with parallel, thin slices of a microplanar (i.e., microscopically thin and macroscopically broad) beam of synchrotron-wiggler-generated, approx. 35-120 keV (median approx. 50 keV) Gd-filtered X rays at skin-entrance absorbed doses of 312 to 5000 Gy per slice. Such microplanar beams were used to irradiate young adult rats bearing right frontocerebral 9L gliosarcomas (approx. 4 mm diameter), through a volume of tissue containing the tumor and contiguous brain tissue, either in a single array or in 2 orthogonally crossed arrays of tissue slices. Each array included 101 parallel microplanar slices, 100 microm center-to-center distance, each slice being approx. 25 microm wide and 12 mm high, with skin-entrance absorbed doses of 312.5 Gy or 625 Gy per slice. Compared with unirradiated controls with a median survival time of 20 days after tumor initiation, the median survival time was extended in irradiated rats by 139 days (625 Gy, crossed arrays), 96 days (312 Gy, crossed arrays) or 24 days (625 Gy, single array). The tumors disappeared in 22 of the 36 irradiated rats, 4/11 even after unidirectional microbeam irradiation. The extent and severity of radiation damage to the normal brain in rats with or without tumor was graded histopathologically. Correlation of those grades with radiation doses shows that loss of tissue structure was confined to beam-crossing regions and that only minor damage was done to zones of the brain irradiated unidirectionally.

In vivo comparison of three different porous materials intended for use in a keratoprosthesis

AIM

The goal was to compare the biological response of the corneal stroma with three porous materials: a melt blown microfibre web of polybutylene:polypropylene (80:20); a polyester spun laced fabric (polyethylene terephthalate), and an expanded polytetrafluoroethylene. Fifty per cent of each of the materials were modified using argon radio frequency.

METHODS

Discs (6 mm in diameter) were inserted into interlamellar stromal pockets and followed for a period of 12 weeks. Clinical evaluations were performed weekly. At 6 and 12 weeks, fibroplasia and the distribution of matrix proteins and growth factors (bFGF and TGF-beta) were evaluated immunohistochemically. The characterisation of glycosaminoglycans was determined after selective extraction and digestion.

RESULTS

The response to the disc resembled that of a wound with a decrease in keratan sulphate and an increase in dermatan sulphate. Pretreatment of the disc reduced corneal oedema and neovascularisation. Heparan sulphate, not normally detected in the corneal stroma, was detected in the region immediately surrounding the disc and in the discs of some materials. The presence of glycosaminoglycans and collagens in the disc indicated that cells had migrated into the disc and deposited a complex matrix in all three materials. The collagen response was not surface specific. bFGF and TGF-beta were detected in the region between the disc and the stroma in the polybutylene material and became diffuse with time.

CONCLUSION

Fibroplasia occurred most rapidly into the polyester discs but was accompanied by a large number of inflammatory cells. While the distribution of collagens was not altered by the material, the expression and distribution of growth factors was material dependent. bFGF was expressed transiently and occurred before that of TGF-beta. It is predicted that the transient expression of growth factors mediates the regulation of matrix proteins.

Effect of interparticulate interaction on release kinetics of microsphere ensembles

The release kinetics of microsphere ensembles is complicated by the mutual influence of the microspheres which are entrapped in small compartments such as body cavities. This work focused on the effect of interparticulate interaction on the release kinetics of microsphere ensembles with limited spreading. Experiments and finite element modeling were conducted to investigate diffusional drug release from a single sphere, a monolayer, and multiple layers of microspheres. Poly(methyl methacrylate-co-methacrylic acid) (P(MMA/MAA)) microspheres and azidothymidine (AZT) were used in the experiments. The order of the release rate of AZT from various microsphere populations was observed to be single sphere > monolayer > multiple layers. This evidenced the importance of interparticulate interaction. The finite element simulations elucidated the influence of various factors on the release kinetics of microsphere ensembles including the separation distance, location of the spheres, and the drug accumulation in the medium. Calibration of overall release kinetics for the neighboring effect was proposed on the basis of the spreading factor. Overall release profiles of microsphere ensembles were predicted using the release profiles of individual microspheres at various locations.

Finite element analysis of diffusional drug release from complex matrix systems. II. Factors influencing release kinetics

This work concentrated on the analysis of several factors influencing the kinetics of diffusional drug release from complex matrix devices, such as convex tablets and rings, into a finite volume. These factors include initial drug concentration distribution, anisotropic matrix, and time- and concentration-dependent diffusion coefficients. The individual and comprehensive effects of these factors on the release kinetics were investigated by the finite element method. Errors introduced by neglecting drug diffusion through the ends of edges of cylindrical devices were estimated by comparison of the 1-D models with the 2-D cylinder model. The influence of side-wall coating on the accuracy of the prediction of release profiles by the 1-D slab model for cylindrical devices was studied using various coating materials of different permeabilities. The analyses carried out in this work could assist the design of the complex matrix systems required for controlled drug release.

Implantation of a synthetic cornea: design, development and biological response

Our goal was to evaluate 3 different designs of synthetic corneas in vivo. All devices had a transparent hydrogel center molded to a porous peripheral skirt. Over 30 devices were implanted into rabbits and followed for up to 6 months. The devices were preseeded with rabbit stromal fibroblasts, which enhanced the rate of fibroplasia. The anterior surface of the hydrogel was modified using argon rf plasma treatments. Clinical examinations were performed, and histological analyses were conducted on tissue throughout the time course. Our optimal model ranged from 4.5 to 6 mm and had an extended porous skirt increasing the surface area for fibroplasia and ultimate anchorage of the device. Fibroplasia occurred in this model, and collagen was detected by 28 days. The anterior chamber was normal with no detectable leakage of aqueous humor. Glycosaminoglycans were detected and followed the time course outlined previously when porous material itself was inserted into the stroma. We present the first demonstration that rabbit limbal epithelial cells can migrate onto the synthetic cornea in vivo.

The expression of integrin subunits alpha 6 and beta 4 by corneal epithelial cells on modified hydrogel surfaces

Our goal was to quantitate the expression and localization of integrin subunits alpha 6 and beta 4 by corneal epithelial cells on defined synthetic substrates. Previously we demonstrated that the cytoplasmic pH and translocation of the alpha 6 integrin subunit to the cell membrane was modified by ionic interactions. These results suggest that changes in the ionic interactions at the cell-substrate interface not only alter the intracellular milieu but ultimately affect the expression of adhesion proteins. To test this hypothesis, hydroxyethylmethacrylate (hema) hydrogels were modified by the addition of amines (N,N-dimethylaminoethylmethacrylate) or carboxyl moieties (methacrylic acid). Changes in the distribution of mRNA and protein were monitored using confocal laser scanning microscopy. The steady state level of integrin mRNA was evaluated, and the results indicate that while the plating efficiency was identical on all surfaces, the expression and localization of integrin subunits was surface dependent. Alpha 6 and beta 4 proteins were localized along the basal surface of nonpermeabilized cells cultured on laminin, on surfaces with amine moieties, and on those with amine and carboxyl moieties. The level of diffuse cytoplasmic staining increased with the presence of carboxyl moieties. Alpha 6 and beta 4 integrin subunits were negligible when the surfaces contained carboxyl moieties alone. The expression of alpha 6 and beta 4 mRNA was higher on surfaces containing amine moieties than on surfaces containing only carboxyl moieties. These results indicate that the characteristics of the substrate and the resulting cell-matrix interaction alter protein and mRNA expression of integrin subunits.

[Effects of anti-rhTNF alpha monoclonal antibody on oxygen extraction in endotoxemic rabbits]

The effects of anti-rhTNF alpha monoclonal antibody (McAb) on oxygen extraction in endotoxemia rabbits were observed by decreasing total oxygen delivery (DO2) with progressive hypoxia. The result showed that the DO2-VO2 relationship in anti-rhTNF alpha McAb group, like the control group, could be clearly divided into "independent" and "dependent" segment, while the non-correlated antibody group, like the endotoxemic group, never presented any plateau upon breathing the air. Critical oxygen delivery (DO2C) and pooled oxygen extraction rate (ER) in anti-rhTNF alpha McAb group were respectively 10.18 +/- 3.21 ml/(min.kg) and 0.690, not significantly different from those in the control group (10.18 +/- 1.69 and 0.730). The ER in non-correlated antibody group was 0.408, which was significantly lower than that in anti-rhTNF alpha McAb group (P < 0.05), while the plasma TNF alpha concentration was significantly higher (P < 0.01). It was concluded that the monoclonal antibody of recombinant human tumor necrosis factor could block or even reverse the pathologic process of oxygen extraction deficiency caused by endotoxemia.

Protective effect of transfection with secretable superoxide dismutase (SOD) (a signal sequence-SOD fusion protein coding cDNA) expression vector on superoxide anion-induced cytotoxicity in vitro

For ex vivo gene therapy, superoxide dismutase (SOD) must be secreted into the extracellular space and delivered to damaged cells. Recombinant DNA technique can be used to produce a secretory protein that is fused to a non-secretory protein and a signal peptide of another secretory protein gene. We constructed a secretable SOD eukaryotic expression vector which expresses human SOD cDNA by fusing it to the signal peptide DNA sequence of the human interleukin-2 (IL-2) gene. The ILSOD cDNA constructed by PCR-based gene expression was ligated into the multicloning site of the pRc/CMV plasmid (pRc/CMV-ILSOD). Rat lung epithelial like cells (L2 cells) were transfected with pRc/CMV-ILSOD by lipofection. The extracellular SOD activity of ILSOD-L2 cells (transfected cells with pRc/CMV-ILSOD) was 3 times as high as that of host cells. We used the xanthin (X)/xanthin oxidase (XO) system to produce superoxide anions at the extracellular space. We initially investigated the direct cytotoxicity of superoxide anions upon cells. Host and ILSOD-L2 cells were killed by using X/XO, although the sensitivity of the ILSOD-L2 cells to X/XO induced cytotoxicity was significantly decreased compared with that of host cells. The production of lipid peroxidated substances in the host in the presence of X/XO increased to about twice the control (absence of X/XO) level. However, that of ILSOD-L2 cells did not change in the presence of X/XO. Therefore, ILSOD-L2 cells were resistant to X/XO induced lipid peroxidation. These findings indicated that ILSOD gene transfection protected against direct oxidant stress by X/XO. We then investigated the effect of extracellular SOD secreted from ILSOD-L2 cells on extracellular superoxide anion induced cytotoxicity in normal cells. The conditioned media of host cells had no significant effect upon X/XO induced cytotoxicity. However, the conditioned media of ILSOD-L2 cells protected against X/XO induced cytotoxicity. Furthermore, the conditioned medium of ILSOD-L2 cells was more effective than that of host cells against the production of lipid peroxidated substances by normal cells under conditions of oxidative stress. These results indicated that non-secretable protein could be delivered to target cells by means of DNA engineering. This strategy could thus provide an ex vivo means of applying gene therapy using non-secretable proteins.

Acquired resistance to Borrelia burgdorferi infection in the rabbit. Comparison between outer surface protein A vaccine- and infection-derived immunity

Intradermal inoculation of the rabbit with Borrelia burgdorferi, sensu lato, results in the consistent development of erythema migrans (EM), dermal infection, and visceral dissemination of the spirochete. Within 5 mo, EM as well as dermal and visceral infection are cleared and the animals exhibit immunity to reinfection. This study compares infection-derived immunity with acquired resistance resulting from the administration of a lipidated recombinant outer surface protein A (OspA) vaccine presently undergoing human trial. 4 of 11 OspA vaccinated rabbits, challenged intradermally at each of 10 sites with 10(5) low passage B. burgdorferi, developed EM as well as dermal and disseminated infection. After identical challenge, 2 of the 11 infection-immune rabbits developed a dermal infection, but not EM or disseminated infection. Further, ELISA anti-OspA titers did not correlate with the status of immunity for either OspA vaccinated or infection-immune rabbits. Prechallenge ELISA anti-OspA titers were relatively low in the infection-immune group. This study demonstrates that a state of partial immunity to experimental Lyme disease may result that could potentially mask infection. Further, our data strongly suggest that immunogen(s) other than OspA is/are responsible for stimulating acquired resistance in the infection-immune rabbit.

Single-and dual-energy CT with monochromatic synchrotron x-rays

We explored the potential for clinical research of computed tomography (CT) with monochromatic x-rays using the preclinical multiple energy computed tomography (MECT) system at the National Synchrotron Light Source. MECT has a fixed, horizontal fan beam with a subject apparatus rotating about a vertical axis; it will be used for imaging the human head and neck. Two CdWO4-photodiode array detectors with different spatial resolutions were used. A 10.5 cm diameter acrylic phantom was imaged with MECT at 43 keV and with a conventional CT (CCT) at 80 kVp: spatial resolution approximately equal to 6.5 line pairs (lp)/cm for both; slice height, 2.6 mm for MECT against 3.0 mm for CCT; surface dose, 3.1 cGy for MECT against 2.0 cGy for CCT. The resultant image noise was 1.5 HU for MECT against 3 HU for CCT. Computer simulations of the same images with more precisely matched spatial resolution, slice height and dose indicated an image-noise ratio of 1.4:1.0 for CCT against MECT. A 13.5 cm diameter acrylic phantom imaged with MECT at approximately 0.1 keV above the iodine K edge and with CCT showed, for a 240 micrograms I ml-1 solution, an image contrast of 26 HU for MECT and 13 and 9 HU for the 80 and 100 kVp CCT, respectively. The corresponding numbers from computer simulation of the same images were 26, 12, and 9 HU, respectively. MECT's potential for use in clinical research is discussed.

Extracellular Mg2+ regulates intracellular Mg2+ and its subcellular compartmentation in fission yeast, Schizosaccharomyces pombe

Effects of extracellular magnesium ions ([Mg2+]o) on intracellular free Mg2+ ([Mg2+]i) and its subcellular distribution in single fission yeast cells, Schizosaccharomyces pombe, were studied with digital-imaging microscopy and an Mg2+ fluorescent probe (mag-fura-2). Using 0.44 mM [Mg2+]o, [Mg2+]i in yeast cells was 0.91 +/- 0.08 mM. Elevation of [Mg2+]o to 1.97 mM induced rapid (within 5 min) increments in [Mg2+]i (2.18 +/- 0.11 mM). Lowering [Mg2+]o to 0.06 mM, however, exerted no significant effects on [Mg2+]i (0.93 +/- 0.14 mM), at least for periods of up to 30 min. Irrespective of the [Mg2+]o used, the subcellular distribution of [Mg2+]i remained heterogeneous, i.e. where the sub-plasma membrane region > cytoplasm > nucleus. [Mg2+] in all three subcellular compartments increased significantly, two- to threefold, concomitant with [Mg2+] when placed in 1.97 mM [Mg2+]o. We conclude that [Mg2+]i in fission yeast is maintained at a physiologic level when [Mg2+]o is low, but intracellular free Mg2+ rapidly rises when [Mg2+]o is elevated. Like most eukaryotic cells, yeast may have a Mg2+ transport system(s) which functions to maintain gradients of Mg2+ from the outside to inside the cell and among its subcellular compartments.

[Cell cycle and apoptosis]

The progression of cell cycle in embryonic cells from oceanic bionts to mammalians is initiated, promoted and terminated under the regulation of cell cycle gene products, named cyclins, and a p34 (cdc 2). Besides, oncogene (proto-oncogene) products such as p53 and pRB also directly regulate the progression of cell cycle. However, the p34 (cdc 2) which promotes the mitotic cell division also initiates the apoptosis of certain cells. Therefore, mutations of genes that regulate the normal progression of cell cycle would cause cells in the cell cycle undergoing either apoptosis or uncontrollable proliferation.

[Effect of oxygen therapy on the postoperative patient under general anesthesia]

Adequate oxygen administration has shown a definite benefit for preventing postoperative patients from hypoxia after weaning. Nosal cannula of 3L/min flow rate may maintain a satisfactory blood gas result. For its easy and effective. It should be recommended as a routine intervention of postoperative oxygen therapy especially for those patient whose respiratory function were normal before surgery.

Effect of transfection with a superoxide dismutase expression plasmid on xanthine/xanthine oxidase-induced cytotoxicity in cultured rat lung cells

We inserted human Cu, Zn-superoxide dismutase (hSOD) cDNA into the eukaryotic expression plasmid (pRc/CMV) under the control of the cytomegalovirus promoter. The hSOD expression plasmid (pRc/CMV-SOD) was transfected in L2 cells by mean of lipofection. The intracellular SOD activity in pRc/CMV-SOD transfected cells (CMV-SOD cells) was about twice that in host cells. However the level of extracellular SOD activity was similar in CMV-SOD and host cells. When exposed to xanthine (X)/xanthine oxidase (XO) to generate active oxygen species, significantly more CMV-SOD cells than host cells survived. The production of lipid peroxidation in host cells significantly increased in the presence of X/XO, but that in CMV-SOD cells did not change. Thus, transfection with SOD gene effectively prevented X/XO-induced cytotoxicity. The results indicated that increasing the level of intracellular SOD activity protected cells against extracellular superoxide anion stress.

Effect of transfection with superoxide dismutase expression plasmid on superoxide anion induced cytotoxicity in cultured rat lung cells

Human Cu, Zn-superoxide dismutase (hSOD) cDNA was inserted into a eukaryotic expression plasmid (pRc/CMV) under the control of a cytomegalovirus promoter. The hSOD expression plasmid (pRc/CMV-SOD) was transfected into L2 cells by means of lipofection. The integration of the hSOD gene in genomic DNAs in the cells transfected with pRc/CMV-SOD plasmid was examined by Southern blotting using hSOD cDNA as the probe. However, Southern blots of host cells (without transfection) and CMV cells (pRc/CMV plasmid transfection) indicated no hybridization of hSOD cDNA. Western blots indicated that hSOD was expressed in CMV-SOD cells. The SOD activity in CMV-SOD cells was about twice that in host and CMV cells. Furthermore, this SOD activity in CMV-SOD cells was enhanced for 60 d after the selection of cell clones. After exposure to paraquat and catalase, about 90% of the CMV-SOD cells survived compared with the untreated controls, whereas about 60% of the host cells survived. The production of lipid peroxidation in host cells increased significantly after exposure to both paraquat and catalase, whereas that in CMV-SOD cells did not change. The correlation between the surviving cells and lipid peroxidation was inverse. These results indicated that transfection with the SOD gene was effective against superoxide anion induced cytotoxicity.

A high-performance neural network for solving linear and quadratic programming problems

Two classes of high-performance neural networks for solving linear and quadratic programming problems are given. We prove that the new system converges globally to the solutions of the linear and quadratic programming problems. In a neural network, network parameters are usually not specified. The proposed models can overcome numerical difficulty caused by neural networks with network parameters and obtain desired approximate solutions of the linear and quadratic programming problems.

Distribution of F-actin, vinculin and integrin subunits (alpha 6 and beta 4) in response to corneal substrata

Our goal was to determine the early response of corneal epithelial cells to living modified stromal substrates. We examined the distribution of integrin subunits (alpha 6 and beta 4), vinculin and the organization of F-actin in epithelial cells after cell-matrix and cell-cell hypothesized that the distribution of proteins in the cell matrix attachment complex would be altered if the substrate was modified. Integrin subunits, alpha 6 and beta 4, were chosen as they play a role in cell matrix adhesion and adhesion site formation. Corneal epithelial cells were cultured from explants and seeded on three corneal substrates (a stroma containing an intact basal lamina, a cornea lacking a basal lamina and a cornea treated with alkali). After 3 h of incubation, the tissue was fixed and stained with monoclonal antibodies specific for vinculin and for the integrin subunits alpha 6 and beta 4. The organization of F-actin was assessed using rhodamine phalloidin. The localization of the proteins was recorded with confocal laser scanning microscopy. Filamentous actin delineated the lateral cell membranes of corneal epithelial cells. The organization of actin and distribution of vinculin and integrin subunits of epithelial cells cultured on stromal substrates containing a basal lamina mimicked a simple epithelial organization. In contrast, when cells are cultured on the substrate lacking a basal lamina and alkaline treated corneal substrates the distribution of the specific proteins examined was altered. Vinculin and alpha 6 were present along membranes of cells cultured on substrates lacking a basal lamina and were diffuse in cells cultured on the alkaline substrates. These studies demonstrate that changes in the distribution of adhesion and cytoskeletal proteins in response to different surfaces may contribute to the healing dynamics in different wounds.

Expression of integrin and organization of F-actin in epithelial cells depends on the underlying surface

PURPOSE

To evaluate the role of ionic interactions in the cell surface expression of integrins and the organization of F-actin. Understanding these interactions will allow the development of surfaces for prosthetic purposes that will promote the normal expression of adhesion proteins.

METHODS

Hema (hydroxyethylmethacrylate) hydrogels were used to mimic the charges present on extracellular matrix proteins. The surfaces were modified by the addition of amines (N,N-dimethylaminoethylmethacrylate; NDAM) or carboxyl moieties (methacrylic acid). The effects of ionic interactions on cellular spreading and on the expression of proteins were examined by modification of the stoichiometrically defined amounts of positive and negative charges on the Hemas. Changes in intracellular pH and the distribution and localization of protein were monitored using fluorescent markers, spectrofluorometry, and confocal laser scanning microscopy, respectively. The immunohistochemical studies were confirmed by flow cytometric analysis.

RESULTS

The data indicate that although cells adhered to all the surfaces, the number of cells possessing adhesion receptors is significantly greater on surfaces with amine functionalities. Cell seeding and plating efficiency after 2 hours were identical on all surfaces. The intracellular pH of epithelial cells grown on surfaces containing NDAM, a tertiary amine, was higher than that of cells grown on Hemas containing only methacrylic acid. Lamellipodial extensions and an extensive actin network were present on surfaces containing 5% NDAM. The alpha 6 subunit was localized along the lateral cell membranes. The alpha 2 and 3 subunits were present along cell membranes and at lamellipodial extensions. Cells cultured on surfaces containing only methacrylic acid did not spread. Actin filaments were not detected, and alpha 6 was negligible on these surfaces.

CONCLUSIONS

This is a novel approach to understanding cell-substrate interactions, and one that allows quantitative evaluation of the response of cells to defined surfaces. The organization of F-actin is altered by the substrates containing only carboxyl moieties. The distribution of integrin subunits is also altered by the substrate. These results indicate that epithelial cell spreading and protein expression may be regulated by ionic interactions.