Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells.

We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, and compared with theoretical calculations accounting for interband and intersubband photoexcitations. The extra photocurrent caused by the two-step photoexcitation was maximal for a reversely biased electric field, while the current generated by the interband photoexcitation increased monotonically with increasing electric field intensity. The internal electric field in solar cells separated photogenerated electrons and holes in the superlattice (SL) miniband that played the role of an intermediate band, and the electron lifetime was extended to the microsecond scale, which improved the intersubband transition strength, therefore increasing the two-step photocurrent. There was a trade-off relation between the carrier separation enhancing the two-step photoexcitation and the electric-field-induced carrier escape from QDSLs. These results validate that long-lifetime electrons are key to maximising the two-step photocarrier generation in QDSL-IBSCs.

Carbon monoxide protects rat lung transplants from ischemia-reperfusion injury via a mechanism involving p38 MAPK pathway.

Carbon monoxide (CO) provides protection against oxidative stress via anti-inflammatory and cytoprotective actions. In this study, we tested the hypothesis that a low concentration of exogenous (inhaled) CO would protect transplanted lung grafts from cold ischemia-reperfusion injury via a mechanism involving the mitogen-activated protein kinase (MAPK) signaling pathway. Lewis rats underwent orthotopic syngeneic or allogeneic left lung transplantation with 6 h of cold static preservation. Exposure of donors and recipients (1 h before and then continuously post-transplant) to 250 ppm CO resulted in significant improvement in gas exchange, reduced leukocyte sequestration, preservation of parenchymal and endothelial cell ultrastructure and reduced inflammation compared to animals exposed to air. The beneficial effects of CO were associated with p38 MAPK phosphorylation and were significantly prevented by treatment with a p38 MAPK inhibitor, suggesting that CO's efficacy is at least partially mediated by activation of p38 MAPK. Furthermore, CO markedly suppressed inflammatory events in the contralateral naïve lung. This study demonstrates that perioperative exposure of donors and recipients to CO at a low concentration can impart potent anti-inflammatory and cytoprotective effects in a clinically relevant model of lung transplantation and support further evaluation for potential clinical use.

Identification of a small tetraheme cytochrome c and a flavocytochrome c as two of the principal soluble cytochromes c in Shewanella oneidensis strain MR1.

Two abundant, low-redox-potential cytochromes c were purified from the facultative anaerobe Shewanella oneidensis strain MR1 grown anaerobically with fumarate. The small cytochrome was completely sequenced, and the genes coding for both proteins were cloned and sequenced. The small cytochrome c contains 91 residues and four heme binding sites. It is most similar to the cytochromes c from Shewanella frigidimarina (formerly Shewanella putrefaciens) NCIMB400 and the unclassified bacterial strain H1R (64 and 55% identity, respectively). The amount of the small tetraheme cytochrome is regulated by anaerobiosis, but not by fumarate. The larger of the two low-potential cytochromes contains tetraheme and flavin domains and is regulated by anaerobiosis and by fumarate and thus most nearly corresponds to the flavocytochrome c-fumarate reductase previously characterized from S. frigidimarina to which it is 59% identical. However, the genetic context of the cytochrome genes is not the same for the two Shewanella species, and they are not located in multicistronic operons. The small cytochrome c and the cytochrome domain of the flavocytochrome c are also homologous, showing 34% identity. Structural comparison shows that the Shewanella tetraheme cytochromes are not related to the Desulfovibrio cytochromes c(3) but define a new folding motif for small multiheme cytochromes c.

High galactosylation of oligosaccharides in umbilical cord blood IgG, and its relationship to placental function.

N-linked oligosaccharides on human serum IgGs have been reported to modulate IgG function. We studied umbilical cord blood to determine whether neonatal IgGs have characteristic structures related to developmental and pathological status. Oligosaccharide patterns of serum IgG from 45 umbilical cord blood samples were characterized by HPLC, and compared with those of serum IgG from 11 normal adults. Oligosaccharyl amines from purified IgG were released by recombinant N-glycanase, labeled with fluorescence reagent FMOC (9-fluorenylmethyl chloroformate), and analyzed quantitatively by high-pressure liquid chromatography (HPLC). Increased galactosylation was observed in cord blood. The ratio of galactosylated to non-galactosylated oligosaccharides on IgG was 7.90+/-3.92 (mean+/-S.D.) in cord blood, significantly higher than the ratio in adults (1.60+/-0.62, P<0.0001). There were weak but not significant correlations between the ratio and birth weight, gestation period, mother's age, and no correlation with serum IgG concentration. The ratio was lower for premature or intra-uterine growth retarded neonates. Our results, in conjunction with previous reports that galactosylated IgG stimulates Fc-mediated phagocytosis of monocytes, suggest that increased galactosylation of IgG enhances neonatal immunity.

[Fluorescence detection in capillary electrophoresis: detector cell].

A newly developed fluorescence detector cell for capillary electrophoresis was described. Detection of analytes having fluorescence is performed in an on-capillary mode with a xenon are lamp. A grating monochromator was used for the selection of the excitation wavelength. Fluorescence emission was monitored by collection of light from the capillary using a newly devised detector cell positioned at right angle to the excitation beam. Emission wavelengths were isolated using a filter and amplified with a photomultiplier. The detection limits obtained using the newly devised detector cell for amino acids and carbohydrates labeled with a fluorescent reagent were compared with that obtained using a conventional quartz detector cell. The results indicated that 100 nM and 4 microM of amino acids and oligosaccharides labeled with 9-fluorenymethyl chloro-formate and 2-aminopyridine, respectively, could be detected with the newly devised detector cell, in contrast to no signals with the conventional quartz detector cell. The separation and detection of fluorescent derivatives of amino acids, peptides, monosaccharides and oligosaccharides were also performed and an appropriate linearity was observed in a detector response of the samples within the constant concentration.

Intraoperative radiotherapy for resectable extrahepatic bile duct cancer.

PURPOSE: Through a retrospective study of intraoperative radiation therapy (IORT) in bile duct cancer, we hope to help clarify its clinical usefulness. METHODS AND MATERIALS: Between 1976 and 1996, IORT was carried out in 35 patients with bile duct cancer at the Tokyo Metropolitan Komagome Hospital. Of the 35 patients, resection proved to be curative in 15. Intraoperative irradiation of 15-30 Gy (average 20.1 Gy) was delivered by electron beam in the 5- to 19-MeV energy ranges. Postoperative external-beam radiation therapy (EBRT) was also delivered in 16 patients. The EBRT was fractionated to 2 Gy/day, in principle, and was delivered at 8.8-54 Gy (average 40.4 Gy) by 10-MV X-rays. RESULTS: The median survival in our patients was 19 months. The 1-year, 2-year, and 5-year survival rates were 57%, 43%, and 19%, respectively. Statistical analysis identified the following prognostic factors: performance status, curative surgical resection, lymph node metastasis, IORT dosage, and treatment period. Only 1 patient (3%) died within 30 days after surgery, and the incidence of late-onset complications was 21%. CONCLUSION: The combination of IORT and EBRT is useful for patients with bile duct cancer who undergo noncurative resection or who have lymph node metastasis.

Radiation therapy for stage I and II testicular seminoma: changes in the treatment policy for the prescribed dose.

BACKGROUND: We set out to review treatment policy, survival rate and acute and late sequelae of histologically confirmed seminoma patients who underwent orchiectomy and radiation therapy. MATERIALS AND METHODS: Thirty patients with testicular seminoma were investigated. The follow-up ranged from 1-20 years, with a median of 8.6 years. There were 23 patients with Stage I, six with Stage IIA and one with Stage IIB of the disease. All patients were treated with orchiectomy followed by iliac and paraaortic irradiation (median dose: 3900cGy for Stage I and 4000 cGy for Stage II patients). Up to 1986 the median total dose was 40Gy, and this dose was administered to sixteen patients. After that, fourteen patients received a total dose of 32Gy. RESULTS: For patients with Stage I and Stage II, 5- year disease-free survival rate was 100%. Twenty-three patients experienced certain acute reactions or side effects and all became well after radiation therapy; however, almost no patients showed severe late complications. CONCLUSION: In our study, radical orchiectomy and postoperative irradiation of iliac and paraaortic lymphaticus give good results for patients with Stage I and II testicular seminoma.

Radiotherapy for osseous metastases from hepatocellular carcinoma: a retrospective study of 57 patients.

OBJECTIVE: We undertook to evaluate the therapeutic effects of radiotherapy in patients with bone metastases from hepatocellular carcinoma (HCC), identify prognostic factors, and find an optimum radiation schedule. METHODS: We retrospectively analyzed the clinical records of 57 patients (99 sites) with painful bone metastases from HCC from December 1978 to March 1997. Their ages ranged from 51 to 82 yr (mean, 62 yr), and the male:female ratio was 49:8. Among them, there were nine patients (16%) with metastases to other organs. Twenty patients (35%) had a solitary bone metastasis and 37 (65%) had multiple bone metastases. The total radiation dose ranged from 20 to 65 Gy (mean, 43 Gy) and that of the Time, Dose, and Fractionation Factor (TDF) values (per explanation given in text) ranged from 35.2 to 118.2 (mean, 73.2). RESULTS: Pain relief was obtained for 83.8% (83/99) of bone metastases from HCC. Those with a TDF value of > or = 77 (a TDF value of 77 is nearly equal to 48 Gy administered in fractions of 2 Gy each daily or 39 Gy administered in fractions of 3 Gy each daily), responded better than those with a TDF value of < 77 (p < 0.05). Overall, the median survival time from the start of radiotherapy was 179 days (6 months). Patients with a solitary bone metastasis and those without metastases to other organs had a better prognosis (p < 0.05 for both subgroups). CONCLUSIONS: Radiation therapy was effective for bone metastases from HCC, especially for those treated with a TDF value of > or = 77.

[Hepato-biliary excretion of water-soluble iodinated contrast medium shortly after abdominal angiography].

Thirty-nine patients underwent CT examination 15 to 30 min after abdominal angiography with ioxaglate. Gallbladder opacification was observed in 15 patients in the absence of clinical evidence of renal impairment. Among them, 14 patients revealed liver cirrhosis or chronic hepatitis, and one patient showed severe fatty liver on CT. The amount of contrast medium used varied from 70 ml to 310 ml (mean 180 ml). There was no significant relationship between visualization of the gallbladder and the total dose of ioxaglate or presence of liver dysfunction, which indicated that gallbladder opacification was not a rare phenomenon on CT shortly after abdominal angiography with a normal dose of ioxaglate. Gallbladder opacification on CT examination shortly after abdominal angiography shows that the hepatobiliary tract is important in the excretion of ioxaglate.

Gallbladder visualization on CT shortly after angiography with ioxaglate.

Thirty-five patients underwent CT examination 15 to 30 min after abdominal angiography with ioxaglate. The gallbladder was visualized in 12 patients in the absence of clinical evidence of renal impairment. Gallbladder opacification on CT examinations shortly after angiography shows that the hepatobiliary tract is important in the excretion of ioxaglate.

A series of disialogangliosides with binary 2----3 sialosyllactosamine structure, defined by monoclonal antibody NUH2, are oncodevelopmentally regulated antigens.

A mouse IgM monoclonal antibody, NUH2, was raised after immunization of mice with the disialoganglioside fraction of human colonic adenocarcinoma. This antibody reacts specifically with disialogangliosides having the Structure 1 shown below. (formula; see text) NUH2 does not react with structures lacking the sialic acid at either the beta 1----3 or beta 1----6 side chain, nor with a binary structure having unequal chain lengths, nor with a binary type 2 chain structure having a trimannosyl core as found in the side chain of N-linked complex type oligosaccharides. (formula; see text) In humans, the disialoganglioside antigens defined by antibody NUH2 are present in low quantity in normal cells (e.g., erythrocytes) and tissues, but are expressed highly in some colonic cancers, placenta, trophoblast, and sperm, and can be regarded as oncodevelopmentally regulated antigens.

Application of Namalva interferon-alpha monoclonal antibodies for purification and enzyme immunoassay of interferon-alpha.

Namalva (or Namalwa) interferon (IFN)-alpha was partially purified using a combination of conventional methods and modified acid-ethanol extraction. Four mouse monoclonal antibodies against Namalva IFN-alpha were prepared by hybridoma technology after immunization with Namalva IFN-alpha thus purified. Three of these monoclonal antibodies recognized the same or a similar epitope on Namalva IFN-alpha. One of these antibodies was paired with the fourth recognizing a different epitope and used respectively as enzyme-conjugated antibody and solid-phase antibody in our one step enzyme immunoassay (EIA) for IFN-alpha. This assay is simple and was able to detect as little as 5 pg of IFN-alpha in 100 microliters of sample in the short time of 5 hr. There was a good correlation between the EIA and bioassay. The use of one of the monoclonal antibodies as an immunoadsorbant to purify Namalva IFN-alpha is also described.

Human sperm carbohydrate antigens defined by an antisperm human monoclonal antibody derived from an infertile woman bearing antisperm antibodies in her serum.

The epitope structure of the human sperm antigen reacting with antibodies present in sera of infertile women has been studied using mAb H6-3C4, which produces immobilization of human sperm in the presence of complement. Another antibody, NUH2, which also induces human sperm immobilization, was used to substantiate the presence of a receptor on sperm involved in susceptibility to immobilization. Both antibodies defined type 2 chain polylactosamine structure. H6-3C4 is directed to internally located repetitive N-acetyllactosamine, i.e., sialyl-i, i, or fucosyl-i. NUH2 defines binary alpha 2----3 sialyl type 2 chain, i.e., sialyl-I. Thus, the presence of antibodies in the sera of infertile women directed to sperm lactosaminoglycan or lactosaminolipid could be the basis for infertility in these cases.

Expression of LeY and extended LeY blood group-related antigens in human malignant, premalignant, and nonmalignant colonic tissues.

The LeY determinant, a difucosylated type 2 blood group-related antigen, is a positional isomer of the Leb blood group antigen and a fucosylated derivative of the LeX antigen. The LeX antigen behaves like an oncodevelopmental tumor-associated antigen in human colon cancer, and extended polyfucosyl LeX antigens are more specific for colon cancer tissues than are simple, monofucosyl LeX antigens. The present investigation compared the expression of simple and extended LeY antigens in a variety of malignant and nonmalignant human colonic tissues to gain insight into the normal distribution and cancer-associated expression of these antigens. Monoclonal antibody AH-6, which recognizes the LeY epitope irrespective of its carrier carbohydrate chain, stained the majority of specimens regardless of malignant potential or location within the colon. In contrast, CC-1 and CC-2 monoclonal antibodies, which recognize extended LeY structures, and KH-1, which is specific to trifucosyl LeY, preferentially stained malignant colonic tissues and rarely stained normal colonic mucosae. Mucosa immediately adjacent to cancer usually stained with AH-6 but not with KH-1, CC-1, or CC-2. Extended or trifucosyl LeY antigen expression was limited exclusively to premalignant (adenomatous) polyps and was invariably absent from nonpremalignant (hyperplastic) polyps. Moreover, among adenomatous polyps, extended LeY antigen expression tended to correlate with three parameters of malignant potential: larger polyp size; villous histology, and severe dysplasia. AH-6 failed to distinguish between hyperplastic and adenomatous polyps. In second-trimester fetal colonic mucosa, AH-6 bound to both proximal and distal segments whereas KH-1, CC-1, and CC-2 bound only to proximal segments. We conclude that in human colon, the LeY hapten is an oncodevelopmental cancer-associated antigen and extended LeY antigens are highly specific markers for malignancy and premalignancy.

Novel fucolipids of human adenocarcinoma: characterization of the major Ley antigen of human adenocarcinoma as trifucosylnonaosyl Ley glycolipid (III3FucV3FucVI2FucnLc6).

A series of glycolipid antigens with Ley determinant (Fuc alpha 1----2Gal beta 1----4(Fuc alpha 1----3)GlcNAc) defined by monoclonal antibody AH6 (Abe, K., McKibbin, J. M., and Hakomori, S. (1983). J. Biol. Chem. 258, 11793-11797) have been detected in human colonic carcinoma cases. Three Ley-active components have been identified as follows. The simplest compound was characterized as Ley hexaosylceramide (lactodifucohexaosylceramide, III3FucIV2FucnLc4), which was previously isolated and was found as the major component in six out of eight cases of colonic adenocarcinoma but as only a very minor component in two cases. The second component was a very minor component in all eight cases, and its structure was identified by 1H NMR spectroscopy as an extended Ley (lactodifucooctaosylceramide, V3FucVI2FucnLc6; Structure 1 below). The third, major component, common in all eight cases, has been identified as trifucosyl Ley (lactotrifucononaosylceramide, III3FucV3FucVI2FucnLc6, Structure 2 below) based on 1H NMR spectroscopy, methylation analysis, and direct-probe electron-impact mass spectrometry. (formula; see text)

Novel fucolipids of human adenocarcinoma: monoclonal antibody specific for trifucosyl Ley (III3FucV3FucVI2FucnLc6) and a possible three-dimensional epitope structure.

Immunization of mice with Ley-active trifucosylnonaosylceramide (III3FucV3FucVI2FucnLc6) isolated from human colonic adenocarcinoma (Nudelman, E., Levery, S. B., Kaizu, T., and Hakomori, S. (1986) J. Biol. Chem. 261, 11247-11253) followed by selection of hybridoma by positive reaction with this antigen and negative reaction with two other Ley antigens (III3FucIV2FucnLc4 and V3FucVI2FucnLc6) resulted in successful isolation of the hybridoma producing IgM antibody, termed KH1, specific to Ley-active trifucosylnonaosylceramide, which does not cross-react with Ley-active hexaosyl- or octaosylceramides (III3FucIV2FucnLc4 and V3FucVI2FucnLc6) without internal fucosyl substitution. The three-dimensional structure of the trifucosylnonaosylceramide was simulated based on previously published glycosidic torsion angles for fucosyl type 2 chain (Lex and Ley) and for GlcNAc beta 1----3Gal beta as predicted by hard sphere exo-anomeric calculations (Thøgersen, H., Lemieux, R. U., Bock, K., and Meyer, B. (1982) Can. J. Chem. 60, 44-57). The picture thus constructed showed a broad nonpolar area consisting of the hydrophobic surface of the pyranosyl ring and acetamido group of N-acetylglucosamine and three CH3 groups of L-fucose; this hydrophobic area is adjacent to a hydrophilic area. In analogy to the detailed structure of Leb or Ley involved in their interactions with antibodies and lectins (Spohr, U., Hindsgaul, O., and Lemieux, R. U. (1985) Can. J. Chem. 63, 2644-2652), such a wide hydrophobic area adjacent to a hydrophilic region could be recognized by the antibody KH1, as shown in the model illustrated in the text. Since the axis of ceramide, which is inserted in the lipid bilayer, is perpendicular to the plane of type 2 chain, the epitope recognized by the antibody KH1 is located at the external nonpolar surface of the carbohydrate chain that is overlaid on the lipid bilayer.