Effect of influenza A virus on ciliary activity and dye transport function in the chinchilla eustachian tube

Previous studies have shown that influenza A virus inoculated via a transbullar approach can cause severe disorders of the chinchilla eustachian tube. In this study, we inoculated chinchillas both intranasally and transbullarly with influenza A virus (A/Alaska/6/77) to assess the effect of this virus on both the ciliary activity of eustachian tube epithelium and eustachian tube transport function. Data indicated that while the nature of the major lesions was indistinguishable, the differing routes of inoculation did influence the time course and initial location of virus-induced histopathology. Analysis of ciliary beat frequency and dye transport function indicated a maximal decrease approximately 7 to 14 days postinoculation, with return to normal function by 28 days postinoculation. Light and transmission electron microscopic observations of the evolution of histopathology and return to normal histology correlated well with functional assessment data.

Living donor nephrectomies-right side--intraoperative assessment of the right renal vascular pedicle in 112 cases

Generally, the left kidney from a living donor is more commonly preferred but the right kidney is occasionally donated because of multiple left renal arteries or repeated transplantation. The right donor nephrectomy is usually more difficult compared to the left because the right renal vein is often multiple and short, which complicates dissection of the vascular pedicle. From Jan. 1989 to Sep. 1992, 112 consecutive cases of right donor nephrectomies out of a total of 771 cases were retrospectively reviewed with the preoperative renal angiography and the intraoperative assessment of the right renal vascular pedicle. The indications for right donor nephrectomy include 1) multiple or proximal bifurcating renal arteries of the left kidney (89.3%), 2) repeated transplantation in the recipient (9%). In 26.8% of the cases, there were more than two right renal veins. In the right donor nephrectomy, it is often necessary to perform vena cava cuff resection because of short and frequently occurring multiple right renal veins. For the dissection of the inferior vena cava (IVC), the aberrantly occurring right gonadal vein, the adrenal vein draining above the junction of the renal vein and IVC, and the lumbar vein below the junction should always be looked for and must be ligated if any are found.

The relationship of monkey frontal eye field activity to saccade dynamics

1. In this study, we compared the temporal waveforms of the activity of monkey frontal eye field movement neurons with the dynamics of saccadic eye movements. 2. Movement neurons in the frontal eye field were selected according to previously published criteria. They had little or no response to visual stimuli in a fixation task, and equivalent activity before visually guided and memory-guided saccades. We studied corticotectal neurons and corticopontine neurons identified by antidromic excitation, as well as neurons whose projections were not identified. 3. These neurons had a peak activation at a mean of 13 ms before the saccade began. However, rather than falling off rapidly as the saccade ended, most neurons continued to fire after the saccade, returning to baseline at a mean of 93 ms after the end of the saccade. 4. We measured the decrement in activity for these neurons during the saccade. Although a few neurons showed decrements of > 60% of their peak activity level, the average activity dropped only 16.9%, with some neurons actually showing a rise in activity during the saccade. If we ignored the latency between peak in activity and saccade start and measured the fall in activity for a period equal to one saccade duration after the peak, the average drop in activity was still only 34.9%. Thus the activity of these neurons did not appear to be closely related to dynamic motor error, which falls from its maximum value to zero over the time course of a saccade. 5. These results suggest that a focus of movement activity within the topographic map in the frontal eye field specifies the amplitude and direction for an impending saccade, whereas the peak of movement activity signals the time to initiate a saccade. 6. Unlike the superior colliculus, the activity of frontal eye field movement neurons does not appear to be related to dynamic events that occur during the saccade, such as motor error.

An element of the transforming growth factor-beta 1 5'-untranslated region represses translation and specifically binds a cytosolic factor

In many cell types, there is a discrepancy between transforming growth factor-beta 1 (TGF-beta 1) mRNA and TGF-beta 1 protein, suggesting that expression of TGF-beta 1 is regulated posttranscriptionally. We have previously shown that a 137-nucleotide (nt) region of the TGF-beta 1 5'-untranslated region (UTR) potently inhibits the expression of a heterologous reporter gene, suggesting a role for this region in the posttranscriptional inhibition of TGF-beta 1 expression. To study the mechanism of inhibition, a chimeric plasmid containing this region of the TGF-beta 1 5'-UTR and the reading frame of the human GH gene was stably transfected into C2C12 myoblastic cells. Our results show that the TGF-beta 1 5'-UTR inhibits GH expression by inhibiting GH mRNA translation. In vitro gel retardation and cross-linking assays using a radiolabelled RNA probe transcribed from this region of the TGF-beta 1 5'-UTR demonstrate the specific binding of a cytosolic factor. Deletion of a potential stem-loop-forming region abolishes binding of this factor and partially restores GH production. These results suggest that posttranscriptional inhibition of TGF-beta 1 expression is at the level of mRNA translation and that a cytosolic factor may regulate TGF-beta 1 mRNA translation.

Development of secretory elements in murine tubotympanum: lysozyme and lactoferrin immunohistochemistry

Secretory activity, particularly of antibacterial agents such as lysozyme and lactoferrin, is an important aspect of the mucosal defense mechanism, and the development of these agents may have a direct bearing on the susceptibility of the ear to infection. In this study, the secretory cells of the murine tubal epithelium were first observed at gestational day 17. Although tubal glands began to develop on gestational day 18, their secretory activity was first shown on postnatal day 3. The number of secretory cells of the tubal epithelium increased rapidly immediately after birth, while that of the tubal glands showed a gradual increase from postnatal day 3. The epithelial secretory cells in the tubotympanum matured at birth, but the tubal glands matured gradually after birth. Lysozyme was first recognized in the epithelial secretory cells on postnatal day 1, while lactoferrin was first detected in the tubal glands on postnatal day 3. Both lysozyme and lactoferrin were co-localized in the serous cells of the tubal glands. The secretion of lysozyme and lactoferrin seemed to reflect the maturation of the secretory cells in the murine tubotympanum.

Albumin grafting on to polypropylene by thermal activation

4-azido-2-nitrophenyl albumin (ANP-albumin) was prepared by reacting 4-fluoro-3-nitrophenyl azide with albumin. The thermal decomposition kinetics of phenyl azide of ANP-albumin was studied at various temperatures by Fourier-Transform Infrared (FTIR) spectroscopy. The decomposition rate of the phenyl azide increased with temperature. The activation energy for the first-order decomposition of the phenyl azide was 128.0 kJ/mol. Albumin was grafted on to polypropylene (PP) films by thermolysis of the azido groups of ANP-albumin with no premodification of the PP surface. The albumin-grafted surface was characterized by electron spectroscopy for chemical analysis (ESCA) and by quantitative determination of platelet adhesion and activation. The bulk concentration of ANP-albumin used for adsorption varied from 0.001 to 30 mg ml-1, and the albumin-adsorbed PP films were incubated at 100 degrees C for up to 7 h. The carbon and nitrogen peaks resulting from the grafted albumin were used to compare the surface albumin concentrations as a function of the concentration of ANP-albumin in the adsorption solution. When the PP film was adsorbed with ANP-albumin at the concentration of 5 mg ml-1 or higher and incubated at 100 degrees C for longer than 5 h, the surface became resistant to platelet adhesion. The ANP-albumin can be grafted on to chemically inert surfaces such as PP surface through simple thermolysis of azido groups to prevent platelet adhesion and activation.

Conformational change of chaperone Hsc70 upon binding to a decapeptide: a circular dichroism study

The conformation of bovine Hsc70, a 70-kDa heat shock cognate protein, and its conformational change upon binding to decapeptides, was studied by CD spectroscopy and secondary structure prediction (Chou, P.Y. & Fasman, G.D., 1974, Biochemistry 13, 222-245). The CD spectra were analyzed by the LINCOMB method, as well as by the convex constraint analysis (CCA) method (Perczel, A., Park, K., & Fasman, G.D., 1992, Anal. Biochem. 203, 83-93). The result of the CD analysis of Hsc70 (15% alpha-helix, 24% beta-sheet, 24% beta-turn, and 38% remainder) was very similar to the predicted secondary structure for the beta-sheet (24%) and the beta-turn (29%). However, there is disagreement between the alpha-helical content by CD analysis (15%) and the predicted structure (30%). In spite of the fact that the decapeptides contained a considerable amount of beta-sheet (22%), the interaction of the heat shock protein with the peptide resulted in an overall decrease in the content of beta-sheet conformation (-15%) of the complex. This may be due to induction of a molten globule state. The result of the CCA analysis indicated that the Hsc70 undergoes a conformational change upon binding the decapeptides.

Identification of a transcriptional initiator element in the cytochrome c oxidase subunit Vb promoter which binds to transcription factors NF-E1 (YY-1, delta) and Sp1

We have mapped the basal promoter activity of the mouse cytochrome c oxidase (COX) subunit Vb gene to the -17 to +20 region which contains two putative ets binding sites flanking an NF-E1 site fused to an Sp1 site. A 17-nucleotide sequence flanking the major transcription start site (-8 to +9), referred to as 17Inr (initiator sequence) was able to drive CAT activity in 3T3 cells to a level comparable to the construct containing sequences -17 to +20. This suggests that the 17Inr sequence contains the initiator activity. The 17Inr contains a pyrimidine-rich sequence, commencing with a CA that corresponds to the major transcription start site. Primer extension of RNA from transfected cells demonstrated that transcription initiation with the 17Inr template occurs at a site identical to the endogenous gene. DNA-protein binding by gel mobility shift and methylation interference analyses indicated that the pyrimidine-rich sequence immediately flanking the transcription start site consists of an NF-E1 factor binding motif with an overlapping upstream Sp1 binding site. A 13-nucleotide sequence, 13Inr (-4 to +9), which retains the NF-E1 binding activity but does not bind Sp1, was able to promote chloramphenicol acetyltransferase gene expression at levels similar to the 17Inr sequence, suggesting that NF-E1 factor binding is critical for initiator function. Finally, using an in vitro transcription system from Drosophila embryos we demonstrate that NF-E1 is necessary for transcription activation of both the 17Inr and the 13Inr initiator templates. Thus NF-E1 binding appears to be important for basal promoter function of the mouse COXVb gene.

Surface modification of polymeric biomaterials with poly(ethylene oxide), albumin, and heparin for reduced thrombogenicity

Appropriate surface modification has significantly improved the blood compatibility of polymeric biomaterials. This article reviews methods of surface modification with water-soluble polymers, such as polyethylene oxide (PEO), albumin, and heparin. PEO is a synthetic, neutral, water-soluble polymer, while albumin and heparin are a natural globular protein and an anionic polysaccharide, respectively. When grafted onto the surface, all three macromolecules share a common feature to reduce thrombogenicity of biomaterials. The reduced thrombogenicity is due to the unique hydrodynamic properties of the grafted macromolecules. In aqueous medium, surface-bound water-soluble polymers are expected to be highly flexible and extend into the bulk solution. Biomaterials grafted with either PEO, albumin, or heparin are able to resist plasma protein adsorption and platelet adhesion predominantly by a steric repulsion mechanism.

Photografting of albumin onto dimethyldichlorosilane-coated glass

4-Azido-2-nitrophenyl albumin (ANP-albumin) was prepared by displacing the fluoro group of 4-fluoro-3-nitrophenyl azide (FNPA) by an amino group of albumin. Photolysis of phenyl azides of ANP-albumin was studied by Fourier-transform infrared (FTIR) spectroscopy. The band of phenyl azide disappeared completely after a 12-min exposure to long wave UV light (366 nm), and the photolysis was first-order. Albumin was grafted onto dimethyldichlorosilane-coated glass (DDS-glass) by photolysis of the azido groups of ANP-albumin without any premodification of the surface. The albumin-grafted DDS-glass was characterized by determining the relative amount of nitrogen resulting from the grafted albumin on the surface using electron spectroscopy for chemical analysis (ESCA). The amount of nitrogen increased when the concentration of ANP-albumin in the adsorption solution increased up to 0.1 mg/ml. As the solution concentration increased above this value, the amount of nitrogen decreased. The platelet resistance of the albumin-grafted surfaces was evaluated by measuring the number of adherent platelets and the extent of activation that was quantitated by the area of platelets spread on the surfaces. The maximum platelet-resistant effect was observed when the ANP-albumin was adsorbed for more than 50 min at the solution concentration ranging from 0.05 to 10 mg/ml.

Functional antagonism between YY1 and the serum response factor

The rapid, transient induction of the c-fos proto-oncogene by serum growth factors is mediated by the serum response element (SRE). The SRE shares homology with the muscle regulatory element (MRE) of the skeletal alpha-actin promoter. It is not known how these elements respond to proliferative and cell-type-specific signals, but the response appears to involve the binding of the serum response factor (SRF) and other proteins. Here, we report that YY1, a multifunctional transcription factor, binds to SRE and MRE sequences in vitro. The methylation interference footprint of YY1 overlaps with that of the SRF, and YY1 competes with the SRF for binding to these DNA elements. Overexpression of YY1 repressed serum-inducible and basal expression from the c-fos promoter and repressed basal expression from the skeletal alpha-actin promoter. YY1 also repressed expression from the individual SRE and MRE sequences upstream from a TATA element. Unlike that of YY1, SRF overexpression alone did not influence the transcriptional activity of the target sequence, but SRF overexpression could reverse YY1-mediated trans repression. These data suggest that YY1 and the SRF have antagonistic functions in vivo.

Surgical correction of hyperopia: a new experimental approach using X-incision and suture technique in rabbits

BACKGROUND

A new experimental surgical technique to correct hyperopia by steepening the central corneal curvature was performed on the eyes of rabbits.

METHODS

After X-shaped incisions at four quadrants of the paracentral cornea, four deep, transverse interrupted sutures were placed across the incisions and the knots were tightened to compress the corneal tissue in the direction of the suture. Twenty-three eyes of 12 albino rabbits were divided into group A (7 eyes) with a 4-millimeter diameter clear zone, group B (9 eyes) with a 6-millimeter diameter clear zone, and control group C, consisting of 7 contralateral eyes of group A without any incision or suture.

RESULTS

There was significant (p < .01) steepening of the central cornea as measured by the keratometer at postoperative 8 weeks in group A (+1.88 diopters) and group B (+1.68 D) compared with that of the control group C (-3.44 D). The difference in effect of hyperopic correction between groups of A and B was not statistically significant.

CONCLUSIONS

This procedure serves only as an experimental model of corneal response to incisions and sutures and is not for use in human corneas.

Differentiation between transmembrane helices and peripheral helices by the deconvolution of circular dichroism spectra of membrane proteins

The interpretation of the circular dichroism (CD) spectra of proteins to date requires additional secondary structural information of the proteins to be analyzed, such as X-ray or NMR data. Therefore, these methods are inappropriate for a CD database whose secondary structures are unknown, as in the case of the membrane proteins. The convex constraint analysis algorithm (Perczel, A., Hollósi, M., Tusnády, G., & Fasman, G. D., 1991, Protein Eng. 4, 669-679), on the other hand, operates only on a collection of spectral data to extract the common spectral components with their spectral weights. The linear combinations of these derived "pure" CD curves can reconstruct the original data set with great accuracy. For a membrane protein data set, the five-component spectra so obtained from the deconvolution consisted of two different types of alpha helices (the alpha helix in the soluble domain and the alpha T helix, for the transmembrane alpha helix), a beta-pleated sheet, a class C-like spectrum related to beta turns, and a spectrum correlated with the unordered conformation. The deconvoluted CD spectrum for the alpha T helix was characterized by a positive red-shifted band in the range 195-200 nm (+95,000 deg cm2 dmol-1), with the intensity of the negative band at 208 nm being slightly less negative than that of the 222-nm band (-50,000 and -60,000 deg cm2 dmol-1, respectively) in comparison with the regular alpha helix, with a positive band at 190 nm and two negative bands at 208 and 222 nm with magnitudes of +70,000, -30,000, and -30,000 deg cm2 dmol-1, respectively.

Inhibition of protein phosphatases blocks myogenesis by first altering MyoD binding activity

To examine the role of protein phosphatases in skeletal muscle differentiation, C2C12 myoblasts were treated with okadaic acid, a potent in vitro inhibitor of protein phosphatases 1 and 2A which regulate various cellular events in intact cells. We now show that okadaic acid treatment of the mouse myoblast C2C12 cell line reversibly altered the morphology of the cells and blocked differentiation. At a molecular level, it extinguished expression of the myogenic determination genes, MyoD1 and myogenin, but induced the expression of an inhibitor of differentiation, Id. Analysis of the MyoD1 promoter showed that inhibition of MyoD1 expression by okadaic acid occurs at the transcriptional level. These changes occur 10-20 h after okadaic acid treatment. However, within 1 h of treatment the ability of muscle extracts to support a specific MyoD-dependent gel mobility shift using a MyoD DNA binding site is lost. These data suggest that protein phosphatases play an important role during myogenic differentiation.