Structural dependence of apatite formation on titania gels in a simulated body fluid

The apatite-forming ability of titania gels with different structures has been investigated in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma. Titania gels with an amorphous structure or with an anatase or rutile structure were prepared by the sol-gel process with a subsequent heat treatment at various temperatures. The titania gels with an amorphous structure did not induce apatite formation on their surfaces in the simulated body fluid, whereas gels with an anatase or rutile structure induced apatite formation on their surfaces. The deposition of apatite was more pronounced on the anatase gels than on the rutile gels. This indicates that a specific structure of titania is effective in inducing apatite formation in a body environment. Such a specific structure was assumed in this study to be the crystalline planar arrangement in the anatase structure, which facilitates epitaxy of the apatite crystal.     

Identification and comparison of residues critical for cell-adhesion activities of two neutrophil CD66 antigens, CEACAM6 and CEACAM8

CEACAM6 (CD66c) and CEACAM8 (CD66b) are cell-adhesion proteins on neutrophils that belong to the human carcinoembryonic antigen (CEA) family. CEACAM6 reveals homophilic adhesion and heterophilic adhesion to other CEACAM family antigens including CEACAM8, CEACAM1, and CEA, whereas CEACAM8 exhibits only heterophilic adhesion to CEACAM6. Here, we investigated and compared structural requirements for the homophilic adhesion of CEACAM6 and heterophilic adhesion between CEACAM6 and CEACAM8 at the amino acid level by using CHO transfectants expressing their mutant and chimeric proteins. The NH(2)-terminal domain (N-domain) of CEACAM6 expressed on a CHO cell was suggested to bind the N-domain of CEACAM6 or CEACAM8 on the opposing cell. By homologue-scanning mutagenesis, we found that the locations of the sequences critical for the adhesion of CEACAM6 to itself and to CEACAM8 are overlapped and that they are highly similar but not identical to the locations of the residues previously shown to be essential for the binding of CEACAM antigens to Opa proteins of pathogenic NEISSERIAE: Our findings imply that subtle differences in the N-domain sequences determine the specificity of the CEACAM antigens on neutrophils for interaction with the same or different CEACAM antigens and the bacterial proteins.     

Epidemiology of Campylobacter jejuni isolated from patients with Guillain-Barré and Fisher syndromes in Japan

Campylobacter jejuni isolation is the standard for the diagnosis of this type of bacterial infection, but there have been no epidemiological studies of a large number of C. jejuni isolates from patients with Guillain-Barre syndrome (GBS) and Fisher syndrome (FS). For 13 years, stool specimens from GBS/FS patients have been sent from 378 hospitals throughout Japan to the Tokyo Metropolitan Institute of Public Health. A total of 113 strains (11%) were isolated from the stool specimens from 1,049 patients. The isolation rate did not differ by region. The rates were 22% for 449 patients with a history of diarrhea and 2% for the others. An additional 18 isolates were provided by various hospitals. There was no noticeable seasonal distribution in the onset of C. jejuni isolated from patients with GBS/FS. The male/female ratios were 1.7:1 for GBS and 2.2:1 for FS. The patient age range showed a peak in 10- to 30-year-old subjects who had GBS and in 10- to 20-year-old subjects who had FS. The predominance of young adults and male patients who had C. jejuni-associated GBS/FS may be related to the preponderance of young adults and male patients who had C. jejuni enteritis. The median interval from diarrhea onset to neurologic symptom onset was 10 days for GBS/FS. Penner's C. jejuni serotype HS:19 was more frequently present in GBS (67%) than in enteritis (6%) patients. HS:2 was more frequent in FS (41%) than in enteritis (14%) patients. These findings suggest that certain C. jejuni strains specifically trigger GBS and that others specifically trigger FS.     

Virulence of Rhodococcus equi isolates from patients with and without AIDS.

Rhodococcus equi is an emerging opportunistic pathogen of human immunodeficiency virus-infected patients. Thirty-nine isolates of R. equi from immunocompromised patients with and without AIDS were analyzed for the presence of virulence plasmid DNA, expression of 15- to 17-kDa antigens, and their pathogenicities in mice. Of the human isolates, eight contained an 85-kb virulence plasmid, expressed 15- to 17-kDa antigens, and were virulent in mice. Nineteen isolates carried cryptic plasmids of various sizes, and the remaining 12 isolates did not contain any plasmids. These 31 isolates did not express virulence-associated antigens and were not virulent in mice. The results suggested that opportunistic infections in immunocompromised patients could be caused by both virulent and avirulent R. equi strains and that the pathogenesis of R. equi infection in immunocompromised patients appears to be different from that which occurs in foals.     

Invasive fungal infection following reduced-intensity cord blood transplantation for adult patients with hematologic diseases.

Invasive fungal infection (IFI) is a significant complication after allogeneic hematopoietic stem cell transplantation (HSCT); however, we have little information on its clinical features after reduced intensity cord blood transplantation (RICBT) for adults. We reviewed medical records of 128 patients who underwent RICBT at Toranomon Hospital between March 2002 and November 2005. Most of the patients received purine-analogbased preparative regimens. Graft-versus-host disease (GVHD) prophylaxis was a continuous infusion of either tacrolimus 0.03 mg/kg or cyclosporine 3 mg/kg. IFI was diagnosed according to the established EORTC/NIH-MSG criteria. IFI was diagnosed in 14 patients. Thirteen of the 14 had probable invasive pulmonary aspergillosis and the other had fungemia resulting from Trichosporon spp. Median onset of IFI was day 20 (range: 1-82), and no patients developed IFI after day 100. Three-year cumulative incidence of IA was 10.2%. Four of the 13 patients with invasive aspergillosis (IA) developed grade II-IV acute GVHD, and their IA was diagnosed before the onset of acute GVHD. The mortality rate of IFI was 86%. Multivariate analysis revealed that the use of prednisolone >0.2 mg/kg (relative risk 7.97, 95% confidence interval 2.24-28.4, P = .0014) was a significant risk factor for IA. This study suggests that IFI is an important cause of deaths after RICBT, and effective strategies are warranted to prevent IFI.     

Effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in undifferentiated thyroid carcinoma

Although attempts have been made to treat undifferentiated thyroid carcinoma using multidisciplinary therapeutic procedures including surgery, radiotherapy, and chemotherapy, the prognosis of undifferentiated thyroid carcinoma remains quite poor. New approaches to increase the sensitivity of patients to anticancer drugs and radiation will be needed to improve the survival rate for undifferentiated thyroid carcinoma. We examined the effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in the 8305C undifferentiated thyroid carcinoma cell line. The drug sensitivity was evaluated by MTT assay for 48 h, while apoptosis was assessed according to the formation of internucleosomal DNA ladders. The Bcl-2 antisense was introduced into 8305C cells by using a 18-mer phosphorothioate oligonucleotide by lipopolyamine-mediated transfection twice for 12 h. The expression of apoptosis genes was assessed by Western blotting. The 8305C cells were sensitive to adriamycin (ADM), mitomycin (MMC), docetaxel (TXT), and paclitaxel (TXL), showing mean IC50 values of 0.72, 1.1, 1.3, and 4.1 microM, respectively. In contrast, the 8305C cells were resistant to cisplatin (CDDP) and 5-fluorouracil (5-FU), with mean IC50 values of 42.0 and 48.0 microM, respectively. Treatment with Bcl-2 antisense suppressed the protein level of Bcl-2 in 8305C cells in a dose-dependent manner up to 1.0 microM. Drug-sensitivity was increased by pretreatment with Bcl-2 antisense as assessed by the IC50 (x-fold): 0.48 (1.5-fold) in ADM; 0.42 (2.6-fold) in MMC, 0.56 (2.3-fold) in TXT, 1.5 (2.7-fold) in TXL, 8.6 (4.9-fold) in CDDP, and 25.0 (1.9-fold) in 5-FU, respectively. The increased drug-sensitivity was associated with the induction of apoptosis-related proteins, Fas, caspase 8, cytochrome c, caspase 3, and to subsequent apoptosis, as determined by the formation of internucleosomal DNA ladders and PARP in the treated cells. Susceptibility in apoptotic cell death following treatment with anticancer drugs was associated with induction of apoptosis-related genes in undifferentiated thyroid carcinoma cells, and induction of apoptosis was enhanced by pretreatment with Bcl-2 antisense oligonucleotide. These results imply a potential new strategy targeting an antiapoptotic protein, Bcl-2, by its antisense oligonucleotide for enhancement of chemotherapeutic efficacy in undifferentiated thyroid carcinomas.     

The fragile X in cattle

In search of an animal model for the human fragile X syndrome, the chromosomes of Holstein cows were examined. This breed was chosen because of previous studies on the baldy calf syndrome. An achromatic gap was observed at a specific site on the X chromosome closer to the centromere than that identified in humans. This unstained gap was found in 3%-4% of cells of the following four animals: an affected calf, her sister, their mother, and an unrelated Holstein cow. The bovine fragile X may not be analogous to the human fragile X but its location may be important as a genetic marker in linkage studies involving the loci for hypoxanthine phosphoribosyltransferase (HPRT) and glucose-6-phosphate dehydrogenase (G-6-PD).