Endothelial Insulin Resistance Exacerbates Experimental Periodontitis

Epidemiological studies suggest that the severity of periodontitis is higher in people with diabetes than in healthy individuals. Insulin resistance might play a crucial role in the pathogenesis of multiple diabetic complications and is reportedly induced in the gingiva of rodents with type 2 diabetes; however, the molecular mechanisms underlying the pathogenesis of diabetes-related periodontitis remain unclear. Therefore, we aimed to investigate whether endothelial insulin resistance in the gingiva may contribute to the pathogenesis of periodontitis as well as elucidate its underlying molecular mechanisms. We demonstrated that insulin treatment downregulated lipopolysaccharide (LPS)-induced or tumor necrosis factor α (TNFα)-induced VCAM1 expression in endothelial cells (ECs) via the PI3K/Akt activating pathway, resulting in reduced cellular adhesion between ECs and leukocytes. Hyperglycemia-induced selective insulin resistance in ECs diminished the effect of insulin on LPS- or TNFα-stimulated VCAM1 expression. Vascular endothelial cell-specific insulin receptor knockout (VEIRKO) mice exhibited selective inhibition of the PI3K/Akt pathway in the gingiva and advanced experimental periodontitis-induced alveolar bone loss via upregulation of Vcam1, Tnfα, Mcp-1, Rankl, and neutrophil migration into the gingiva compared with that in the wild-type (WT) mice despite being free from diabetes. We also observed that insulin-mediated activation of FoxO1, a downstream target of Akt, was suppressed in the gingiva of VEIRKO and high-fat diet (HFD)-fed mice, hyperglycemia-treated ECs, and primary ECs from VEIRKO. Further analysis using ECs transfected with intact and mutated FoxO1, with mutations at 3 insulin-mediated phosphorylation sites (T24A, S256D, S316A), suggested that insulin-mediated regulation of VCAM1 expression and cellular adhesion of ECs with leukocytes was attenuated by mutated FoxO1 overexpression. These results suggest that insulin resistance in ECs may contribute to the progression of periodontitis via dysregulated VCAM1 expression and cellular adhesion with leukocytes, resulting from reduced activation of the PI3K/Akt/FoxO1 axis.

Epicatechin downregulates adipose tissue CCL19 expression and thereby ameliorates diet-induced obesity and insulin resistance

BACKGROUND AND AIMS

Epicatechin (EC) intake has been suggested to be beneficial for the prevention of cardiovascular disorders, and it is well known that adipose tissue inflammation is one of the major risk factors for coronary heart diseases. The purpose of the present study was to determine the in vitro and in vivo effects of EC on adipose tissue inflammation and obesity.

METHODS AND RESULTS

DNA microarray analysis was performed to evaluate the effects of EC on gene expression in adipocytes co-cultured with bacterial endotoxin-stimulated macrophages. To determine the in vivo effects of the catechin, C57BL/6 mice were fed either a high-fat diet (HFD) or HFD combined with EC, and metabolic changes were observed EC suppressed the expression of many inflammatory genes in the adipocytes co-cultured with endotoxin-stimulated macrophages. Specifically, EC markedly suppressed chemokine (CC motif) ligand 19 (CCL19) expression. The target cell of EC appeared to macrophages. The in vivo study indicated that mice fed the EC-supplemented HFD were protected from diet-induced obesity and insulin resistance. Accordingly, the expression levels of genes associated with inflammation in adipose tissue and in the liver were downregulated in this group of mice.

CONCLUSIONS

EC exerts beneficial effects for the prevention of adipose tissue inflammation and insulin resistance. Since we previously reported that mice deficient in the CCL19 receptor were protected from diet-induced obesity and insulin resistance, it can be concluded that the beneficial effects of EC could be mediated, at least in part, by marked suppression of CCL19 expression.

Gate-Tunable Spin-Charge Conversion and the Role of Spin-Orbit Interaction in Graphene

The small spin-orbit interaction of carbon atoms in graphene promises a long spin diffusion length and the potential to create a spin field-effect transistor. However, for this reason, graphene was largely overlooked as a possible spin-charge conversion material. We report electric gate tuning of the spin-charge conversion voltage signal in single-layer graphene. Using spin pumping from an yttrium iron garnet ferrimagnetic insulator and ionic liquid top gate, we determined that the inverse spin Hall effect is the dominant spin-charge conversion mechanism in single-layer graphene. From the gate dependence of the electromotive force we showed the dominance of the intrinsic over Rashba spin-orbit interaction, a long-standing question in graphene research.

Experimental Demonstration of Room-Temperature Spin Transport in n-Type Germanium Epilayers

We report an experimental demonstration of room-temperature spin transport in n-type Ge epilayers grown on a Si(001) substrate. By utilizing spin pumping under ferromagnetic resonance, which inherently endows a spin battery function for semiconductors connected with a ferromagnet, a pure spin current is generated in the n-Ge at room temperature. The pure spin current is detected by using the inverse spin-Hall effect of either a Pt or Pd electrode on n-Ge. From a theoretical model that includes a geometrical contribution, the spin diffusion length in n-Ge at room temperature is estimated to be 660 nm. Moreover, the spin relaxation time decreases with increasing temperature, in agreement with a recently proposed theory of donor-driven spin relaxation in multivalley semiconductors.

Large voltage-induced magnetic anisotropy change in a few atomic layers of iron

In the field of spintronics, researchers have manipulated magnetization using spin-polarized currents. Another option is to use a voltage-induced symmetry change in a ferromagnetic material to cause changes in magnetization or in magnetic anisotropy. However, a significant improvement in efficiency is needed before this approach can be used in memory devices with ultralow power consumption. Here, we show that a relatively small electric field (less than 100 mV nm(-1)) can cause a large change (approximately 40%) in the magnetic anisotropy of a bcc Fe(001)/MgO(001) junction. The effect is tentatively attributed to the change in the relative occupation of 3d orbitals of Fe atoms adjacent to the MgO barrier. Simulations confirm that voltage-controlled magnetization switching in magnetic tunnel junctions is possible using the anisotropy change demonstrated here, which could be of use in the development of low-power logic devices and non-volatile memory cells.

Real-space observation of current-driven domain wall motion in submicron magnetic wires

We report direct observation of current-driven magnetic domain wall (DW) displacement by using a well-defined single DW in a microfabricated magnetic wire with submicron width. Magnetic force microscopy visualizes that a single DW introduced in a wire is displaced back and forth by positive and negative pulsed current, respectively. The direct observation gives quantitative information on the DW displacement as a function of the intensity and the duration of the pulsed current. The result is discussed in terms of the spin-transfer mechanism.

Discrete change of spin-density-wave modulation in Cr(100)/Sn multilayers as a function of Cr layer thickness

Magnetic structures of epitaxial Cr(001)/Sn multilayers, where monatomic Sn layers are periodically embedded in a Cr(001) film, were studied using neutron diffraction and Mössbauer spectroscopy. It was found that spin-density-wave (SDW) antiferromagnetic structures with the modulation along the perpendicular direction to the film plane are stabilized at low temperatures. The wavelength of the SDW discretely changes as a function of the superlattice period. The enhanced magnetic moments of Cr at the Cr/Sn interfaces are thought to pin the antimode of the SDW modulation at the interface, resulting in the SDW with the modulation harmonic to the superlattice period.

Differentiation of Fusobacterium necrophorum subspecies from bovine pathological lesions by RAPD-PCR

Nineteen strains from bovine abscesses identified as Fusobacterium necrophorum by the VPI method were examined by other methods. The API 20A test kit characterized all 19 strains as F. necrophorum. Seven of the strains had haemagglutinating activity and were classified as F. necrophorum subspecies necrophorum, and the remaining, 12 nonhaemagglutinating strains, were classified as F. necrophorum subspecies funduliforme. We used RAPD-PCR with a 10-mer oligonucleotide primer, W1L-2, to confirm this differentiation of the two subspecies. These results suggest that random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) with a suitable primer can be used as a new tool for the differentiation of F. necrophorum subspecies isolated from bovine pathological lesions.

Isolation of Pasteurella multocida during an outbreak of infectious septicemia in Japanese quail (Coturnix coturnix japonica)

In May 1994, about fifty Japanese quails out of ninety being bred for experimental purposes at Miyazaki University died of acute septicemia within a few days. At autopsy, there were no gross pathological lesions, however, severe bacteremia was observed in all cases. Bacterial examination revealed the presence of Pasteurella multocida in blood and several organs in pure culture and they were of Carter's capsular type A, Heddleston's type 3-4 and Namioka's type O-8-9. The LD50 of bacteria in quails and mice were 4.3 x 10(4) cfu and 3.9 x 10(2) cfu, respectively. All of the three chickens experimentally infected with 4 x 10(4) of the isolate died within 20 hr after the infection and several bacteria were recovered from their blood and organs. This, to our knowledge, is the first report on an outbreak of fowl cholera in Japanese quails in Japan.

Lymphoproliferative responses in pigs infected with Mycobacterium avium

Naturally infected cases of swine mycobacteriosis were divided into two groups, localized infection (LI) and disseminated infection (DI). Lymphoproliferative response (LPR) was then examined to estimate their immunological states. Both control and LI groups showed strong response to Concanavalin A (Con A) and phytohemagglutinin (PHA) in the LPR, and lymphocytes recovered from the LI responded well to purified protein derived from M. avium (PPD). On the other hand, the DI group showed weak response to both Con A and PHA, despite their strong response to PPD stimulation. These data suggest that the low LPR to Con A and PHA observed in the DI groups was probably not due to the general unresponsiveness of T-cells.

[Detection of Emericella nidulans from bedding materials in horse breeding environment and its significance as a causative agent of guttural pouch mycosis in horses]

Sixty-six new and used samples of horse bedding materials: 60 rice straws, 2 wheat straws, 2 timothy hays and 2 wood chips, were collected from horse breeding stables of 33 farms in Japan and examined for the presence of Emericella nidulans (E. nidulans; anam. Aspergillus nidulans). The incidence of E. nidulans in the bedding materials was 75.8% and there was no significant difference in detection of the fungus between the new and used materials (25 out of the 33 samples, respectively). The growth of E. nidulans isolated in sterilized rice straw culture was accelerated by the addition of water up to about Aw 0.94, which as determined to be the most favorable moisture content. The addition of 0.3% urea solution onto the sterilized rice straw culture also appeared to very effectively enhance its conidial and ascocarp formation. A significant influence of urea on conidial and ascocarp formation of E. nidulans isolates was confirmed by their cultures on a synthetic medium which had urea as the sole nitrogen. These results suggest that severe contamination of E. nidulans on new bedding materials can be hazardous and its proliferation can readily occur at the stable due to the enhancing effect of urine. This analysis is meaningful to elucidate a reservoir of E. nidulans as the causative agent of guttural pouch mycosis in horses.

Magnetic vortex core observation in circular dots of permalloy

Spin structures of nanoscale magnetic dots are the subject of increasing scientific effort, as the confinement of spins imposed by the geometrical restrictions makes these structures comparable to some internal characteristic length scales of the magnet. For a vortex (a ferromagnetic dot with a curling magnetic structure), a spot of perpendicular magnetization has been theoretically predicted to exist at the center of the vortex. Experimental evidence for this magnetization spot is provided by magnetic force microscopy imaging of circular dots of permalloy (Ni(80)Fe(20)) 0.3 to 1 micrometer in diameter and 50 nanometers thick.

Endotoxin-triggered haematological interactions in Fusobacterium necrophorum infections

The haematological mechanisms in the course of liver abscess formation were evaluated. They were examined by employing viable cells of Fusobacterium necrophorum subsp. necrophorum and Fusobacterium necrophorum subsp. funduliforme in comparison with their endotoxins. Whole cell infection with F.n. necrophorum led to neutrophilia and to a concomitant monocytosis in parallel with those responses induced by the in vivo injection of its endotoxin. Viable infection with F.n. funduliforme was characterized by a sustained endotoxin-related monocytosis against neutropenia. The stimulatory impact of endotoxin on monocytes when released from a viable F.n. funduliforme infection suggested an inherently peculiar mechanism which differed from the induction of both neutrophilia and monocytosis when F.n. funduliforme endotoxin was administered alone. The neutrophilic inducing capacity of the F.n. necrophorum endotoxin was equally illustrated by its positive chemotactic effect on polymorphonuclear neutrophils in vitro. The data presented here emphasize the virulence of F.n. necrophorum viewed in reference to changes in leucocyte trafficking and as complemented by a relatively high endotoxin content.

Reduction of magnetic moments in very thin Cr layers of Fe/Cr multilayers: evidence from 119Sn Mössbauer spectroscopy

Fe/Cr multilayers with monatomic Sn layers embedded in the Cr layers were grown epitaxially on MgO(001) substrates, and the magnetic hyperfine field at the 119Sn nuclear sites was examined using Mössbauer spectroscopy. It was found that nonzero hyperfine field is induced at the Sn sites at room temperature and that the value reduces drastically from 10 to 2 T when the Cr layer thickness decreases from 80 to 10 A. The result indicates that the Cr layers are magnetically ordered even when the thickness is very small and that the magnetic moments of Cr become smaller as the Cr layer thickness decreases.

Chemical composition of endotoxins produced by Fusobacterium necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme

The endotoxins from two recently-classified subspecies of Fusobacterium, namely F. necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme, were compared. Chemical analysis of the isolated endotoxins revealed that they were clearly different. Distinct levels of polysaccharides were demonstrated. The endotoxins isolated were devoid of heptose and 3-deoxy-D-manno-octulosonate (KDO). The endotoxins of F. n. necrophorum and F. n. funduliforme contained lipid A in a ratio of 4:1 which may account for the variations in their virulence.

Propagation of a magnetic domain wall in a submicrometer magnetic wire

The motion of a magnetic domain wall in a submicrometer magnetic wire was detected by use of the giant magnetoresistance effect. Magnetization reversal in a submicrometer magnetic wire takes place by the propagation of a magnetic domain wall, which can be treated as a "particle." The propagation velocity of the magnetic domain wall was determined as a function of the applied magnetic field.

The erythrocyte receptor for Fusobacterium necrophorum hemolysin: phosphatidylcholine as a possible candidate

An attempt was made to determine the receptor for the hemolysin of Fusobacterium necrophorum using horse erythrocyte or its membranes as target. The spectrum of erythrocyte sensitivity has indicated that horse, dog and mouse erythrocytes are highly sensitive whereas cattle, sheep, goat and chicken red blood cells are insensitive to this hemolysin. A high correlation between sensitivity and phosphatidylcholine content of the erythrocyte membranes was noted. Binding of hemolysin to horse erythrocyte membranes was reduced significantly by prior treatment of membranes with phospholipase A2 but not with phospholipase C. Pretreatment of erythrocyte membranes with pronase, proteinase K, trypsin or neuraminidase did not alter binding of hemolysin to the membranes, suggesting that protein or sialyl residues are not involved as receptors. Gas liquid chromatography analysis showed that the fatty acid profile from hydrolysis of bovine liver phosphatidylcholine by hemolysin and phospholipase A2 were similar. In conclusion, this report presents evidence that phosphatidylcholine may be acting as a possible receptor for the hemolysin of F. necrophorum.

The effect of Bcg gene on antigen presentation of spleen adherent cells and peritoneal macrophages from Mycobacterium bovis BCG-infected Bcg(s) and Bcg(r) mice

To determine the role of the Bcg gene in the resistance and susceptibility of BCG-infected C57BL/6 (Bcg(s)) and its Bcg(r) congenic mice, the antigen presenting ability of spleen adherent cells and peritoneal macrophages, delayed type hypersensitivity (DTH) and lymphocyte blastogenic responses were investigated. The results obtained indicate that the DTH and lymphocyte blastogenic responses in Bcg(r) congenic mice were higher than in the Bcg(s) mice. Stimulation of spleen adherent cells with live Mycobacterium bovis BCG or PPD-BCG resulted in a higher antigen presenting ability in Bcg(r) than in Bcg(s) mice. However, comparatively low responses were associated with M. avium stimulation, with those in Bcg(r) being higher than in Bcg(s). I-A expression was also comparatively higher in Bcg(r) than in Bcg(s) mice. This study demonstrates that the Bcg gene seems to exhibit some effect on the antigen presenting ability of macrophages in immune responses of the congenic mice.

Interactions between Fusobacterium necrophorum hemolysin, erythrocytes and erythrocyte membranes

The interactions between the hemolysin of Fusobacterium necrophorum subsp. necrophorum, erythrocytes and erythrocyte membranes were studied as an attempt to determine the initial characteristics leading to hemolysis. The spectrum of erythrocyte sensitivity indicated that horse, dog and mouse erythrocytes were highly sensitive whereas those of cattle, sheep, goat and chicken were insensitive to the hemolysin. Binding of hemolysin to horse and dog erythrocytes or their ghosts was more pronounced than to those of cattle and sheep as detected by a decrease of hemolytic activity from hemolysin preparations. The kinetics of hemolysis revealed that lysis is preceded by a prelytic phase characterized by binding of hemolysin to erythrocytes. Treatment of horse erythrocytes with hemolysin at various temperatures prior to incubation at 37 degrees C also revealed that this binding prelytic phase is temperature independent. This was followed by a temperature dependent lytic stage since erythrocytes pretreated with hemolysin and incubated at 4 degrees C showed no hemolysis. An inverse relation was found between erythrocyte concentration and hemolytic activity suggesting a multiple-hit mechanism of hemolysis.

The effects of physical and chemical agents on the secretion and stability of a Fusobacterium necrophorum hemolysin

The effect of various agents as enhancers or inhibitors of hemolysin secretion by Fusobacterium necrophorum was investigated. The hemolysin secreted in phosphate buffered saline (PBS) alone was inactivated shortly after secretion. Tween-80 or albumin preserved the hemolytic activity in PBS in which cultures of F. necrophorum had been suspended. Hemoglobin was found to enhance hemolysin secretion. However, higher concentrations diminished secretion. Chloramphenicol, an inhibitor of protein synthesis, exhibited no effect on the hemolytic activity. However, the addition of sodium azide, an energy metabolic inhibitor, significantly reduced the hemolytic activity. Lower temperatures and pH above 9 and below 6 all yielded a low hemolytic activity. Cells suspended in Tween-80 prior to sonication yielded a substantial amount of extracellular hemolytic activity with low intracellular activity detected. However, cells suspended in PBS alone yielded a low extracellular activity but rather a high intracellular activity. The same spectrum of red blood cells of different species were found to be sensitive to both the extracellular and intracellular hemolysins.

Stability and stabilization of Fusobacterium necrophorum hemolysin

The stability and stabilization of the hemolytic activity of Fusobacterium necrophorum subsp. necrophorum and Fusobacterium necrophorum subsp. funduliforme were monitored over a period of four weeks using culture supernatants. The hemolytic activity was completely lost after one week at room temperature and 37 degrees C. After a two-week storage at 4 degrees C and -80 degrees C only trace activity was detected with -80 degrees C being the better of the two conditions. The addition of cysteine monohydrochloride, bovine serum albumin or Tween 80 as stabilizers, however, led to the detection of a considerable amount of the hemolytic activity in the sample stored at 4 degrees C and - 80 degrees C throughout the period investigated. The hemolytic activity appeared to be more stable in the presence of Tween 80 at -80 degrees C. Cysteine monohydrochloride was found to crystallize at - 80 degrees C and was therefore ineffective as a stabilizer at this temperature. Hemoglobin was also ineffective as a stabilizer.

Establishment of Bcgr congenic mice and their susceptibility/resistance to mycobacterial infection

Bcg congenic mice were developed by using C57BL/6 and DBA/2 strains of mice as progenitors. They were obtained by introgressively backcrossing the Bcgr marker of DBA/2 onto C57BL/6. After twenty successive backcrossings, the heterozygous resistant mice were mated with each other to obtain homozygous mice as the Bcgr congenic mice. The results of immunogenic and genetic markers coupled with those of an mixed lymphocyte reaction, all confirmed that the newly developed mice were highly congenic. These congenic mice were found to be resistant to in vivo infections by Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium bovis BCG.

Comparison of haemolytic activity between Fusobacterium necrophorum subsp. necrophorum and Fusobacterium necrophorum subsp. funduliforme in vitro and in vivo

Haemolytic activity of two subspecies of Fusobacterium necrophorum was compared in vitro and in vivo. F. necrophorum subsp. necrophorum (Fnn) showed a stronger activity than F. necrophorum subsp. funduliforme (Fnf) in vitro. Haemolytic activity of Fnn and Fnf was 57.97%+/-1.90 and 17.33%+/-1.44, respectively, compared to complete haemolysis by distilled water. In the mice injected with Fnn, haemolysin was detected in the liver at a titre of from 1 : 16 to 1 : 128, and Fnn was recovered from all mice at a viable bacterial count of 10(5) to 10(6) cells per gram liver tissue. In the mice injected with Fnf, haemolysin titre was <1 : 2 to 1 : 32. No liver abscess was formed. The viable count of recovered bacteria was 10(3) to 10(5) cells per gram, except for two mice in which no Fnf was detected. The results suggest that haemolysin might be a virulence factor in this species.

Immune responsiveness in Mycobacterium avium-infected mice: changes in the proportion of T cell subsets and antibody production during the course of infection

The C57Bl/6 susceptible (Bcgs) and its resistant (Bcgr) congenic mouse, previously developed by retrogressive backcrossing, were infected with 1 x 10(6) colony-forming units (CFU) of Mycobacterium avium and bacterial growth and their immune responses during the early and prolonged periods of infection were examined. There was a high proliferation in the liver and spleen of Bcgs mice, whereas no proliferation was observed in the Bcgr mice. Similarly, the sizes and weights of these organs were much higher than those of their Bcgr counterparts. The size and number of granulomas in Bcgs were also found to be higher than those of Bcgr. The CD3+ and CD4+ subsets increased dramatically in both mice during the early stage of infection. However, in the later phase of the infection, these populations decreased dramatically in Bcgs mice, but not in Bcgr mice, resulting in a depression in cell-mediated immune responses. No significant decrease in cell-mediated immune responses was observed in Bcgr mice even after prolonged infection. ELISA was performed to determine the antibody levels in both mice, and it was found that serum IgG and IgM levels in Bcgs were comparatively higher than those in Bcgr mice throughout the period of infection. The Bcg gene therefore may have an important role in the maintenance of resistance not only in the early phase but also in the later phase of Myco. avium infection.

Granulomatous epididymitis related to Rhodotorula glutinis infection in a dog

A 4-year-old, male Great Dane dog developed severe swelling of the scrotum on 9 December 1991, and the testes and epididymides were removed surgically on 12 December 1992. The cut surface of the epididymides consisted of hard connective tissue and several small abcesses with slight hemorrhage. Histopathologically, the seminiferous tubules in the testes had only a few spermatogenic cells, but Sertoli cells were well preserved. Both epididymides consisted entirely of a proliferation of fibrous connective tissue, and only a few ducts deferens containing cell debris, neutrophils, and macrophages in the lumina were present. In all lesions of the epididymides, the macrophages contained periodic acid-Schiff- and Grocott's silver-positive round granules, 5-8 microns in diameter. Microbiologically, smooth salmon-pink colonies consisting of ovoidal yeast, about 10 microns in diameter, were isolated from the samples of epididymides but not from those of the testes. The isolated yeast had microbiological characteristics of Rhodotorula glutinis. From these observations, we diagnosed the present case as granulomatous epididymitis due to Rhodotorula infection.

Detection of the cellular membrane proteins on human T cell leukemia virus type I

The presence of cellular membrane proteins on human T cell leukemia virus type I (HTLV-I) was examined. ICAM-1 and MHC-IIDR, which were highly expressed on MT-2 cells but not on MOLT-4#8 cells, became detectable on HTLV-I-binding MOLT-4#8 cells. Furthermore, a batch of other cellular molecules including LFA-1, ICAM-1, LFA-3, MHC-I, MHC-IIDR, and CD4 became detectable on HTLV-I-binding BW5147 cells, a mouse T-lymphoma cell line, which were able to adsorb HTLV-I. The detectable levels of these molecules were correlated with those expressed on MT-2 cells. The detectable levels of the cellular proteins of human decreased by pretreatment of HTLV-I with sera from HTLV-I seropositive individuals but not from seronegatives. These results indicate that HTLV-I envelope carries cellular membrane proteins derived from the host cell.

Studies on the factors affecting the hemolytic activity of Fusobacterium necrophorum

The in vitro activity of the hemolysin of Fusobacterium necrophorum was determined using the hemolysis of horse erythrocytes as an assay. The effects of medium composition and pH on hemolysin production were investigated. Calf serum and casitone stimulated a comparatively higher hemolytic activity in F. necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme, respectively. However, sugars, such as glucose, galactose and fructose were inhibitors of hemolytic activity. The spectrum of erythrocyte sensitivity to the hemolysin indicated that horse and quail erythrocytes were more sensitive to the hemolysin of both F. necrophorum subsp. necrophorum and subsp. funduliforme, than were cat, dog, rabbit, pigeon and human erythrocytes. Cat erythrocytes were however insensitive to the hemolysin of subsp. funduliforme. Cattle, sheep and chicken erythrocytes were insensitive to the hemolysin of the two subspecies. Medium pH near neutral were more effective in enhancing hemolytic activity, and hemolytic activity was positively correlated with growth. In general, F. necrophorum subsp. necrophorum was more hemolytic than subsp. funduliforme.

Exposure of p19 matrix protein of human T-cell leukemia virus type I (HTLV-I) on the surface of MOLT-4#8 cells after virus adsorption

The p19 matrix (MA) protein of human T-cell leukemia virus type I (HTLV-I) was exposed on the surface of MOLT-4#8 cells in the very early step of the virus infection. Transfer of the virus-binding MOLT-4#8 cells from 4 degrees C to 37 degrees C resulted in increased detection of the viral gp46 and p19 MA protein on the cells, which was, however, inhibited by 4 degrees C or cytochalasin B treatment. These data showed that increased temperature and fluidity of the cell membrane were required for the increased detection of gp46 and p19 after viral adsorption. On the other hand, exposure of the p19 MA protein was not observed on the virus-treated U937 cells although gp46 was detected. This was not due to inefficient binding of the HTLV-I to the U937 cells, since the methanol-fixed cells were p19 MA protein-positive. MOLT-4#8 cells induced marked cell fusion when co-cultured with MT-2 cells, but U937 cells induced no fusion. All of these results indicated that these two cell lines differed in the property of plasma membrane in terms of degradation of HTLV-I envelope after viral adsorption. Uncoating of the HTLV-I might occur on the plasma membrane, especially on MOLT-4#8 cells.

Simple assay system for detecting human T cell leukemia virus type I-binding cells and its application in titrating binding inhibitory antibodies

BACKGROUND

A simple and rapid assay system for the detection of human T cell leukemia virus type I (HTLV-I) binding cells was developed to assess the virus specific receptor and titrate the antibodies to block the virus binding.

EXPERIMENTAL DESIGN

Cells (5 x 10(5)) were incubated with 100 microliters of the concentrated HTLV-I at 37 degrees C for 1 hour. After washing, the cells were reacted with anti-HTLV-I envelope monoclonal antibody (rat) for 30 minutes on ice and then stained with fluorescein-isothiocyanate-conjugated anti-rat immunoglobulin. The stained samples were analyzed on FACScan. Antibody-titration of the virus-binding inhibition was carried out by pretreatment of the virus with serially diluted sera.

RESULTS

The specificity of the virus-binding was shown by dose-response relationship, kinetics of the binding, and temperature dependency. HTLV-I was absorbed onto a wide range of human cell lines and peripheral blood lymphocytes at various levels. Antibodies to inhibit the virus-binding were also quantitatively detected in sera from HTLV-I infected individuals, including asymptomatic carriers and patients with adult T cell leukemia or HTLV-I-associated myelopathy, but not from healthy seronegative controls.

CONCLUSIONS

This assay system would be useful in screening the virus-specific receptor and the neutralizing antibodies to HTLV-I. Thus, the assay could be applied to further studies on HTLV-I-related diseases.

Comparison of extracellular enzymes of Fusobacterium necrophorum subsp. necrophorum and Fusobacterium necrophorum subsp. funduliforme

A total of 10 strains each of Fusobacterium necrophorum subsp. necrophorum and Fusobacterium necrophorum subsp. funduliforme were tested for the production of 13 extracellular enzymes. DNase, alkaline phosphatase, and lipase were predominantly associated with all the strains of F. necrophorum subsp. necrophorum, with DNase not detected in any of the strains of F. necrophorum subsp. funduliforme. In addition, the strains of F. necrophorum subsp. necrophorum were generally more hemolytic than those of F. necrophorum subsp. funduliforme. Lecithinase, beta-lactamase, elastase, hyaluronidase, chondroitin sulfatase, and coagulase were not detected in any of the strains. DNase may be used to differentiate between the two subspecies.

Platelet abnormalities in a dog suffering from gangrenous mastitis by Staphylococcus aureus infection

Severe gangrenous mastitis due to Staphylococcus aureus infection was diagnosed in a 7 year-old intact female beagle which was presented with swelling of mammary glands after dystocia. Leukocytosis (25,200-48,600/microliters), decreased platelets (107,000-179,000/microliters), and abnormal platelet pattern continued during the critical condition. Consistent with platelet pattern, large platelets were observed in the blood smear. The number of leukocytes and platelets rapidly returned to normal during treatment, and the platelet pattern was also restored. The number and pattern of platelet may provide a clue for the evaluation of the clinical condition and/or severity of the lesions in the dog with mastitis.

Aggregation of bovine platelets by Fusobacterium necrophorum

Washed cell suspensions of biovar A strains of Fusobacterium necrophorum aggregated cattle platelets, but similar suspensions of biovar B strains did not. Platelets were also aggregated by heat-treated bacterial cells or the lipopolysaccharide of biovar A. No platelet aggregation occurred in the presence of the cell-free culture supernatant of biovar A and of all samples prepared from biovar B. Scanning electron microscopy revealed that aggregated platelets were not damaged. Platelet aggregation was inhibited by EDTA, aspirin and quinacrine, and lag time was retarded by these inhibitors, indicating the reaction was a Ca(2+)-dependent, cyclo-oxygenase sensitive event. Platelet aggregation may be a virulence marker, probably mediated by the lipopolysaccharide of F. necrophorum biovar A strains.

Biological characterization of human immunodeficiency virus type 1 and type 2 mutants in human peripheral blood mononuclear cells

Mutants of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), which have been shown to be infectious in established cell lines, were tested for ability to replicate and induce syncytium formation in human peripheral blood mononuclear cells (PBMC). The vpu mutant of HIV-1 showed depressed kinetics of replication in an established T cell line, as reported previously, but in PBMC, its replication was similar to that of the wild type virus. The vpx gene of HIV-2 was required for efficient virus propagation in PBMC, but not in an established T cell line, as previously reported. However, the growth rates of the vpx mutant in PBMC preparations from two individuals were different. The results of experiments on infection of PBMC with the vif and vpr mutants of HIV-1 and HIV-2 were essentially consistent with previous results of infection of established T cell lines. No negative effect of the nef gene products of HIV-1 and HIV-2 was observed. The abilities of the wild type virus and the mutants of HIV-1 to induce syncytium formation in both PBMC and established cell lines were similar. In contrast, neither the wild type nor any of the mutants of HIV-2 induced syncytium formation in PBMC. These results suggest that the functions of some genes can be detected only in mixed populations or primary cells such as PBMC. Studies on the roles of these genes in PBMC may provide a better understanding of their functions in vivo.

Proposal of two subspecies of Fusobacterium necrophorum (Flügge) Moore and Holdeman: Fusobacterium necrophorum subsp. necrophorum subsp. nov., nom. rev. (ex Flügge 1886), and Fusobacterium necrophorum subsp. funduliforme subsp. nov., nom. rev. (ex Hallé 1898)

The biological and biochemical properties, DNA base compositions, and levels of DNA-DNA homology of two biovars of Fusobacterium necrophorum were examined. Some differences were found between the two biovars in biological and biochemical properties. The G + C contents of DNAs from biovar A strains VPI 2891T (T = type strain), NCTC 10576, N167, Fn47, and Fn43, were 32, 30, 29, 28, and 31 mol%, respectively. The G + C contents of DNAs from biovar B strains Fn524T, 606, Fn49, Fn45, and 1260 were 30, 31, 27, 31, and 30 mol%, respectively. Labeled DNA from biovar A strain VPI 2891T exhibited 100 to 80% relatedness to DNAs from biovar A strains and 59 to 51% relatedness to DNAs from biovar B strains. Labeled DNA from biovar B strain Fn524T exhibited 100 to 81% relatedness to DNAs from biovar B strains and 71 to 60% relatedness to DNAs from biovar A strains. Therefore, the names Fusobacterium necrophorum subsp. necrophorum subsp. nov., nom. rev. (ex Flügge 1886), and Fusobacterium necrophorum subsp. funduliforme subsp. nov., nom. rev. (ex Hallé 1898), are proposed for Fusobacterium necrophorum biovars A and B, respectively. The type strain of F. necrophorum subsp. necrophorum is strain VPI 2891 (= JCM 3718 = ATCC 25286), and the type strain of F. necrophorum subsp. funduliforme is strain Fn524 (= JCM 3724).

Recognition of biovar C of Fusobacterium necrophorum (Flügge) Moore and Holdeman as Fusobacterium pseudonecrophorum sp. nov., nom. rev. (ex Prévot 1940)

The cellular morphology, colonial morphology, biochemical properties, DNA base compositions, and DNA-DNA homolgies of three biovars of Fusobacterium necrophorum were examined. Some differences were found among the three biovars in cellular morphology, colonial morphology, and biochemical properties. The guanine-plus-cytosine contents of DNAs from biovar C strains Fn521T (T = type strain), Fn522, and Fn520 were 30.4, 29.3, and 28.0 mol%, respectively, and the guanine-plus-cytosine contents of DNAs from strains VPI 2891 (biovar A) and VPI 6161 (biovar B) were 31.3 and 32.0 mol%, respectively. Labeled DNA from biovar C strain Fn521T exhibited 96 and 82% relatedness to DNAs from biovar C strains Fn522 and Fn520, respectively; however, it exhibited only about 10% relatedness to DNAs from strains of biovars A and B. Labeled DNAs from strains VPI 2891 and VPI 6161 exhibited more than 70% relatedness to each other, but about 6 to 20% relatedness to DNAs from biovar C strains. Therefore, Fusobacterium pseudonecrophorum sp. nov., nom. rev. (ex Prévot 1940) is proposed for Fusobacterium necrophorum biovar C. The type strain is strain Fn521 (= JCM 3722).

Pathogenicity of Fusobacterium necrophorum biovar C in mice by intraperitoneal and intraportal injections

Three strains of Fusobacterium necrophorum biovar C were injected into mice intraperitoneally and intraportally. All the mice survived. In one mouse out of 15 mice injected intraperitoneally, a few focal abscesses were formed in the liver. The microorganisms were recovered from the liver abscess and the tissue of liver with abscess. No changes were observed in the organs of other 14 mice and no bacteria were recovered from them. In the 15 mice injected intraportally, no liver abscesses and no macroscopic changes in the organs were formed. However, the inoculated bacteria were recovered from the liver of four mice. The pathogenicity of F. necrophorum biovar C was weaker than that of other two biovars.