Novel alternative splicing in the 5' exon of the neurotrophin-3 gene

The neurotrophin-3 (NT-3) gene has previously been reported to consist of three exons including two 5' short untranslated exons and a 3' long exon encoding the entire protein, and to give rise to two classes of transcripts by alternative splicing of the 5' exons to the 3' coding exon. In the present study, we demonstrated the presence of at least four new classes of transcripts of the NT-3 gene, in addition to the two known transcripts. The present finding proposes the further complexity of the regulational mechanism for NT-3 expression.

Suppressive activity of the chloroform extract of Tripterygium wilfordii Hook f on effector T cell activation during Hymenolepis nana infection in mice

The chloroform extract of Tripterygium wilfordii Hook f (TWH extract) administered into mice daily at doses of 80.0 to 200.0 micrograms/kg (but not 40.0 micrograms/kg) caused suppression of protective immunity to Hymenolepis nana when the extract was injected subcutaneously during the induction phase of protective immunity. Daily administration of 200.0 micrograms/kg TWH extract, during the course of larval development from challenge, also suppressed protective immunity. Inhibition of protective immunity was only observed in mice that received TWH extract for 6 days at a daily dose of 200.0 micrograms/kg and were challenged 24 h after the final injection. TWH extract did not inhibit formation of effector cells that mediate delayed type hypersensitivity (DTH) to H. nana egg antigen when the extract was administered subcutaneously at a dose of 200.0 micrograms/kg/day for 5 days before cell preparation. However, TWH extract did inhibit DTH effector cell activation when cells prepared from infected, PBS-injected mice were transferred into 200.0 micrograms/kg TWH extract-treated recipient mice. These results strongly indicate that TWH extract cannot inhibit the generation of effector cells but will suppress their function in vivo.

[Treatment outcome on 52 patients with 53 testicular germ cell tumors]

Between August 1983 and April 1996, 53 testicular germ cell tumors in 52 patients were treated at Toranomon Hospital. The average age of the patients was 36.1 years (range 21-89). The affected side was the right side in 24, left in 27 and bilateral in 1 case. Of the 53 tumors 34 (64.2%) were seminoma and 19 (35.8%) were non-seminomatous germ cell tumor (NSGCT). High ligation orchiectomy was performed in all cases. Of 29 stage I seminomas, post-operative adjuvant radiotherapy was performed in 6 cases prior to 1991. None of these tumors recurred. Two cases of relapses (8.7%) were found among the 23 stage I seminomas followed by surveillance. Of 8 stage I NSGCTs followed by surveillance, 4 (50.0%) tumors which contained embryonal carcinoma element and vascular invasion relapsed within 12 months after orchiectomy. A case of stage IIA seminoma was treated successfully by irradiation. Seven cases of stage II (3 seminomas and 4 NSGCTs) and 8 cases of stage III (1 seminoma and 7 NSGCTs) as well as cases of 6 stage I patients who developed relapse during surveillance were treated by VAB-6 chemotherapy. Of these 21 cases, 11 (52.4%) achieved complete response (CR) and 10 (47.6%) partial response (PR). Salvage surgery and/or additional chemotherapy was successful to bring the 10 PR cases into CR condition. One NSGCT patient, however, died of electrolyte imbalance during the maintenance chemotherapy for disease progression after achieving CR. All 34 patients with seminomas and 18 of the 19 with NSGCTs were alive without evidence of disease after a mean follow up period of 61.1 months (range 4-150 months).

Immunosuppressant deoxyspergualin induces apoptotic cell death in dividing cells

Deoxyspergualin (DSG) has been found to have an antitumour and immunosuppressive activity. However, the precise mechanism of action of DSG has not been clarified. We have used its analogue, methyldeoxyspergualin (MeDSG) for in vitro culture studies of DSG since it shows good stability in aqueous solution and retains strong immunosuppressive activity. In the present study, we found that MeDSG inhibited proliferation of rapidly dividing murine T-cell hybridomas, resulting in cell death. The cell death was accompanied by chromatin condensation and DNA cleavage at the linker regions between nucleosomes. Furthermore, MeDSG induced a reduction in mitochondrial transmembrane potential. When murine thymocytes were treated with MeDSG for 48 hr, a slight increase of DNA fragmentation was constantly observed, and selective depletion of CD4- CD8- cells was noticed. In contrast, CD4+ CD8+ cells were hardly affected. Moreover, splenic T-cells are resistant to MeDSG-induced apoptosis, as evaluated by measuring DNA cleavage. Our findings may account for the immunosuppressive and antitumour properties of DSG which were described in a number of previous studies.

Effects of N-methacryloyl amino acid applications on hybrid layer formation at the interface of intertubular dentin

To understand the role of NMAA in the bonding of composite resin to a dentin surface, we investigated the effects of N-methacryloyl amino acid (NMAA) application on the expansion of aggregated collagen fibers, formation of a hybrid layer, and the tensile bond strength between composite resin and dentin. Four NMAA derivatives--N-methacryloyl-alpha-glycine (NMGly), N-methacryloyl-gamma-amino n-butyric acid (NMBu), N-methacryloyl-alpha-hydroxyproline (NMHPro), and N-methacryloyl-alpha-glutamic acid (NMGlu)--were prepared and applied to dentin surfaces which had been etched with 40% by mass H3PO4 and air-blown. The shrunken collagenous layer expanded by approximately 50% to 70% by volume of the original collagenous layer thickness after application of the NMAA primers. Application of the bonding agent and composite resin after NMAA treatment resulted in the formation of a hybrid layer. The thickness of the hybrid layer was somewhat smaller than the collagenous layer formed by the NMAA treatment only, regardless of the type of NMAA used. The thickness of the hybrid layer was approximately ten times larger than that formed without NMAA treatment. Although all NMAA primers formed hybrid layers of similar thickness, higher tensile bond strengths, from 13 to 15 MPa, were obtained when etched and air-blown dentin was treated with NMBu, NMGly, or NMGlu. NMHPro gave only 6.6 MPa, a value similar to that obtained when no NMAA was used. We concluded, therefore, that formation of the hybrid layer is a necessary but insufficient condition for high bond strength.

Membrane targeting and binding of the 74-kDa form of mouse L-histidine decarboxylase via its carboxyl-terminal sequence

The role of the C-terminal region of the 74-kDa form of L-histidine decarboxylase (HDC) in the targeting to the endoplasmic reticulum (ER) was investigated in COS-7 cells. The deletion of a 10-kDa segment (residues 578-662) of the C-terminal end of HDC, especially a 20 amino acid sequence (residues 588-607), abrogated the targeting to the ER. The C-terminal 10-kDa portion is sufficient to target the green fluorescent protein (GFP) to the ER. The 74-kDa form of HDC synthesized in an in vitro translation system post-translationally associated with the heterogeneous canine microsomal membranes. These results suggest that the C-terminal 10-kDa portion of HDC contains a signal necessary for HDC to be targeted to the ER membrane.

Sensitization of cells to ionizing radiation by chlorin e6Na

We have investigated whether a hydrophilic photosensitizer, chlorin e6Na (Ce6Na), can sensitize cells to ionizing radiation. When V79-1 cells were pretreated with Ce6Na for 2 hr before receiving a dose of 2-14 Gy of irradiation, the cells became sensitive to X-irradiation. The sensitizing effect of Ce6Na depended on the dose of Ce6Na. The sensitizing effect also depended on the length of the treatment period before X-irradiation up to 4 hr, but not on the length of a treatment period after X-irradiation. Intracellular concentrations of Ce6Na were increased linearly after incubation with Ce6Na for periods of up to 4 h. The dose-modifying factor calculated from the survival curve was 1.25.

Characterization of a protein kinase gene responsive to auxin and gibberellin in cucumber hypocotyls

By means of the PCR, cDNA clones encoding putative protein kinases have been obtained from cucumber hypocotyls. The abundance of the transcript of one of these genes, which was named CsPK3, increased on treatment with gibberellin (GA4) and/or auxin (IAA). We screened a cucumber cDNA library to clone CsPK3 cDNA. The cDNA clone (cCsPK3) encodes an open reading frame of 1,413 bp (471 amino acids), and its predicted amino acid sequence showed homology with those of serine/threonine protein kinases. Northern blot analysis indicated that IAA was more active than GA4 in increasing the level of CsPK3 mRNA in cucumber hypocotyls and that the increase in the level of CsPK3 mRNA on treatment with IAA was not inhibited by pretreatment with a protein synthesis inhibitor. The level of CsPK3 mRNA was high in hypocotyls of dark-grown cucumber seedlings and decreased to less than 50% of the original level within 15 min of the start of irradiation with white light.

Fatal hemorrhage in irradiated esophageal cancer patients

Between 1980 and 1994, 423 patients with esophageal cancer were given curative radiation therapy. Of these patients, 31 died of massive hemorrhage and were used as the subjects of analysis in this study. The incidence of massive hemorrhage in all patients was 7% (31/423). In the 31 patients who died of massive hemorrhage, 27 had local tumors and two had no tumors at hemorrhage (two unknown cases). The mean time interval from the start of radiation to hemorrhage was 9.2 months. In 9 autopsy cases the origin of hemorrhage was a tear of the aorta in 5 cases, necrotic local tumor in 3 cases and esophageal ulcer in 1 case. The positive risk factors for this complication seemed to be excess total dose, infection, metallic stent, and tracheoesophageal fistula. Chest pain or sentinel hemorrhage proceeding to massive hemorrhage was observed in about half of the patients.

Influence of water immersion stress on peripheral nerve recovery in the rat

An experimental study was performed to investigate the relationship between stress and peripheral nerve recovery. Male Wistar rats weighing 200-250 g were used. The sciatic nerve was crushed unilaterally with an aneurysm clip. Stress was applied by water immersion for 3 h, three times a week, from 1 week preoperatively, and continued for 6 or 8 weeks. The animals' walking tracks were measured every week to evaluate nerve function, and a sciatic functional index (SFI) was calculated. Specimens for histological examination were taken from the nerve at a site distal to the crush injury. By 3 weeks postoperatively, the SFI in the non-stress groups had recovered, but it remained at significantly lower levels in the stress groups (P < 0.01). Histological studies showed that the recovery of nerve fibers was retarded and regenerating axons were smaller in the stress groups. Peripheral nerve recovery after crush injury was suppressed by water-immersion stress.

Adhesion mechanisms of resin to etched dentin primed with N-methacryloyl glycine studied by 13C-NMR

The origin of the pH-dependent bond strength of the resin to etched dentin treated with N-methacryloyl glycine (NMGly) primer was studied by 13C-nuclear magnetic resonance (NMR) including spin-lattice relaxation time, T1, observation. When the dentinal collagen was suspended in the NMGly solution at pH = 1.6, the T1 values of all the carbons attributed to the NMGly species were significantly decreased. This indicated the presence of an interaction between the NMGly and the dentinal collagen. To obtain detailed information of this interaction, the 13C-NMR spectra of the NMGly were measured in the presence of the model compound for the collagen, (Pro-Pro-Gly)5 at pH = 1.7. The 13C-NMR peaks of the carbonyl carbons of the amide and carboxylic acid in the NMGly species shifted to a higher field and the T1 values decreased. Furthermore, when the molar ratio of (Pro-Pro-Gly)5 to NMGly was decreased from 1:1 to 1:3, the T1 values of the carbonyl carbon attributed to the carboxylic acid in the C-terminal Gly residue of the oligopeptide decreased dramatically. It can be construed that this indicated the formation of a hydrogen bond between the amide, -NH and the carboxylic acid of the NMGly species and the carboxylic acid of the C-terminal Gly residue of the oligopeptide.

Distortion behavior of heat-activated acrylic denture-base resin in conventional and long, low-temperature processing methods

There have been many reports on fatal distortion of heat-activated acrylic denture-base resin which is still widely used in the field of removable prosthodontics. However, these reports have failed to report quantitatively on polymerization and thermal shrinkage factors. In the present study, we attempted to verify that the shrinkage of heat-activated acrylic denture-base resin was caused mainly by thermal contraction after processing. Furthermore, we examined the degree of distortion resulting from long, low-temperature processing, and compared the results with that of the conventional method. The strain gauge and thermo-couple were embedded in a specimen at the time of resin packing. The measurement started from the beginning of processing and continued until the specimen was bench-cooled and immediately before and after it was de-flasked, as well as during seven-day immersion in water at 37 degrees C. The resin expanded when processed by the conventional method. Meanwhile, mild shrinkage, possibly polymerization shrinkage, was observed when the resin was processed by the low-temperature method. This suggested that polymerization shrinkage was compensated for by thermal expansion during processing by the conventional method. Moreover, the shrinkage strains in the period from the completion of processing to immediately after de-flasking, in both the conventional and low-temperature methods, were identical to the theoretical value of thermal shrinkage which we obtained by multiplying the linear coefficients of thermal expansion by temperature differences. The shrinkage strain in the specimen processed by the low-temperature method, measured from the end of processing to immediately after de-flasking, averaged 64% of that in the specimen processed by the conventional method. The results revealed quantitatively that the shrinkage of heat-activated acrylic denture-base resin was mainly thermal shrinkage, and demonstrated the advantage of the low-temperature method in reducing thermal shrinkage.

Potentiation of retinoic acid-induced differentiation of HL-60 cells by prostaglandin EP2 receptor

Human promyeloid HL-60 cells are differentiated by all-trans retinoic acid (RA) to granulocytes, and prostaglandin (PG) E2 potentiates the RA-induced differentiation. Here we examined which subtype of PGE receptors was involved in this potentiating activity of PGE2. Northern blot analysis demonstrated that HL-60 cells expressed three subtypes of PGE receptor, EP2, EP3, and EP4. Among various EP agonists, and EP2-selective agonist, butaprost, preferentially potentiated the RA-induced differentiation of HL-60 cells. Butaprost not only decreased the half-maximal concentration of RA but also increased the maximal level of the differentiation. Butaprost concentration-dependently stimulated the cAMP formation, and 8-Br-cAMP strongly potentiated the RA-induced differentiation. These results demonstrate that the EP2 receptor enhances the RA-induced differentiation of HL-60 cells via stimulation of adenylate cyclase.

Deoxyspergualin preferentially inhibits the growth and maturation of anti-CD40-activated surface IgD+ B lymphocytes

Deoxyspergualin (DSG), an analogue of spermidin, is a potent immunosuppressive drug with an action quite distinct from that of cyclosporin, rapamycin, or FK506. In this study we investigated the effect of DSG and methyldeoxyspergualin (MeDSG) on the proliferation and differentiation of human B cells stimulated with anti-CD40 MoAb. Highly purified B cells obtained from tonsillar samples were used as target cells. Both agents inhibited the proliferative response of anti-CD40-stimulated B cells in the absence and presence of IL-4, IL-2 or IL-10 in a dose-dependent manner. This inhibitory effect differed markedly among cell populations based on surface IgD expression: strong inhibition of sIgD+ B cells but little inhibition of sIgD- B cells. The drugs also suppressed the production of IgG, IgM and IgA by unfractionated B cells, which suggests that DSG acts against post-switch (sIgD-) B cells. Although the drugs suppressed immunoglobulin synthesis by both sIgD+ and sIgD- B cells, the effect was more marked in the sIgD+ B cells. Analysis of the subclass of IgG secreted by sIgD+ B cells revealed a decline in IgG1 and IgG3 in the presence of DSG. These results suggest that DSG preferentially inhibits the growth and maturation of sIgD+ naive B cells.

Rice phloem thioredoxin h has the capacity to mediate its own cell-to-cell transport through plasmodesmata

Rice (Oryza sativa L.) phloem sieve tubes contain RPP13-1, a thioredoxin h protein that moves around the plant via the translocation stream. Such phloem-mobile proteins are thought to be synthesized in the companion cells prior to being transferred, through plasmodesmata, to the enucleate sieve-tube members. In this study, in-situ hybridization experiments confirmed that expression of RPP13-1 is restricted to companion cells within the mature phloem. To test the hypothesis that RPP13-1 enters the sieve tube, via plasmodesmata, recombinant RPP13-1 was expressed in Escherichia coli, extracted, purified and fluorescently labeled with fluorescein isothiocyanate (FITC) for use in microinjection experiments into tobacco (Nicotiana tabacum L.) mesophyll cells. The FITC-RPP13-1 moved from the injected cell into surrounding cells, whereas the E. coli thioredoxin, an evolutionary homolog of RPP13-1, when similarly labeled and injected, failed to move in this same experimental system. In addition, co-injection of RPP13-1 and FITC-dextrans established that RPP13-1 can induce an increase in plasmodesmal size exclusion limit to a value greater than 9.4 but less than 20 kDa. Nine mutant forms of RPP13-1 were constructed and tested for their capacity to move from cell to cell; two such mutants were found to be incapable of movement. Crystal-structure prediction studies were performed on wild-type and mutant RPP13-1 to identify the location of structural motifs required for protein trafficking through plasmodesmata. These studies are discussed with respect to plasmodesmal-mediated transport of macromolecules within the companion cell-sieve tube complex.

Fosfomycin reduces CD15s-related antigen expression of Streptococcus pyogenes

We have previously shown the immunological mimicry of human sialyl-Lewis(x) (CD15s) by a surface antigen of Streptococcus pyogenes. This mimicking surface antigen may act as a ligand to the selectin family and may induce antibody production against CD15s on host cells, suggesting a possible role in the pathogenesis of S. pyogenes. In this study, the effects of antibiotics on the CD15s-related antigen expression of S. pyogenes were examined at a concentration below the MIC (sub-MIC). The amounts of CD15s on the surfaces of S. pyogenes cells and on the surfaces of S. pyogenes biofilms were determined by a whole-cell enzyme-linked immunosorbent assay and by laser scanning fluorescence microscopy, respectively, by using an anti-CD15s monoclonal antibody. At the sub-MICs, fosfomycin (1R,2S-1,2-epoxypropyl phosphonic acid), its enantiomer (1S,2R-1,2-epoxypropyl phosphonic acid), and benzylpenicillin significantly inhibited the CD15s expression of all strains studied. The effects of fosfomycin and its enantiomer on biofilms were also observed by scanning electron microscopy. Incubation of S. pyogenes with the sub-MIC of fosfomycin or its enantiomer, which has no antibacterial activity, reduced the amount of CD15s on the biofilm surface and made it smooth. These results suggest that fosfomycin or its enantiomer might be useful for preventing S. pyogenes adherence to human CD15s receptors and the resulting immunological pathogenicity.

Gene expression of neurotrophins and their receptors in cultured rat vascular smooth muscle cells

Most previous researches on neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) have focused on the nervous system, because their receptors are widely distributed in neuronal tissues. Recently, however, the participation of neurotrophins in inflammation and atherosclerosis has been proposed. Therefore, the gene expression of neurotrophins is now an urgent issue is to be investigated in nonneuronal tissues. Here, we evaluated the gene expression of neurotrophins and their receptors in rat cultured vascular smooth muscle cells (VSMCs) by the reverse transcriptase-polymerase chain reaction method. The transcripts of NGF, NT-3, and TrkC (high-affinity receptor for NT-3), and two BDNF alternative spliced transcript variants with exons 3 and 4 were clearly detected in VSMCs cultured under conventional culture conditions. The upregulation of mRNA levels for NGF, two BDNF variants with exons 1 and 2, low-affinity neurotrophin receptor, and high-affinity receptors, TrkA (for NGF) and TrkB (for BDNF), was observed in response to the treatment with serum and phorbol-ester following the serum-starvation. In contrast, the expression of NT-3 and TrkC genes was downregulated under these conditions. Co-expression of these factors and their receptors and the characteristic regulation of their gene transcriptions suggest that these factors play crucial roles in the function of VSMCs through an autocrine mechanism.

Intracellular localization of the 74- and 53-kDa forms of L-histidine decarboxylase in a rat basophilic/mast cell line, RBL-2H3

To clarify the process of post-translational modification of L-histidine decarboxylase (HDC), we investigated the conversion of the 74-kDa form of HDC into the 53-kDa form in specialized organella of a rat basophilic/mast cell line (RBL-2H3). With treatment of streptolysin-O, RBL-2H3 cells released approximately 40% of HDC activity accompanied by over 90% of lactate dehydrogenase activity. Only the 74-kDa form of HDC was detected in the leaked fraction by SDS-polyacrylamide gel electrophoresis. The 74-kDa form in the homogenate of pulse-labeled cells was recovered in both the supernatant and particulate fractions, while the 53-kDa form was detected only in the particulate fraction containing marker proteins of microsomes, Golgi, and lysosomal granules. Confocal microscopic observation using double staining immunofluorescence with anti-GST fusion HDC antiserum showed that most of the HDC coexists with protein-disulfide isomerase, a typical marker of the luminal space of the ER. With treatment of digitonin, RBL-2H3 cells released only 74-kDa HDC. Trypsin digestion of digitonin-permeabilized cells resulted in the disappearance of the 74-kDa form but not the 53-kDa form. From these results, it is assumed that the 74-kDa form of HDC, synthesized in the cytosol, is translocated into the lumen of the ER, where it is converted to the 53-kDa form.

Down-regulation of RFL, the FLO/LFY homolog of rice, accompanied with panicle branch initiation

FLORICAULA (FLO) of Antirrhinum and LEAFY (FLY) of Arabidopsis regulate the formation of floral meristems. To examine whether same mechanisms control floral development in distantly related species such as grasses, we isolated RFL, FLO-LFY homolog of rice, and examined its expression and function. Northern analysis showed that RFL is expressed predominantly in very young panicle but not in mature florets, mature leaves, or roots. In situ hybridization revealed that RFL RNA was expressed in epidermal cells in young leaves at vegetative growth stage. After the transition to reproductive stage, RFL RNA was detected in all layers of very young panicle including the apical meristem, but absent in the incipient primary branches. As development of branches proceeds, RFL RNA accumulation localized in the developing branches except for the apical meristems of the branches and secondary branch primordia. Expression pattern of RFL raised a possibility that, unlike FLO and LFY, RFL might be involved in panicle branching. Transgenic Arabidopsis plants constitutively expressing RFL from the cauliflower mosaic virus 35S promoter were produced to test whether 35S-RFL would cause similar phenotype as observed in 35S-LFY plants. In 35S-RFL plants, transformation of inflorescence meristem to floral meristem was rarely observed. Instead, development of cotyledons, rosette leaves, petals, and stamens was severely affected, demonstrating that RFL function is distinct from that of LFY. Our results suggest that mechanisms controlling floral development in rice might be diverged from that of Arabidopsis and Antirrhinum.

Influence of self-etching primer treatment on the adhesion of resin composite to polished dentin and enamel

OBJECTIVE

This study investigated the effectiveness of the self-etching primer treatment on the adhesion of resin composite to both dentin and enamel.

METHODS

Two types of self-etching primer were prepared. One was an aqueous solution of 2-methacryloyloxyethyl phenyl hydrogen phosphate (Phenyl-P) and 2-hydroxyethyl methacrylate (HEMA), and the other was an aqueous solution of 10-methacryloxydecyl dihydrogen phosphate (MDP) and HEMA. Influence of the concentration of Phenyl-P and MDP, and that of the application time on the adhesiveness were examined by measuring the tensile bond strengths of resin composite to dentin and enamel. The data were analyzed using the analysis of variance and Scheffe's test for multiple comparison among the means.

RESULTS

After the 20P and 30P treatment for 30 s, bond strengths to dentin were significantly higher than those after 5P and 10P treatment for 30 s. The 30M treatment of dentin for 15 s significantly increased the bond strength compared with 5P, 10P and 20P for 15 s. In enamel, bond strength with 30P for 60 s was significantly higher than with 5P for 60 s and 30P for 15 s. The 30M for 60 s resulted in significantly higher bond strength than for 15 s. The smear layers on the dentin and enamel were partially dissolved by the self-etching primer treatment. A hybrid layer with a thickness of 1-1.5 microns was formed in dentin-bonded specimens.

SIGNIFICANCE

The self-etching primer containing Phenyl-P or MDP showed good adhesion to dentin and enamel, and this primer is a promising material for resin composite restoration.

Efficacy of self-etching primers containing carboxylic acid monomers on the adhesion between composite resin and dentin

A study was conducted to examine the efficacy of carboxylic acid monomers as self-etching primers by measuring the tensile bond strengths between composite resin and dentin. Several kinds of carboxylic acid monomers, such as o-(N-methacryloyl amino)benzoic acid (o-MABA), m-(N-methacryloyl amino)benzoic acid (m-MABA), p-(N-methacryloyl amino)benzoic acid (p-MABA), 4-methacryloxy phthalic acid (4-MPA), 2-(N-methacryloyl amino) terephthalic acid (2-MATPA), and 5-(N-methacryloyl) amino)isophthalic acid (5-MAIPA), were prepared. 4-methacryloxyethyl trimellitic anhydride (4-META) was also used as a component of the self-etching primer. The DMSO solutions of these monomers were used as self-etching primers. The tensile bond strengths between composite resin and dentin were measured after 24 h immersion in water at 37 degrees C. When DMSO was used as a self-etching primer, the bond strengths were below 5 MPa. Among the monocarboxylic acid monomers, m-MABA gave the highest mean bond strength at 60 s application, and 5MAIPA gave the highest mean bond strength at 30 s application among the dicarboxylic acid monomers, although the differences among the values were not always significant. The smear layer was partially dissolved by treatment with the self-etching primer.

The relative biological effectiveness of the modulated proton beam at TRIUMF

PURPOSE

The purpose of this study was to determine the relative biological effectiveness (RBE) of proton beam and to study its dependency on fraction number.

METHODS

The relative biological effectiveness (RBE) of fractionated protons compared with 60Co gamma-rays was investigated for the acute mouse skin reaction. The 80 MeV protons generated at the TRIUMF cyclotron were spread out from 7 to 25 mm to irradiate entire legs. One, two, four, and eight fractions were tested.

RESULTS

RBE values ranged from 1.15 to 1.24 for the acute skin reaction. Fraction dose dependence of RBEs was not observed.

Spinal fusion using a vascularized fibular bone graft for a patient with cervical kyphosis due to neurofibromatosis

We performed an anterior spinal fusion using a vascularized fibular bone graft combined with posterior fusion for a patient with severe cervical kyphosis due to neurofibromatosis. The kyphosis was corrected from 85 degrees preoperatively to 38 degrees postoperatively. A vascularized fibular bone graft is a useful surgical procedure in selected patients to obtain successful bony union.

Unique action of an immunosuppressive agent, deoxyspergualin, on hematopoiesis in mice

Deoxyspergualin (DSG) is an immunosuppresive agent of proven effectiveness in the prevention and treatment of transplant rejection; its most frequent side effect is reversible bone marrow suppression. To clarify the mechanisms of bone marrow suppression induced by DSG, we monitored the numbers of peripheral blood and marrow stem cells in C3H/HeN mice receiving 14 days of DSG injections at a highly immunosuppressive dose of 10 mg/kg/day. In the peripheral blood cells, DSG induced severe anemia and mild leukopenia because of a decrease in granulocyte counts, although these phenomena were reversible. During DSG administration, nucleated cell counts in the femur also markedly decreased, whereas the absolute numbers of various stem cells and progenitor cells, except for erythroid colony-forming units (CFU-E), remained normal or increased; CD34- or c-kit-positive and lineage-negative cell levels markedly increased on the day DSG administration ceased. These findings indicate that DSG-induced anemia and leukopenia are not initiated by a generalized killing of these stem cells, but rather by a transient suppression of their ability to mature. Significantly, the severe anemia induced by DSG resembles pure red cell aplasia in humans, because there were marked decreases in peripheral reticulocytes, marrow CFU-E, and erythroblasts, with no decrease in renal erythropoietin mRNA expression. Furthermore, DSG-induced anemia was completely ameliorated by treatment with human recombinant erythropoietin.