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101.
The N-linked glycan g15 within the V3 loop of the HIV-1 external glycoprotein gp120 affects coreceptor usage,cellular tropism,and neutralization 总被引:8,自引:0,他引:8
We have studied infectivity and neutralization of X4, R5, and R5X4 tropic HIV-1 mutants, which are lacking N-linked glycosylation sites for glycans g13, g14, g15, and g17 in the V3 loop region of gp120. X4-tropic NL4-3 mutants lacking combinations of g14/15 or g15/17 showed markedly higher infectivity in CXCR4-specific infection. The role of g15 in CCR5-specific infection was investigated using viruses with high (NL-918, R5-monotropic), medium (NL-991, R5-monotropic), and low (NL-952, R5X4-dualtropic) CCR5-specific infectivity. For NL-991, a reduction of infectivity on GHOST-CCR5 cells was observed for a mutant lacking g15. For NL-952 mutants all lacking g15, a complete loss of CCR5-specificity was observed and NL-952 was shifted from R5X4 to X4 tropism. For all mutants of NL4-3, NL-991, and NL-952, where the lack of g15 markedly influenced infectivity or coreceptor usage, neutralization was enhanced. In contrast, NL-918 mutants with or without g15 showed no difference in neutralization and no difference in GHOST-CCR5 infection rates. Thus, for viruses with a low or medium CCR5-specificity the role of g15 for changing CCR5-usage and sensitivity to neutralization was more significant than for viruses with high infection rates on GHOST-CCR5 cells. Our data demonstrate that V3 glycans play an important role in the usage of CXCR4 and CCR5. The lack of g15 was relevant for a more efficient use of CXCR4, whereas interaction with CCR5 was facilitated in the presence of g15. This study also demonstrates that glycan g15 is involved in blocking of neutralizing antibodies and shifting HIV tropism from R5X4 to X4. 相似文献
102.
Relations between orienting response and span of immediate memory were studied by measuring skin potential responses (SPR) and heart rate (HR). Four conditions were studied by presenting letters in a tachistoscope and a 1000 cycle, 100 db tone simultaneous on some but not all trials. The conditions (15 Ss in each) were: tone and letters for 10 trials, then letters alone for 10 trials; tone and letters for 20 trials; only letters for 10 trials, followed by letters and tone for 10 trials; and only letters for 20 trials. The results showed: (1) positive SPR habituated and negative did not, (2) tone produced more SP activity, (3) HR showed a shift from acceleration to deceleration over 20 trials, but tone had no influence, (4) tone had no direct influence on span scores, (5) Ss showed improvement in number ol letters reported correctly. There was a significant correlation between span and negative SPR when tone was sounded (r =. 36). 相似文献
103.
104.
Klussmann JP Weissenborn SJ Wieland U Dries V Eckel HE Pfister HJ Fuchs PG 《Medical microbiology and immunology》2003,192(3):129-132
Human papillomavirus (HPV) infections are thought to be one of the causal factors in the development of head and neck squamous cell carcinomas (HNSCC), particularly in tumors arising from the Waldeyer's tonsillar ring. We screened 98 carefully stratified HNSCC and different control tissues for the presence of HPV DNA by nested polymerase chain reaction (PCR) specific for genital- and Epidermodysplasia verruciformis (EV)-associated HPVs and by HPV16-specific single step PCR. Typing was performed by direct sequencing and/or sequencing of cloned amplimers. On average HNSCC showed rather low HPV DNA prevalences; 18% of the oral cavity cancers, 8% of nasopharyngeal cancers, 25% of hypopharyngeal cancers and 7% of laryngeal cancers were HPV DNA positive. In contrast, HPV sequences could be detected in 45% of the oropharyngeal cancers, particularly tonsillar carcinomas (58%). Tonsillar carcinomas were significantly more likely to be HPV positive than tumors from any other site ( P<0.001). All tonsillar cancers contained oncogenic HPV types, predominantly HPV16 (13 of 14; 93%). Unaffected tonsils were available from two of these patients, but both tested negative for HPV DNA. Furthermore, no HPV DNA could be found in tonsillar biopsy specimens from control groups. Localization and load of HPV DNA was determined in HPV16-positive tonsillar carcinomas, their metastases and in unaffected mucosa using laser-assisted microdissection and subsequent real time fluorescence PCR. We demonstrated that the HPV genome is located in the cancer cells, whereas the infection of normal mucosa is a rare event. Quantification of HPV16 DNA in samples of seven patients yielded viral loads from 6 to 153 HPV DNA copies per beta-globin gene copy and the load values in both locations were roughly comparable. These loads are comparable with data shown for other HPV-associated lesions. Statistical evaluation of data related to clinicopathological parameters showed a significant correlation of the HPV positivity of tonsillar carcinomas with tumor grading ( P=0.008) and alcohol consumption ( P=0.029). Taken together our findings show a preferential association of HPV DNA with tonsillar carcinomas. Furthermore our results argue for HPV-positive tonsillar carcinomas representing a separate tumor entity, which is less dependent on conventional HNSCC risk factors. 相似文献
105.
106.
Reorganization of human cortical maps caused by inherited photoreceptor abnormalities 总被引:3,自引:0,他引:3
We describe a compelling demonstration of large-scale developmental reorganization in the human visual pathways. The developmental reorganization was observed in rod monochromats, a rare group of congenitally colorblind individuals who virtually lack cone photoreceptor function. Normal controls had a cortical region, spanning several square centimeters, that responded to signals initiated in the all-cone foveola but was inactive under rod viewing conditions; in rod monochromats this cortical region responded powerfully to rod-initiated signals. The measurements trace a causal pathway that begins with a genetic anomaly that directly influences sensory cells and ultimately results in a substantial central reorganization. 相似文献
107.
Identification of a novel coronavirus in patients with severe acute respiratory syndrome 总被引:1,自引:0,他引:1
Drosten C Günther S Preiser W van der Werf S Brodt HR Becker S Rabenau H Panning M Kolesnikova L Fouchier RA Berger A Burguière AM Cinatl J Eickmann M Escriou N Grywna K Kramme S Manuguerra JC Müller S Rickerts V Stürmer M Vieth S Klenk HD Osterhaus AD Schmitz H Doerr HW 《The New England journal of medicine》2003,348(20):1967-1976
108.
Michael M. Krausz Richard E. Justice Takayoshi Utsunomiya Herbert B. Hechtman 《Annals of biomedical engineering》1981,9(3):257-262
A simple system has been developed-for the prolonged infusion of an iced solution of prostacyclin (PGI2). In a 24 h period at pH 10, there is a theoretical loss in activity of 6%, while a 5 h infusion leads to a 2% reduction
in activity. The stability of the cooling system was demonstrated in six dog experiments where mean arterial pressure (MAP)
was reduced to 58±3.8 Torr (x±SEM) over a 5 h period of infusing 500 ng/kg/min. In a saline medium, at 3°C, a 5 h PGI2 infusion led to a stable reduction in MAP, whereas, at a temperature of 24°C, a 70 loss of infusate activity was noted.
Supported in part by The National Institute of Health, Grant No. GM24891-04; The U.S. Army Medical Research and Development
Command, Contract No. DAMD17-78-C-8026; The Brigham Surgical Group, Inc., and The Trauma Research Foundation. 相似文献
109.
H Nogami F Yoshimura D C Herbert T B Aufdemorte G A Gates G R Holt P J Sheridan 《The Anatomical record》1985,212(3):288-291
A quantitative autoradiographic immunocytochemical study was performed in which the nuclear uptake and retention of 3H-estradiol (3H-E2) by luteinizing hormone (LH) and prolactin (PRL) cells was examined in 19-21-year-old baboons. 3H-E2 concentrating cells were found in all of the three lobes of the pituitary in varying percentages (38.7%, pars distalis; 17.1%, pars intermedia; 6.3%, pars nervosa). Approximately 80% of PRL cells and nearly 100% of LH cells were labeled. A count of the number of silver grains over nuclei revealed a marked variation of the accumulation of 3H-E2 by LH cells and to a lesser extent in PRL cells. These results suggest functional heterogeneity among LH and PRL cells. The present results are discussed in relation to the physiological state of old animals. 相似文献
110.
Oskar Nuyken Gerhard Maier Aurelia Groß Herbert Fischer 《Macromolecular chemistry and physics.》1996,197(1):83-95
The termination reaction of the cationic polymerization of 2-phenyl- and 2-nonyl-2-oxazolines was examined by reacting the corresponding model oxazolinium salts having tosylate and trifluoromethansulfonate counterions with various nucleophiles. The reaction was monitored by 1H NMR spectroscopy. Piperidine and KOH react with the oxazolinium salts very fast and quantitatively. In the case of piperidine, the use of a double molar amount of piperidine is necessary to achieve complete conversion. The addition of piperidine, pyridine, 4-dimethylaminopyridine and morpholine takes place in position 5 of the oxazolinium ring, whereas water and KOH add in position 2. The rate of the termination reaction depends on the electron density of the nucleophile which can be correlated with the pKa value. With CF3SO as counterion the addition of nucleophiles in position 5 is distinctly faster, whereas the addition of water in position 2 is much slower than with TsO? as counterion. The ring-opening of the nonyl oxazolinium ion is slower than that of the phenyl oxazolinium ion. 相似文献