In situ expression of platelet-activating factor (PAF)-receptor gene in rat skin and effects of PAF on proliferation and differentiation of cultured human keratinocytes

Platelet-activating factor (PAF) is a potent lipid mediator that exhibits versatile biologic activities in many diverse systems by binding to a specific cell-surface receptor (PAFR). Although the production of PAF in cultured keratinocytes and fibroblasts has been reported, physiologic roles of this mediator in skin remain unclear. In this study, we examined in situ expression of PAFR gene in rat skin and the effects of PAF on the proliferation and differentiation of cultured human keratinocytes. In rat epidermis, PAFR mRNA expression was found from the basal cells to the granular cells, and strong signals were seen in the stratum spinosum. In cultured human keratinocytes, a 3.8 kb PAFR mRNA expression was demonstrated by northern blotting, and two distinct type transcripts driven by different promoters were detected by reverse transcriptase polymerase chain reaction analysis. Addition of PAF (30-100 nM) to cultured keratinocytes during a growth phase inhibited the proliferation. This effect was receptor dependent, because the inhibition was completely blocked by a PAFR antagonist, WEB 2086 (100 nM). On the other hand, whereas PAF (30-100 nM) alone did not affect the cornified envelope formation during the process of keratinocyte differentiation, WEB 2086 (30-300 nM) accelerated it in a concentration-dependent manner. Addition of PAF (100 nM) reversed the effect of WEB 2086, suggesting that WEB 2086 induced cornification by inhibiting PAF endogeneously produced by keratinocytes in an autocrine manner. Thus, we propose that PAF is an intrinsic regulator of keratinocyte during proliferation and differentiation.

Biological Species of Armillaria in Japan

Pairing tests with isolates of Armillaria in culture were used to identify species of Armillaria and their distribution throughout Japan. The existence of 10 intersterile groups of Armillaria was determined by pairing haploid single spore isolates obtained from 20 basidiocarps from a wide geographic distribution in Japan. Two to four haploid tester isolates from each intersterile group were then paired to biological and morphological species with haploid tester isolates from Europe and North America identified in previous studies. Japanese haploid tester isolates were then paired with 190 haploid or diploid isolates and compatibility reactions were used to identify these to species. Of the 10 intersterile groups identified in Japan, 7 were authenticated as A. gallica, A. nabsnona, A. ostoyae, A. cepistipes, A. mellea, A. sinapina, or A. tabescens. Three of the groups were not compatible with any of the tester species. The distribution and host relationships of the Japanese biological species are also discussed.

Supersensitivity of atherosclerotic artery to constrictor effect of cigarette smoke extract

OBJECTIVE

The aim of this study was to assess whether contractile response of arteries to aqueous component of cigarette smoke extract (CSE) may be modulated in atherosclerotic arteries.

METHODS

Thoracic aortas were isolated from control rabbits and from 1.5% cholesterol-fed rabbits, all of which had visible advanced atheromatous surface changes on the aortas. CSE was prepared by bubbling main stream of smoke from one cigarette with filter into 2 ml of phosphate-buffered saline. The thoracic aortic rings were suspended in organ chambers and tested with CSE (0.01-3.0 microliters/ml buffer in the organ chamber) after precontraction with 0.1 mumol/l of phenylephrine (PE).

RESULTS

The contractile response to CSE was significantly greater in atherosclerotic aortas than in control aortas (the maximal contraction expressed as % of the precontraction; control aortas 10.8 +/- 2.8%, atherosclerotic aortas 42.6 +/- 4.7%; P < 0.01). The magnitude of the precontractions by PE was not different between control and atherosclerotic aortas. Exogenous addition of superoxide dismutase (SOD) significantly attenuated the CSE-induced contraction in both control and atherosclerotic aortas and pretreatment of aortic rings with diethyldithiocarbamate to deplete of endogenous vascular CuZn-SOD activity potentiated the CSE-induced contraction in control aortas, while it had no significant effect in atherosclerotic aortas. The vascular SOD activity was significantly lower in atherosclerotic aortas than in control aortas ((U/mg protein): control aortas 38.2 +/- 3.3, atherosclerotic aortas 18.5 +/- 2.4; P < 0.01).

CONCLUSION

These results indicate that atherosclerotic arteries may be supersensitive to the constrictor effect of superoxide anion derived from CSE. The decrease in endogenous vascular SOD activity may partly contribute to the increased susceptibility to oxidative stress in atherosclerotic arteries.

Biphasic regulation of transcription factor nuclear factor-kappaB activity in human endothelial cells by lysophosphatidylcholine through protein kinase C-mediated pathway

Lysophosphatidylcholine (lysoPC), which is generated in oxidized LDL (Ox-LDL) and abundantly exists in atherosclerotic arterial walls, has been shown to alter various endothelial functions and induces several endothelial genes expressed in atherosclerotic arterial walls. Nuclear factor-kappa B (NF-kappaB), a pleiotropic transcription factor, plays an important role in regulation of expression of various genes implicated in atherosclerosis. We have previously reported that lysoPC transferred from Ox-LDL to endothelial surface membrane activates endothelial protein kinase C (PKC), leading to modulated endothelial functions. This study was aimed at determining whether lysoPC could modulate activity of transcription factors in cultured human umbilical vein endothelial cells (HUVECs) by using electrophoretic mobility shift assay. LysoPC was found to increase DNA-binding activity of NF-kappaB in HUVECs within 15 minutes, which peaked at 1 to 2 hours and subsequently declined to the baseline level at 6 hours. Lower concentrations (5 to 15 micromol/L) of lysoPC markedly increased NF-kappaB activity, but higher concentration (50 micromol/L) of lysoPC inhibited the activity. Phorbol 12-myristate 13-acetate, a potent activator of PKC, also augmented NF-kappaB activity in HUVECs, mimicking the effects of lysoPC; furthermore, calphostin C and chelerythrine chloride, specific PKC inhibitors, and alpha-tocopherol, a clinically potent PKC inhibitor, suppressed the lysoPC-induced NF-kappaB activation. These results indicate that lysoPC regulates NF-kappaB activity in a biphasic manner dependent on its concentrations and incubation time in human endothelial cells and the endothelial PKC activation may in part be involved in the lysoPC-induced NF-kappaB activation. Thus, the time course and the positive and negative biphasic regulatory actions of lysoPC on NF-kappaB activity in endothelial cells might exhibit a unique effect of lysoPC in arterial walls on the different stages of atherosclerosis.

[Binocular functions in amblyopia and strabismus]

Regarding the changing trends in the concept, definition, etiological classification, and criteria for diagnosis of amblyopia, we reviewed a total of 4,693 cases of amblyopia seen during the past 37 years. The amblyopia was divided into four types: strabismic, anisometropic, ametropic, and form vision deprivative. There was a definite trend for the incidence to decrease and for the diagnosis to be made during earlier age in recent years. Although favorable recovery of visual acuity is obtained after treatment of amblyopia and strabismus, there are difficulties in obtaining good binocular functions in early-onset amblyopia and strabismus. This feature was evaluated in regard to motion perception asymmetry (MPA) and binocular depth from motion (DFM). Many cases of early-onset amblyopia and strabismus showed no disparity stereopsis, or position stereopsis, in spite of the presence of DFM. The MPA appeared to be closely related to early-onset esotropia regardless of age, while it disappeared and motion perception became symmetric 4 to 5 months after birth in normal infants. The DFM seemed to play an important role in maintaining good motor alignment for several years after surgery. I developed a checkerboard pattern stimulator in 1978. This method proved to be useful in developing binocular functions and motor alignment by applying simultaneous bifoveolar stimulation and anti-suppression. Extensive exposure to the stimulation was essential for therapeutic success.

Complexes of apoA-1 with phosphatidylcholine suppress dysregulation of arterial tone by oxidized LDL

The aim of this study was to determine whether apolipoprotein A-1 (apoA-1) may suppress the vasomotor dysregulation by oxidized low-density lipoprotein (ox-LDL), which is known to be an atherogenic lipoprotein. The isolated porcine coronary arterial rings and the cultured endothelial cells from the porcine coronary arteries were exposed to ox-LDL in the presence or absence of complexes of apoA-1 with dimyristoylphosphatidylcholine (DMPC/apoA-1), apoA-1 alone, or DMPC alone. DMPC/apoA-1 but not apoA-1 alone or DMPC alone was found to suppress both impairment of endothelium-dependent arterial relaxation and vasocontraction caused by ox-LDL in the isolated porcine coronary arterial rings suspended in organ chambers. DMPC/apoA-1 absorbed lysophosphatidylcholine (LPC) from ox-LDL and decreased the transfer of LPC from ox-LDL to the surface membrane of the cultured endothelial cells, but apoA-1 alone and DMPC alone had no effect. High-density lipoprotein exerted the protective actions mimicking those observed in DMPC/apoA-1. Thus DMPC/apoA-1 decreased the transfer of LPC from ox-LDL to surface membrane by absorbing LPC, leading to the suppression of ox-LDL-induced dysregulation of endothelium-dependent arterial tone. Therefore, apoA-1 appears to require formation of the complexes with phospholipids to prevent the endothelial dysfunction caused by ox-LDL.

Solution structure of an extracellular domain containing the WSxWS motif of the granulocyte colony-stimulating factor receptor and its interaction with ligand

We have determined the NMR structure of a ligand-binding domain of the granulocyte colony-stimulating factor (G-CSF) receptor, containing the highly conserved WSxWS motif. The domain consists of seven beta-strands with the fibronectin type III-like topology seen in several cytokine receptors. Comparisons between the spectra of the 15N-labelled domain with and without G-CSF indicate that the major ligand-recognition site is on the FG loop just upstream of the WSxWS sequence, and not on the BC loop which is mainly used in the growth hormone system. The WSxWS residues are suggested to contribute to ligand-recognition and to the protein architecture of the G-CSF receptor.

Impairment of endothelium-dependent relaxation of rabbit aortas by cigarette smoke extract--role of free radicals and attenuation by captopril

The aim of this study was to examine the effects of the water soluble component of cigarette smoke extract (CSE) on endothelium-dependent relaxation (EDR) of isolated rabbit aortas. The incubation with CSE was found to inhibit EDR in a dose-dependent manner. Co-incubation of the aortic strips with superoxide dismutase (SOD), N-acetylcysteine, glutathione or dimethyl sulfoxide (DMSO), free radical scavengers, attenuated the CSE-induced inhibition of the arterial relaxation. Co-incubation of the strips with captopril (3 mM), an angiotensin converting enzyme inhibitor, also attenuated CSE-induced impairment of vasorelaxation. In parallel experiments using cultured human endothelial cells, CSE suppressed endothelial release of NOx, stable metabolites of nitric oxide (NO). SOD, DMSO and captopril attenuated the suppression of NO production by CSE in association with reduction of free radicals, superoxide anions and hydroxyl radicals, in CSE solution. Neither lactate dehydrogenase release from the cultured endothelial cells nor cell death estimated by trypan blue exclusion test was found after the incubation of the cultured endothelial cells with CSE. The results indicate that free radicals in CSE induce the impairment of EDR, which may be partly due to suppression of NO production and is not due to non-specific cytotoxicity by CSE. Captopril attenuates CSE-induced endothelial dysfunction partly through scavenging free radicals.

The product of the proto-oncogene c-cbl: a negative regulator of the Syk tyrosine kinase

Engagement of antigen and immunoglobulin receptors on hematopoietic cells is directly coupled to activation of nonreceptor protein tyrosine kinases (PTKs) that then phosphorylate critical intracellular substrates. In mast cells stimulated through the FcvarepsilonRI receptor, activation of several PTKs including Syk leads to degranulation and release of such mediators of the allergic response as histamine and serotonin. Regulation of Syk function occurred through interaction with the Cbl protein, itself a PTK substrate in this system. Overexpression of Cbl led to inhibition of Syk and suppression of serotonin release from mast cells, demonstrating its ability to inhibit a nonreceptor tyrosine kinase. Complex adaptor proteins such as Cbl can directly regulate the functions of the proteins they bind.

Study of the effect of atrial contraction on mitral prosthetic valve by high speed video camera

To clarify the effect of atrial contraction on the dynamic behavior of mitral prosthetic valves, a mechanical mock circulatory system has been developed. It is able to simulate the inflow characteristics during diastole. The disc motions of Björk-Shiley Monostrut (BSM29) and CarboMedics (CM29) valves (both with an annulus diameter of 29 mm) were measured and compared with a high speed video camera. After contraction of the artificial atrium (100 ms), there was a delay of 75 ms before the onset of the ventricular contraction. Mitral flow similar to physiological conditions could be achieved. The BSM29 was tested in the anterior position (a) and the posterior position (p). Under the condition of active atrial contraction (AC), we confirmed that the closing motion was initiated and the period during closing motion (PDCM) was prolonged (BSM29[a]: 22.4 +/- 3.4-->63 +/- 3.2; BSM29[p]: 71.2 +/- 38-->94.2 +/- 11; and CM29: 14 +/- 0.0-->28.4 +/- 2.3 [unit: ms]), the prolongation of the PDCM of the CM29 due to the AC being smaller than that of the BSM29. We also confirmed that the closing volume (CV) increased slightly (BSM29 [a]: 7.8 +/- 0.4-->8.5 +/- 0.8; BSM29[p]: 6.9 +/- 0.6-->7.0 +/- 0.5; and CM29: 3.6 +/- 0.6-->4.1 +/- 0.6 [unit: ml]). The CM29 had a shorter PDCM, less prolongation of the PDCM due to the AC, and less CV than the BSM29. Thus, we confirmed that the CM29 produced better response at valve closure than the BSM29.

Radiation dosage reduction in general dental practice using digital intraoral radiographic systems

This report describes the radiation dosage reduction possible in the general dental practice with two CCD (charge-coupled device)-based intraoral radiographic systems: the RVG-S (Trophy Radiologie, Vincennes, France) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). Radiation dosages (air-kerma; Gy) necessary for obtaining clinically acceptable images were measured at the cone tip using an ionization chamber type 660-1 (Nuclear Associates, Victoreen, Inc., Carle Place, New York, USA). When the RVG-S was used with an Oramatic 70 (Trophy Radiologie) X-ray generator, dosages at the cone tip ranged from 322 to 612 microGy. These corresponded to 40-60% of the dosages necessary when using Ektaspeed dental X-ray film (Eastman Kodak, Rochester, New York, USA) with a Heliodent 70 (Siemens, Erlangen, Germany) X-ray generator. At 60 kVp, the Sens-A-Ray reduced the dosage in the order of 30% compared with Ektaspeed dental X-ray film. Reduction in radiation dosage is one of the benefits of digital intraoral radiographic systems in general dental clinics. The RVG-S provides greater dose savings than does the Sens-A-Ray.

Cloning, expression and regulation of the human S14 gene

The rat S14 gene has been a useful model to study carbohydrate and triiodothyronine (T3) regulation of hepatic gene expression. To gain insight into the regulation and function of the S14 gene, we isolated the human S14 gene and studied its sequence, tissue specific expression, and transcriptional regulation by glucose and T3. The deduced amino acid sequence of the human S14 protein is 78% identical to that of the rat. Northern blot analysis showed that the S14-mRNA is a single species in human liver and is not present in human brain or HepG2 cells. Transfection studies in primary hepatocytes revealed that transcription of the human S14 gene is regulated by glucose and T3 in a similar manner to that of the rat gene. However, in HepG2 cells, T3 and glucose did not affect the transcription of the human S14 gene. These observations suggest that the S14 gene is highly conserved in mammals and is similarly regulated by carbohydrate and T3 in vivo. More importantly, the function of the human S14 gene may be critical in lipid metabolism in human liver as the rat S14 gene is in rodents.

Effects of ethyl alpha-D-glucoside on skin barrier disruption

Daily treatments of skin in hairless mice with concentrates of rice wine, Japanese traditional alcohol, lowered transepidermal water loss levels compared to the controls on the 3rd day after ultraviolet B (UVB) irradiation. These findings indicate that the concentrates of rice wine suppress the murine skin barrier disruption caused by UVB. Ethyl alpha-D-glucoside (alpha-ethylglucoside), one of the peculiar components in rice wine, showed the same effect, whereas beta-ethylglucoside had no effect. In order to clarify the functions of alpha-ethylglucoside on murine skin, we examined the effects of this compound on the expression of some phenotypes in human keratinocytes in vitro. As a result, alpha-ethylglucoside as well as beta-ethylglucoside enhanced cell proliferation weakly, and the formation of cornified envelopes and differentiated type keratin (K1) in keratinocytes was accelerated by alpha-ethylglucoside but not by beta-ethylglucoside. From the results, we conclude that alpha-ethylglucoside enhanced the differentiation of keratinocytes, which might be related to reduced barrier disruption by UVB.

Host range phenotype induced by mutations in the internal ribosomal entry site of poliovirus RNA

Most poliovirus strains infect only primates. The host range (HR) of poliovirus is thought to be primarily determined by a cell surface molecule that functions as poliovirus receptor (PVR), since it has been shown that transgenic mice are made poliovirus sensitive by introducing the human PVR gene into the genome. The relative levels of neurovirulence of polioviruses tested in these transgenic mice were shown to correlate well with the levels tested in monkeys (H. Horie et al., J. Virol. 68:681-688, 1994). Mutants of the virulent Mahoney strain of poliovirus have been generated by disruption of nucleotides 128 to 134, at stem-loop II within the 5' noncoding region, and four of these mutants multiplicated well in human HeLa cells but poorly in mouse TgSVA cells that had been established from the kidney of the poliovirus-sensitive transgenic mouse. Neurovirulence tests using the two animal models revealed that these mutants were strongly attenuated only in tests with the mouse model and were therefore HR mutants. The virus infection cycle in TgSVA cells was restricted by an internal ribosomal entry site (IRES)-dependent initiation process of translation. Viral protein synthesis and the associated block of cellular protein synthesis were not observed in TgSVA cells infected with three of four HR mutants and was evident at only a low level in the remaining mutant. The mutant RNAs were functional in a cell-free protein synthesis system from HeLa cells but not in those from TgSVA and mouse neuroblastoma NS20Y cells. These results suggest that host factor(s) affecting IRES-dependent translation of poliovirus differ between human and mouse cells and that the mutant IRES constructs detect species differences in such host factor(s). The IRES could potentially be a host range determinant for poliovirus infection.

Soluble thrombopoietin receptor (Mpl) and granulocyte colony-stimulating factor receptor directly stimulate proliferation of primitive hematopoietic progenitors of mice in synergy with steel factor or the ligand for Flt3/Flk2

In an effort to establish the specificity of the thrombopoietin (TPO) effects on murine multipotential progenitors, we tested the effects of soluble TPO receptor (sTPOR; sMpl) on multilineage colony formation that was supported by a combination of TPO and steel factor (SF). Surprisingly, sTPOR did not suppress colony formation from primitive progenitors. This led to the discovery that sTPOR synergizes with SF or Flt3/Flk2 ligand (FL) to support the formation of various types of hematopoietic colonies including multilineage colonies. The colonies supported by the combination of sTPOR and SF were capable of expressing both myeloid and B-lymphoid potentials. Studies using micromanipulation and serum-free culture showed that the effects of sTPOR and SF on the primitive progenitors are direct, not mediated by contaminating stromal cells, and not dependent on factors present in the serum. TPOR belongs to the cytokine receptor group that includes granulocyte colony-stimulating factor receptor (G-CSFR) and erythropoietin receptor (EPOR). Therefore, we tested the effects of sG-CSFR and sEPOR on primitive progenitors. sG-CSFR, but not sEPOR, was able to synergize with SF or FL in supporting the proliferation of primitive progenitors. The direct effects of the soluble receptors appear to be mediated through interactions with their respective membrane-bound receptors expressed on the primitive hematopoietic progenitors.

[Investigation of "anosmic zones" associated with nasal allergy]

Twenty-seven nasal allergy patients suffering from olfactory disturbance were evaluated in this study. The intravenous olfaction test yielded almost normal responses in 27 cases. The standard olfactory acuity test, however, showed that the mean thresholds of detection of each odor were almost the same, while the mean thresholds of recognition of odors A and E were higher than those of the other odors. Douek has reported selective olfactory loss in patients with vasomotor rhinitis including allergic rhinitis and proposed the concept of "anosmic zones". By modifying the definition of "anosmic zones" in order to use it for the results of T & T olfactometry, we identified 8 patients who exhibited anosmic zones among 27 subjects. These results were inconsistent with the proposed mechanism that nasal obstruction causes olfactory disturbance in patients suffering from nasal allergy. Therefore, the specific factors related to nasal allergy may influence olfaction. We speculate that the pathological changes in the olfactory mucosa may induce secondary abnormalities in olfactory transduction, particularly at the point of signal transduction in olfactory cells. Other possibilities to explain anosmic zones were also discussed.

Deficiencies of automatic endoscopic reprocessors: a method to achieve high-grade disinfection of endoscopes

BACKGROUND

We show that disinfection using the automatic endoscopic reprocessor is not complete and propose a method for high-grade disinfection of endoscopes.

METHODS

We used an automatic endoscopic reprocessor, Pyser System 83, and 2% glutaraldehyde. After each endoscopic procedure, the endoscopes were divided into three groups. Endoscopes in group A were washed only by the reprocessor. Group B endoscopes were washed by the reprocessor after the connectors were soaked in glutaraldehyde for 5 minutes. The channels, valves, connecting sections of group C endoscopes, and the connectors of the machine were sprayed with glutaraldehyde before machine-washing. Swabs were taken from all 13 parts of each endoscope and machine for microbiologic culture.

RESULTS

Six endoscopes were positive, cumulatively, for bacterial contamination in group A. Among group B endoscopes, one remained contaminated. No endoscope was positive in group C. The difference between group A and C was statistically significant (p < .05).

CONCLUSIONS

Machine washing by automatic endoscopic reprocessors may not achieve complete disinfection. Additional procedures are necessary. High-grade disinfection of the connectors is critical. Disinfection of the interface between the connectors is important.

Characterization of Cbl tyrosine phosphorylation and a Cbl-Syk complex in RBL-2H3 cells

Tyrosine phosphorylation of the Cbl protooncogene has been shown to occur after engagement of a number of different receptors on hematopoietic cells. However, the mechanisms by which these receptors induce Cbl tyrosine phosphorylation are poorly understood. Here we demonstrate that engagement of the high affinity IgE receptor (Fc epsilon R1) leads to the tyrosine phosphorylation of Cbl and analyze how this occurs. We show that at least part of Fc epsilon R1-induced Cbl tyrosine phosphorylation is mediated by the Syk tyrosine kinase, and that the Syk-dependent tyrosine phosphorylation of Cbl occurs mainly distal to the Cbl proline-rich region within the COOH-terminal 250 amino acids. Furthermore, we show by coprecipitation that Cbl is present in a complex with Syk before receptor engagement, that the proline-rich region of Cbl and a region of Syk comprised of the two SH2 domains and intradomain linker are required for formation of the complex, and that little or no tyrosine-phosphorylated Cbl is detected in complex with Syk. Overexpression of truncation mutants of Cbl capable of binding Syk has the effect of blocking tyrosine phosphorylation of endogenous Cbl. These results define a potentially important intramolecular interaction in mast cells and suggest a complex function for Cbl in intracellular signaling pathways.

Regulation of the association of p120cbl with Grb2 in Jurkat T cells

The c-cbl protooncogene product (p120(cbl)) is a known substrate of multiple tyrosine kinases. It is found in complexes with critical signal transduction molecules, including the linker protein Grb2. Here, we demonstrate using an immobilized Grb2-binding peptide that the Grb2-p120(cbl) complex dissociates in vivo following engagement of the T-cell antigen receptor in Jurkat T-cells. The early kinetics of this dissociation correlate with the known time course of tyrosine phosphorylation of p120(cbl) and other substrates. This dissociation persists in vivo even when p120(cbl) becomes dephosphorylated to basal levels. However, this decreased association is not observed in protein overlay assays on nitrocellulose membranes in which a Grb2 fusion protein is used to detect p120(cbl) from stimulated or unstimulated cells. These data suggest that the tyrosine phosphorylation of p120(cbl) does not completely account for the regulation of its association with Grb2. Additionally, we used truncation mutations of p120(cbl) to map the p120(cbl)-Grb2 interaction to amino acids 481-528 of p120(cbl); this interaction is stronger in longer constructs that include additional proline-rich motifs. The in vivo regulation of the Grb2-p120(cbl) complex further supports the idea of a significant role for p120(cbl) in receptor-mediated signaling pathways.