A novel Plasmodium falciparum sporozoite and liver stage antigen (SALSA) defines major B, T helper, and CTL epitopes

In the search for subunit vaccines that are able to induce the type of sterile, protective immunity achieved by irradiated sporozoites, there is increasing evidence that defense mechanisms directed at the intrahepatic stage and Ags expressed at this stage are critical. We have initiated a systematic search for such molecules and report here the identification and partial characterization of a novel Plasmodium falciparum gene encoding a 70-kDa protein, expressed in both sporozoite and liver stages (SALSA), with a vaccine potential that stems from its antigenic features. Antigenicity and immunogenicity studies were conducted in individuals exposed to malaria, in immunized mice, and in chimpanzees, using a recombinant protein and two synthetic peptides. Results show that the SALSA nonrepetitive sequence defines 1) major B cell epitopes, as shown by a high prevalence of Abs to each peptide in three African areas differing in their level of endemicity; 2) Th epitopes, as demonstrated by lymphoproliferation and IFN-gamma secretion in cells from the individuals from one of the low transmission areas, as well as helper effect upon Ab secretion in mice; and 3) epitopes for cytolytic lymphocytes, demonstrated in immunized and sporozoite-challenged chimpanzees, and associated with MHC class I leukocyte Ags. The latter are of particular importance, because this is the only part of the malaria life cycle in which the parasite is located in a cell expressing class I Ags and because CD8+ lymphocytes were found to be responsible for protection in experimental models.     

Very small wide-band MMIC magic T's using microstrip lines on athin dielectric film

An MMIC magic T (180° hybrid circuit) using microstrip lines on a thin silicon oxynitride (SiON) dielectric film is proposed. The microstrip-line area reduction is achieved by using thin-film microstrip lines, derived from the thin substrate structure, that have very narrow linewidths. The area is effectively minimized using meanderlike configurations. The SiON thin film is deposited by low-temperature plasma CVD (chemical vapor deposition). The MMIC magic T has been designed for a center frequency of 12 GHz, and small size with wideband performance from 6 GHz to 18 GHz has been achieved. Thus, magic T's using thin-film microstrip lines are promising for miniaturized high-performance MMICs, such as balanced mixers and modulators     

Severe hemolytic anemia with tear drop red cells as initial manifestation of Wilson's disease

A 16-year-old girl was admitted for a detailed examination of hemolytic anemia in November 1995. Initial laboratory findings included a total bilirubin concentration of 1.46 mg/dl, hemoglobin of 9.1 g/dl, and a reticulocyte count of 89/1000 percent. The plasma haptoglobin concentration was below 10 mg/dl. A blood smear showed many dacryocytes and a few echinocytes and codocytes. GOT was 71 IU/l; GPT, 44 IU/l; and LDH, 812 IU/l; the results of a hepaplastin test were 45% of normal. On further investigation, the level of serum ceruloplasmin was found to be 4 mg/dl, and of serum copper, 43 micrograms/dl. Urinary copper excretion was markedly increased, at 345 micrograms per day. Slit-lamp examination of both corneas revealed obvious Kayser-Fleischer rings. A liver biopsy sample showed fibrosis histologically and an elevated copper concentration of 535 micrograms/g dry weight and 183 micrograms/g wet weight. In family studies, the patient's asymptomatic 5-year-old sister was observed to have metabolic abnormalities consistent with Wilson's disease. These findings suggested that the patient's hemolytic anemia with red cell deformities was due to abnormal copper metabolism associated with Wilson's disease.     

Comparative field study on precipitation, throughfall, stemflow, fog water, and atmospheric aerosol and gases at urban and rural sites in Japan

Precipitation collected by a wet-only sampler (WP), precipitation collected by a filtering-type bulk sampler (BP), throughfall (TF), stemflow (SF), fog water (FW), and atmospheric aerosol and gases were collected at two sites with different site classifications: an urban site (Mt. Rokko) and a rural site (Mt. Awaga) to investigate canopy-atmosphere interactions and to study the chemistry of precipitation in forested areas located in different atmospheric conditions. Compared to those at the rural site, the monthly volume-weighted pH values at the urban site were not significantly (p>0.05) different for WP, higher (p<0.05) for BP, not significantly (p> 0.05) different for TF, lower (p<0.01) for SF, and lower (p<0.01) for FW. The order of mean pH values at the urban site was FW相似文献   

Site-directed mutagenesis of recombinant equine chorionic gonadotropin/luteinizing hormone: differential role of oligosaccharides in luteinizing hormone- and follicle-stimulating hormone-like activities

Equine chorionic gonadotropin (eCG) consists of highly glycosylated alpha- and beta-subunits and belongs to the glycoprotein hormone family that includes LH and FSH. eCG is a unique member of the gonadotropin family because it elicits response characteristics of both FSH and LH in other species than the horse. To determine the biological role of the N-linked oligosaccharide at Asn 56 of the alpha-subunit and O-linked oligosaccharides at the carboxyl-terminal peptide (CTP) of the beta-subunit, two mutant eCGs, in which Asn 56 of the alpha-subunit was replaced with Gln (eCG alpha 56/beta) or CTP was deleted (eCG alpha/ beta-CTP), were produced by site-directed mutagenesis and transfecting chinese hamster ovary (CHO-K1) cells. LH- and FSH-like activities were assayed in terms of testosterone production and aromatase activity in primary cultured rat Leydig cells and granulosa cells, respectively. The wild type eCG showed similar LH- and FSH-like activities to native eCG in the in vitro bioassays. The LH-like activity of eCG alpha 56/beta was greatly reduced, whereas that of eCG alpha/beta-CTP was unaffected, demonstrating that the oligosaccharide at Asn 56 of the alpha-subunit of eCG plays an indispensable role in LH-like activity. Interestingly, the FSH-like activity of eCG alpha 56/beta was increased markedly in comparison with the wild type, and that of eCG alpha/beta-CTP was also considerably increased. These data indicate that the dual activities of eCG, LH- and FSH-like activities, could be separated by removal of the N-linked oligosaccharide on the alpha-subunit Asn 56 or CTP-associated O-linked oligosaccharides.     

Oxidative coupling polymerization of octahydroxyquaternaphthyl derivatives producing stereocontrolled polybinaphthol

Summary The oxidative coupling polymerization of the novel quaternaphthyl monomers, such as (S,S,S)-3,3”’-dihydroxy-2,2’,3’,2”,3”2”’-hexamethoxy-1,1’:4’,1”:4”,1”’-quarter-naphthyl and (S,S,S)-3’,2”-dibenzyloxy-3,3”’-dihydroxy-2,2’,3”2”’-tetramethoxy-1,1’:4’,1”:4”,1”’-quaternaphthyl, with the copper(I) chloride-(S)-2,2’-isopropyridene-bis(4-phenyl-2-oxazoline) catalyst was performed. The obtained polybinaphthol derivatives consisted of about 20 repeating naphthalene units and the stereochemical composition of up to an 88% enantiomer excess (S).     

Colorimetric detection of Mn(ii) based on a mixture of an anionic pyridylazo dye and a cationic polyelectrolyte in aqueous solution

We have developed a simple and valuable method for the construction of a colorimetric chemosensor for detecting Mn(ii ) in aqueous media. The chemosensor was prepared by mixing two commercial products, an anionic organic dye, 2‐(5‐nitro‐2‐pyridylazo)‐5‐(N‐propyl‐N‐sulphopropylamino)phenol (Nitro‐PAPS) and a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC). Upon gradual addition of Mn(ii ) to the chemosensor, the absorption spectra showed a remarkable bathochromic shift concomitantly with a distinct colour change from yellow to blue‐green, while Nitro‐PAPS alone could not detect Mn(ii ) in a colorimetric method. PDADMAC played a key role in sensing Mn(ii ) for the mixture. The colour change might be due to the formation of the aggregate obtained through electrostatic interactions of a Nitro‐PAPS‐based Mn(ii ) complex with PDADMAC. This investigation can inform the development of a new chemosensor by the combination of an anionic dye and a cationic polyelectrolyte.     

Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP‐Gold Complexes and Chiral Anions

A synergistic effect is observed for the combination of a neutral dinuclear gold complex with a chiral silver phosphate in the intramolecular hyroalkoxylation of allenes to give furan derivatives in high yields and enantioselectivities. The monocationic dinuclear gold complex affords higher catalytic activity and enantioselectivity than the neutral or dicationic digold complexes. The synergistic effect is thus highly promising to provide a guiding principle in designing an efficient chiral environment for creating an asymmetric catalyst.