Formation of Ce-Si-O-N Glasses

The glass-forming region in the Ce-Si-O-N system was investigated. A large region of clear-glass formation was observed. The Ce:Si ratio of the clear-glass-forming region was consistent with that of the intergranular glassy phases in Ce-doped Si₂N₂O.     

Chemical nature of the light emitter of the Aequorea green fluorescent protein

The jellyfish Aequorea victoria possesses in the margin of its umbrella a green fluorescent protein (GFP, 27 kDa) that serves as the ultimate light emitter in the bioluminescence reaction of the animal. The protein is made up of 238 amino acid residues in a single polypeptide chain and produces a greenish fluorescence (lambda max = 508 nm) when irradiated with long ultraviolet light. The fluorescence is due to the presence of a chromophore consisting of an imidazolone ring, formed by a post-translational modification of the tripeptide -Ser65-Tyr66-Gly67-. GFP has been used extensively as a reporter protein for monitoring gene expression in eukaryotic and prokaryotic cells, but relatively little is known about the chemical mechanism by which fluorescence is produced. To obtain a better understanding of this problem, we studied a peptide fragment of GFP bearing the chromophore and a synthetic model compound of the chromophore. The results indicate that the GFP chromophore consists of an imidazolone ring structure and that the light emitter is the singlet excited state of the phenolate anion of the chromophore. Further, the light emission is highly dependent on the microenvironment around the chromophore and that inhibition of isomerization of the exo-methylene double bond of the chromophore accounts for its efficient light emission.     

Waveform degradation due to dispersion effects in an optical CPFSKsystem

Waveform degradation due to polarization and chromatic dispersion in a single-mode fiber is calculated for a coherent continuous-phase frequency-shift-keying (CPFSK) signal. Both kinds of dispersion distort the amplitude of the baseband signal and can limit transmission distance and capacity. For instance, polarization dispersion of 5 ps will restrict a bit rate by ~60 Gb/s when chromatic dispersion is fully reduced using a dispersion-shifted fiber or applying electrical equalization     

Peak shift characteristics for barium ferrite flexible disk drive

Output waveform and peak shift characteristics for low squareness Ba-ferrite perpendicular recording flexible disk (FD), the same as used for 3.5 inch Ba-ferrite 4MB FDD, were investigated by both calculation and measurement. A simple simulation for an isolated pulse and density responses was carried out and an estimation method for the perpendicular component factor, Kp, was derived. The peak shift characteristics and Kp for a Ba-ferrite FD were investigated for various recording /reproducing conditions, such as head gap length, recording current, etc. Then, it is shown that both the Kp value and peak shift are not so large, and therefore a phase equalizer is not needed for the low squareness Ba-ferrite FD.     

Synthesis of cationic surfactants with alkenyl group

Quaternary ammonium chlorides with long chain alkenyl groups were synthesized by the reaction of tert-amines with alkylallyl chloride which, in turn, were obtained by the allylic chlorination of 1-olefins with N-tert-butyl- or N-cyclohexyl-N-chloro-ethanesulfonamides. Of the two kinds of alkylallyl chlorides prepared by the allylic chlorination of 1-olefins, the γ-alkylallyl chlorides(I), were found to be reactive with tert-amines, while the secondary chlorides, α-alkylallyl chlorides(II), were not so reactive and, when the allylic chloride mixture was reacted with tert-amine under suitable reaction conditions, the γ-alkylallyl chloride could be selectively converted to a quaternary ammonium chloride while the α-alkylallyl chloride was recovered unreacted. The quaternary ammonium chlorides thus obtained were identified as γ-alkylallyl ammonium chlorides from their spectra, and they were shown to possess almost the same surface tension lowering ability as their saturated homologs, although larger critical micelle concentration values and greater water solubilities were observed.     

Altered peptide ligands trigger perforin- rather than Fas-dependent cell lysis

CTLs lyse Fas-expressing target cells by the concomitant action of a perforin- and a Fas-dependent mechanism. This study analyzed whether target cells pulsed with T cell antagonists and other altered peptide ligands (APLs) were susceptible selectively to only one of these two mechanisms. In vivo and in vitro activated T cells from transgenic mice expressing a TCR specific for lymphocytic choriomeningitis virus were used as effector cells. To distinguish between perforin- and Fas-dependent cytotoxicity, T cells from normal or perforin-deficient mice were used to lyse peptide-pulsed Fas-positive or Fas-negative target cells. In contrast to previous reports that have shown that APLs selectively induce the Fas-dependent pathway of cytotoxicity, our results demonstrate that target cells pulsed with T cell antagonists and other APLs are lysed predominantly by the perforin-dependent pathway. The contribution of Fas-mediated cytotoxicity was similar for the full agonist and the APLs. Thus, full agonists, partial agonists, and antagonists trigger similar and not distinct pathways of cytotoxicity.     

Construction, propagation, and titer estimation of recombinant adenoviruses carrying proapoptotic genes

Generation of a recombinant adenovirus (Adv) that induces the constitutive expression of an apoptotic gene has been extremely difficult owing to severe apoptotic damage to the host cell. In this study, 293 cells were transduced with the caspase-inhibiting CrmA gene (293-CrmA cells), and used as host cells to generate Adv carrying apoptosis-inducing genes (proapoptotic genes). The 293-CrmA cells proved to be highly efficient for the construction of recombinant Adv carrying genes encoding Fas and Fas ligand. Moreover, the 293-CrmA line produced an ample quantity of these recombinant viruses. Because the conventional 293 plaque formation assay did not reflect the actual number of cells infected with the Adv carrying the proapoptotic gene, a determination of the Adv DNA copy number introduced into target cells was necessary to evaluate the quantity of infective virus. The techniques described here should be widely applicable for the construction of a recombinant Adv, in ample quantity, and for the estimation of the quantity of recombinant Adv produced.     

Controlled trial of falecalcitriol versus alfacalcidol in suppression of parathyroid hormone in hemodialysis patients with secondary hyperparathyroidism

Since the first reports in the late 1950's, a large amount of data have been collected. The analysis of the main evidence from the major randomized trials will be analyzed in this paper according to preoperative, postoperative and chemoradiation approaches. Fifteen randomized preoperative trials were reported; they have been grouped according to the fractionation schedule. In the hypofractionation group (5 Gy for fraction), all five studies that delivered 3-5 doses in one week had a significant improvement in local control and one of them also showed improvement in survival. Operative mortality was higher in the radiotherapy arm if inadequate techniques had been applied. In 3 out of 8 studies with conventional fractionation there was a significant improvement in local control, but no impact in survival was detected. No studies with total dose lower than 34 Gy had an improvement in local control. None of the six randomized postoperative studies showed an improvement in local control or survival. In all trials the local control rate was uniform; ranging from 76% to 84%. Toxicity was higher in the radiotherapy arm. One preoperative and five postoperative randomized studies that used chemoradiation were analyzed. One postoperative chemoradiation study showed a significant improvement in survival in comparison to the surgery arm, and another showed the same advantage compared to the postoperative arm. Protracted infusional administration of 5FU concomitant to radiotherapy showed better survival than bolus administration. No advantages were shown in using MeCCNU or Levamisole in two studies. Toxicity was high and related to the dose and the modality of administration of the drugs in order to adequately treat the different stages of rectal cancer, patients must be carefully selected in order to prescribe the most effective and the least toxic treatment for the individual stage; organ preservation should be an essential goal for its impact on quality of life, and the cost estimates should be taken into account.     

Combination chemotherapy with cis-platinum and ifosfamide for hormone unresponsive prostate cancer

PURPOSE: There is no effective therapy against hormone refractory prostate cancer. This led us to evaluate the effectiveness and toxicity of cis-platinum (CDDP) and ifosfamide (IFM) combination chemotherapy in the patients with hormone-unresponsive carcinoma of the prostate. METHODS: Patients with hormone-unresponsive prostate cancer were scheduled to receive CDDP 70 mg/m2 intravenously on day 1 and IFM 1.2 g/m2/day intravenously on day 1 through day 5 of 28-day cycle. RESULTS: Twenty seven patients with hormone unresponsive prostate cancer were enrolled onto this trial. Of these patients, seven (26%) demonstrated a partial objective response (PR), and ten (37%) a stable disease (ST). The response duration of PR cases lasted from 6 to 49 months with a median of 16 months and the response duration of PR + ST cases lasted from 3 to 36 months with a median of 10 months. Subjective improvement was obtained in 11 patients (41%). Survival duration of all cases were 4 to 89 months with a median of 23 months and probabilities of survival at 3 years and 5 years were 36% and 24%, respectively. The toxicity of this treatment was mostly mild to moderate, anemia (96%), leukocytopenia (89%), anorexia (81%), alopecia (67%), thrombocytopenia (44%), hematuria (38%), renal dysfunction (19%) and liver dysfunction (7%) were noticed. Severe toxicity was observed in two cases, one acute renal failure and one endotoxin shock. CONCLUSION: We conclude that CDDP and IFM combination chemotherapy was active regimen for hormone unresponsive prostate cancer.