Bordetella bronchiseptica dermonecrotizing toxin stimulates protein synthesis in an osteoblastic clone, MC3T3-E1 cells

Abstract The effects of Bordetella bronchiseptica dermonecrotizing toxin on protein synthesis in an osteoblastic clone, MC3T3-E1 cells, were investigated. The rate of protein synthesis in the serum-starved cells was increased by the toxin after a latent period of about 4 h, and reached 2.5 times that of the control 24 h after addition of toxin. The toxin raised the level of protein synthesis even in actively proliferating cells. The stimulatory effect of the toxin on protein synthesis occurred earlier than other toxic events so far reported, such as the stimulation of DNA synthesis and the inhibition of osteoblastic differentiation, and was apparently dependent on the toxin concentrations over the range 0.05 ng ml⁻¹ to 6.0 ng ml⁻¹. Therefore, the stimulatory effect of the toxin on protein synthesis could be useful in determining the mode of action of the toxin.     

The inhibitory effect of T-2 toxin on tolerance induction of delayed-type hypersensitivity in mice.

Mice injected intravenously with 1 X 10(9) sheep red blood cells (SRBC) showed no delayed-type hypersensitivity (DTH) response to SRBC and were unresponsive to DTH induction by sc injection of an optimal dose of SRBC. However, when treated with T-2 toxin, a mycotoxin, 2 days after the iv injection, mice became to show significant DTH response and to be responsive to the DTH induction by the sc injection. When the spleen cells of the mice receiving the iv injection were transferred to unsensitized syngeneic recipients, the DTH response of the recipients to SRBC was suppressed. However, the suppressor activity of the spleen cells was decreased by T-2 toxin treatment. By the iv injection, cell population of the spleen was increased and that of the thymus decreased. In contrast, by T-2 toxin treatment 2 days after the iv injection, cell population of the spleen was not increased and that of the thymus was markedly decreased. The ratio of theta-bearing cells was increased in the spleen by the iv injection. However, such increase was not observed after the T-2 toxin treatment. The ratio of Ig-bearing cells in the spleen was not changed by the iv injection and the T-2 toxin treatment after the iv injection. T-2 toxin seems to interfere with generation of suppressor cells for the DTH response.     

Characterization of midface maxillary membranous bone formation during distraction osteogenesis

The purpose of the study was to follow the early events in bone formation and neovascularization during maxillary distraction and after the consolidation period and to define the characterization of the new bone in the distracted area. Maxillary osteotomy was performed in seven sheep. In five animals, an external distraction device was used for maxillary lengthening of 20 mm at a rate of 1 mm/day for 20 days. Another two animals served as controls without distraction. Sequential biopsies were performed. The methods used for analysis were histologic, immunohistochemical, and ultrastructural by transmission electron microscopy. During the 5 days of latency, a fibrin clot was formed that after 5 days of distraction was replaced by granulation tissue, proliferating mesenchyme-like cells, and capillaries. After 10 days of distraction, the regenerated tissue could be divided into three main zones and two transitional areas: a central zone occupied by many polygonal mesenchyme-like cells and spindle-shaped cells that proliferated intensively; two paracentral zones on both sides of the central zone in which many cells showed morphologic signs of apoptosis leading to a decreased number of fibroblast-like cells embedded in wavy collagen fibers; a transitional area from the central to the paracentral zone in which concentric cellular colonies were believed to represent a novel form of vasculogenesis; distal-proximal zones, located on both sides of the paracentral zones and in continuation with the old bone, showed delicate new woven bone trabeculae that grew continuously in the direction of lengthening and gradually became mineralized; and a transitional area from the paracentral to the distal-proximal zones in which there was recruitment of preosteoblasts from the distracted tissue to the trabecular tips. These further differentiated into osteoblasts that contributed to the trabecular growth. The histologic feature pattern was similar after 15 and 20 days of continuous distraction. At the end of lengthening, after 20 days, delicate longitudinally oriented trabeculae continued to grow by recruiting preosteogenic cells from the central distracted tissue, became mineralized, and were rimmed by osteoblasts. After 6 weeks of retention, the trabeculae thickened and consisted of a mixture of lamellar and woven bone. In conclusion, the distraction force creates a pool of undifferentiated mesenchyme-like cells with osteogenic potential and triggers capillary formation, a clear zonation can be observed during active lengthening, and new bone trabeculae begin to form between 5 and 10 days after distraction, soon become aligned with osteoblasts, and continue to grow as long as distraction force is applied. This characterization may help in any exogenous involvement with growth factors to improve bone quality.     

不同方式构建A20鼠B细胞淋巴瘤动物模型

目的探索多种方式构建A20鼠B细胞淋巴瘤动物模型及不同方式造模成瘤的特征。方法鼠源性B细胞淋巴瘤细胞株A20经皮下、尾静脉、脾脏和腹腔接种于同源BALB/c小鼠或先接种裸鼠成瘤后组织块移植BALB/c小鼠,观察动物成瘤时间、成瘤率、成瘤部位;取肿瘤组织和动物脏器行石蜡包埋、病理切片、HE染色观察其组织学特点。结果BALB/c鼠皮下注2×10^6组、2×10^7组和裸鼠瘤组织移植BALB/c小鼠组成瘤率皆为100%,成瘤时间分别为（15.29±3.2）d（、7.0±0.82）d和（6.29±0.49）d。BALB/c小鼠尾静脉注射2×106组、2×107组、脾脏注射组、腹腔注射组成瘤率分别为71.4%、100%、71.4%、14.3%,成瘤时间分别为（76.8±12.0）d、（26.1±7.99）d、（32.6±5.99）d和27 d。尾静脉成瘤部位播及肝脏、脾脏、胰腺、肾脏、食道、胃、肠、肠系膜、脑、淋巴结、骨、子宫、肌肉等多脏器和组织。BALB/c鼠A20成瘤组织学类似人弥漫大B细胞淋巴瘤。结论成功构建A20皮下移植瘤模型、血行播散性模型,为利用有免疫功能动物进行B淋巴瘤相关研究提供了实验平台。     

Expression of myosin isoforms during notexin-induced regeneration of rat soleus muscles

Myosin isozymes and their fiber distribution were studied during regeneration of the soleus muscle of young adult (4-6 week old) rats. Muscle degeneration and regeneration were induced by a single subcutaneous injection of a snake toxin, notexin. If reinnervation of the regenerating muscle was allowed to occur (functional innervation nearly complete by 7 days), then fiber diameters continued to increase and by 28 days after toxin treatment they attained the same values as fibers in the contralateral soleus. If the muscles were denervated at the time of toxin injection, the early phases of regeneration still took place but the fibers failed to continue to increase in size. Electrophoresis of native myosin showed multiple bands between 3 and 21 days of regeneration which could be interpreted as indicating the presence of embryonic, neonatal, fast and slow myosins in the innervated muscles. Adult slow myosin became the exclusive from in innervated regenerates. In contrast, adult fast myosin became the predominant form in denervated regenerating muscles. Immunocytochemical localization of myosin isozymes demonstrated that in innervated muscles the slow form began to appear in a heterogeneous fashion at about 7 days, and became the major form in all fibers by 21-28 days. Thus, the regenerated muscle was almost entirely composed of slow fibers, in clear contrast to the contralateral muscle which was still substantially mixed. In denervated regenerating muscles, slow myosin was not detected biochemically or immunocytochemically whereas fast myosin was detected in all denervated fibers by 21-28 days. The regenerating soleus muscle therefore is clearly different from the developing soleus muscle in that the former is composed of a uniform fiber population with respect to myosin transitions. Moreover the satellite cells which account for the regeneration process in the soleus muscle do not appear to be predetermined with respect to myosin heavy chain expression, since the fibers they form can express either slow or fast isoforms. The induction of the slow myosin phenotype is entirely dependent on a positive, extrinsic influence of the nerve.     

Characteristics of the reactions to N-alloantigens of lymphoid cells from hydrocortisone-stimulated and adrenalectomized mice]

The capacity of the spleen, bone marrow and thymus cells from CBA mice (intact, adrenalectomized, and those treated with single or repeated hydrocortisone injections) to induce the lymph node type of "graft-versus-host" reaction (GVHR) in (CBA X C57BL) F1 hybrid recipients was evaluated. Two days after 2.5 mg hydrocortisone injection the capacity of the spleen and bone marrow cells to induce GVHR increased while that of the thymus cells remained unchanged. Seven and particularly 15 days after hydrocortisone injection the spleen cells became less active. Two days following repeated daily hormone injections in a dose of 0.25 mg within 18 days the thymocyte activity in GVHR increased, while that of the spleen and bone marrow cells did not change.     

Exchange of a single amino acid switches the substrate properties of RhoA and RhoD toward glucosylating and transglutaminating toxins

Rho GTPases are the preferred targets of various bacterial cytotoxins, including Clostridium difficile toxins A and B, Clostridium sordellii lethal toxin, the cytotoxic necrotizing factors (CNF1) from Escherichia coli, and the dermonecrotizing toxin (DNT) from Bordetella species. The toxins inactivate or activate specific sets of Rho GTPases by mono-O-glucosylation and deamidation/transglutamination, respectively. Here we studied the structural basis of the recognition of RhoA, which is modified by toxin B, CNF1, and DNT, in comparison with RhoD, which is solely a substrate for lethal toxin. We found that a single amino acid residue in RhoA and RhoD defines the substrate specificity for toxin B and lethal toxin. Change of serine 73 to phenylalanine in RhoA turned RhoA into a substrate for lethal toxin. Accordingly, change of the equivalently positioned phenylalanine 85 in RhoD with serine allowed glucosylation by toxin B. Comparable results were achieved with the Rho-activating and transglutaminating enzymes CNF1 and DNT. Here, amino acid glutamate 64 of RhoA and the equivalent aspartate 76 of RhoD define substrate specificity for CNF1 and DNT, respectively. These data indicate that single amino acid residues located in the switch II region of Rho proteins determine enzyme specificity for diverse bacterial toxins.     

Effects of spaceflight on structural and material strength of growing bone

Rats in space for 18.5 days did not exhibit the normal gain in femoral bone strength of terrestrial controls. The strength deficit may have been caused by multiple factors including a diminished bone formation and an inhibition of the gain in tissue material strength. Centrifugation at 1g in space substantially enhanced bone strength, possibly by promoting more normal tissue maturation. Full recovery of bone strength was achieved 25 days after reentry.     

Action Mechanism of Fibroblast Growth Factor-2 (FGF-2) in the Promotion of Periodontal Regeneration in Beagle Dogs

Fibroblast growth factor-2 (FGF-2) enhances the formation of new alveolar bone, cementum, and periodontal ligament (PDL) in periodontal defect models. However, the mechanism through which FGF-2 acts in periodontal regeneration in vivo has not been fully clarified yet. To reveal the action mechanism, the formation of regenerated tissue and gene expression at the early phase were analyzed in a beagle dog 3-wall periodontal defect model. FGF-2 (0.3%) or the vehicle (hydroxypropyl cellulose) only were topically applied to the defect in FGF-2 and control groups, respectively. Then, the amount of regenerated tissues and the number of proliferating cells at 3, 7, 14, and 28 days and the number of blood vessels at 7 days were quantitated histologically. Additionally, the expression of osteogenic genes in the regenerated tissue was evaluated by real-time PCR at 7 and 14 days. Compared with the control, cell proliferation around the existing bone and PDL, connective tissue formation on the root surface, and new bone formation in the defect at 7 days were significantly promoted by FGF-2. Additionally, the number of blood vessels at 7 days was increased by FGF-2 treatment. At 28 days, new cementum and PDL were extended by FGF-2. Moreover, FGF-2 increased the expression of bone morphogenetic protein 2 (BMP-2) and osteoblast differentiation markers (osterix, alkaline phosphatase, and osteocalcin) in the regenerated tissue. We revealed the facilitatory mechanisms of FGF-2 in periodontal regeneration in vivo. First, the proliferation of fibroblastic cells derived from bone marrow and PDL was accelerated and enhanced by FGF-2. Second, angiogenesis was enhanced by FGF-2 treatment. Finally, osteoblastic differentiation and bone formation, at least in part due to BMP-2 production, were rapidly induced by FGF-2. Therefore, these multifaceted effects of FGF-2 promote new tissue formation at the early regeneration phase, leading to enhanced formation of new bone, cementum, and PDL.     

Persistence of specific antigenic protein in the serum of chickens given intravenously botulinum toxin type B, C, D, E or F

A sublethal dose of Clostridium botulinum progenitor toxin of each of types B, C, D, E, and F was injected once intravenously into chickens. Blood samples were withdrawn periodically from the chickens to determine the toxin remaining in the serum by the mouse injection test and by enzyme-linked immunosorbent assay (ELISA) for both toxic and nontoxic components composing the progenitor toxin. Both components were detected by ELISA for at least a few days after the serum had became innocuous to mice, indicating a higher stability of the antigenicities of both components than the lethal toxicity in the chicken serum. For the diagnosis of botulism, it seems justified to recommend detection of the antigen (toxic component or nontoxic component or both) by ELISA even if no toxin is detected by the mouse test. Such immunological tests would no doubt contribute to an increase in the rate of diagnosis of human and animal botulism cases, particularly when blood sampling is delayed.     

Induction of periosteal callus formation by bone morphogenetic protein-2 employing adenovirus-mediated gene delivery.

Although the chondrogenic response of periosteum is well established in healing fractures, the mechanisms mediating the proliferation and differentiation of periosteal chondroprogenitor cells are poorly understood. In the present study we demonstrate that bone morphogenetic protein-2 (BMP-2), introduced by adenovirus-mediated gene transfer, alone is capable of inducing callus formation at the site of periosteal injection. Both immunohistochemistry and Northern analysis demonstrated activation of type II collagen production between days 4 and 7 after the injection, followed by activation of type X collagen expression. The activation of chondrogenesis was associated with increased expression of L-Sox5 and Sox9, suggesting that the BMP-2 effect is mediated via Sox proteins. This capacity of adenovirus-mediated overproduction of BMP-2 to induce chondrogenesis (and subsequent endochondral ossification) should be useful for tissue engineering of cartilage and bone.     

Rho GTPases as targets of bacterial protein toxins

Several bacterial toxins target Rho GTPases, which constitute molecular switches in several signaling processes and master regulators of the actin cytoskeleton. The biological activities of Rho GTPases are blocked by C3-like transferases, which ADP-ribosylate Rho at Asn41, but not Rac or Cdc42. Large clostridial cytotoxins (e. g., Clostridium difficile toxin A and B) glucosylate Rho GTPases at Thr37 (Rho) or Thr35 (Rac/Cdc42), thereby inhibiting Rho functions by preventing effector coupling. The 'injected' toxins ExoS, YopE and SptP from Pseudomonas aeruginosa, Yersinia and Salmonella ssp., respectively, which are transferred into the eukaryotic target cells by the type-III secretion system, inhibit Rho functions by acting as Rho GAP proteins. Rho GTPases are activated by the cytotoxic necrotizing factors CNF1 and CNF2 from Escherichia coli and by the dermonecrotizing toxin DNT from B. bronchiseptica. These toxins deamidate/transglutaminate Gln63 of Rho to block the intrinsic and GAP-stimulated GTP hydrolysis, thereby constitutively activating the GTPases. Rho GTPases are also activated by SopE, a type-III system injected protein from Salmonella ssp., that acts as a GEF protein.     

Pertussis toxin induces lymphocytosis in rhesus macaques

Abstract: Lymph nodes and other solid tissues of the immune system are the principal sites for antigen presentation and lymphocyte activation. Lymphocytes in peripheral blood recognize the high endothelial venules within lymphoid tissues and cross from blood to tissue by the process of extravasation. Pertussis toxin is known to block extravasation and cause lymphocytosis in murine models but has not been studied extensively in nonhuman primates. We used intravenous injection of soluble pertussis toxin to induce a transient lymphocytosis in rhesus monkeys. The increase in total white blood cells was proportionally greater for lymphocytes than for polymorphonuclear cells and the CD4+ lymphocyte subpopulation increased more than the CD8+ cell population. The presence of immature polymorphonuclear cells suggested some activation of bone marrow. Clinical chemistry studies revealed an effect of pertussis toxin on liver function. Pertussis toxin is a powerful immunomodulatory agent that can disrupt and reorganize solid lymphoid tissues.     

Chlorazol Fast Pink as an in Vivo Stain for Unmineralized Bone and Tooth Matrix

The present investigation was carried out with the intention of using in vivo injections of chlorazol fast pink to mark the beginnings of bone formation in experimental skeletal fluorosis. Experiments show, however, that any uncalcified osteoid stains red, irrespective of whether it has been recently laid down or not. The staining is acid fast and hard tissues can be decalcified without loss of the dye. In vivo staining of the matrix by chlorazol fast pink does not appear to affect the growth of the tissue or its subsequent calcification and, therefore, provides a means of labelling bone surfaces at any stage during a continued experiment. Chlorazol fast pink is readily released from bone matrix by the β toxin of Clostridium histolyticum but not by other proteinases, which suggests that the dye is attached to collagen. The matrix of dentine differs from that of bone in that it is attacked both by the β toxin and the γ toxin of Clostridium histolyticum. No explanation of this difference between bone and dentine can be given.     

The role of the bone marrow in forming an immunological memory to Staphylococcus

The dynamic study of antibody formation in the bone marrow tissue of mice immunized with corpuscular staphylococcal antigen was made. A single intravenous injection of this antigen to the animals produced no essential changes in the number of antibody-forming cells in the bone marrow, their repeated immunization led to the involvement of the bone marrow in the anamnetic reaction, which was manifested by the accumulation of a great number of plasmocytes synthesizing antibodies to staphylococci in bone marrow tissue. The relative contribution of the bone marrow to systemic antibody formation essentially increased at later stages of secondary immune response. The possible biological significance of the regularities and the practical importance of the data revealed in this investigation are discussed.     

Competitive relations between tetanus anatoxin and toxin]

Experiments were conducted on albino mice; it was shown that preliminary injection of tetanus toxoid enhanced the animal resistance to tetanus toxin, this being expressed in increase in LD50. The effect increased the higher doses of the toxoid and their fractional injection. By using protagon and crude mitochondrial fraction isolated from the brain as a receptor of tetanus toxin in the nervous tissue there were established competitive relations for the receptor between the tetanus toxoid and the toxin. The results of investigations confirmed the authors' earlier statement that the molecule of the tetanus toxin contained different functional groups responsible for the toxin binding with the receptor in the nervous tissue, for the pathogenic action of the toxin and for the binding of the toxin with antitoxin.     

Mycotoxin from a Blue-Eye Mold of Corn

High-moisture yellow dent corn became heavily molded by Penicillium martensii after storage for 6 months at 1 C. Mice ingesting corn molded by P. martensii died within a few days. The toxin was isolated and identified as penicillic acid. Large quantities of the toxin accumulated over a 3-month period on artificially inoculated corn incubated at temperatures between 1 and 15 C. At higher temperatures, the toxin disappeared within 45 days.     

Ectopic bone formation in titanium mesh loaded with bone morphogenetic protein and coated with calcium phosphate

The osteoinductive properties of porous titanium fiber mesh, with or without a calcium phosphate coating and loaded with recombinant human bone morphogenic protein-2 (rhBMP-2) or rhBMP-2 and native bovine BMP (S-300) were investigated in a rat ectopic assay model. A total of 112 calcium phosphate-coated and 112 noncoated porous titanium implants, either loaded with rhBMP-2 and S-300 or loaded with rhBMP-2 alone, were subcutaneously placed in 56 Wistar-King rats. The rats were killed 5, 10, 20, and 40 days postoperatively, and the implants were retrieved.Histologic analysis demonstrated that all growth factor and carrier combinations induced ectopic cartilage and bone formation at 5 and 10 days, respectively. At 20 days, bone formation increased and was characterized by trabecular bone and bone marrow-like tissue. At 40 days, more lamellar bone and hemopoietic bone marrow-like tissue were present. At both times, more bone had been formed in calcium phosphate-coated implants than in noncoated samples. Further, in rhBMP-2 and S-300-loaded specimens, bone formation was higher than in rhBMP-2 only-loaded specimens. In rhBMP-2 only-loaded specimens, bone formation was mainly localized inside the mesh material, whereas in specimens loaded with both rhBMP-2 and S-300, the bone was localized inside and surrounding the titanium mesh. The histological findings were confirmed by calcium content and alkaline phosphatase activity measurements. In addition, all specimens showed osteocalcin expression as early as 5 days postoperatively.Our results show that the combination of titanium mesh with BMPs can induce ectopic bone formation and that this bone formation seems to be similar to "enchondral" ossification. In addition, a thin calcium phosphate coating can have a beneficial effect on the bone-inducing properties of a scaffold material. Finally, rhBMP-2 and native BMP act synergistically in ectopic bone induction.     

Rubratoxin production by penicillium rubrum when grown in a synthetic medium containing different sources of carbon and nitrogen

A sterile mineral salts broth was fortified with different additives, inoculated with conidia ofPenicillium rubrum P-13, and incubated quiescently for 14 days or with shaking for 3 to 5 days. Maximal fungal growth and rubratoxin production occurred when the broth contained 20% sucrose. Broth with 10% glucose, 10% fructose, 5% maltose, or 1% asparagine supported formation of substantial amounts of rubratoxin (52.9–78.5 mg/100 ml). When the broth was fortified with glucose plus lysine, arginine aspartic acid, cystine, ammonium citrate, or ammonium phosphate, moderate amounts (27.5–39.5 mg/100 ml) of rubratoxin and mycelium (0.1–1.5 g/100 ml) were produced. Presence in the broth of 5% galactose or starch resulted in accumulation of small amounts (22.2 and 24.6 mg/100 ml, respectively) of rubratoxin and mold tissue (0.70 and 0.5 g/ 100 ml, respectively). Whereas some toxin was recovered from mineral salts broth fortified with lactose or ribose, toxin was not recovered when the mold grew in broth containing mannitol or fumarate. With the exception of gluconate which supported some growth and toxin formation and ethanol which permitted formation of small amounts of toxin, other carbon sources resulted in little or no fungal growth and no toxin formation. Yields of rubratoxin decreased with an increase in amount of agitation or length of incubation ofP. rubrum cultures. Mold growth increased and toxin formation decreased with an increase in volume of culture.     

An in vitro assay of bone development using fetal long bones of mice: morphological studies

The purpose of this study was to examine the morphological changes in an in vitro system in which the two elements of bone modelling, formation and resorption, could be studied simultaneously. Pregnant mice were killed on days 15, 16 and 17 of gestation, the fetuses were removed and the radii and ulnae dissected free of soft tissue. The bones were cultured for 6 days in media (BGJ) supplemented with 20% fetal calf serum and 150 micrograms/ml vitamin C. Growth and mineralization were estimated by measuring the total length of the bone, and diaphysis, and by light and transmission electron microscopy (TEM). The results of this study indicate that there is a continuous measurable increase in the total length of fetal mouse long bones over the 6 days of culture. These bones show a continuous growth of periosteal bone, with mesenchymal tissue penetrating into the diaphyseal shaft, and development of bone marrow like tissue. TEM examination showed differentiation of mesenchymal cells to osteoblasts, formation of new bone matrix and bone mineralization similar to that found in developmentally matched controls. In the cartilagenous epiphyses, however, many hydroxyapatite crystals were not associated with matrix vesicles. In addition, some of the chondrocytes of the hypertrophic zone appeared to be dedifferentiating into mesenchymal cells with osteoblast-like features. In spite of the lack of osteoclasts in the 15- and 16-day explants, osteoclasts appeared in the diaphysis after 2 and 4 days in culture. Our results suggest that this system can serve as a good model for the study of bone formation and resorption as they occur, simultaneously, during bone modelling.(ABSTRACT TRUNCATED AT 250 WORDS)