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1.
In the preceding paper, an alternative method is described for obtaining information about the reorientational behavior of a fluorophore in a membrane system from frequency domain measurements. To demonstrate this new analysis procedure, we present data for the probe-molecule 1,6-diphenyl-1,3,5-hexatriene (DPH) in l--dimyristoyl- and l--dipalmitoylphosphatidylcholine (DMPC and DPPC) obtained with two different phase fluorometers: the SLM 4800A Subnanosecond Spectrofluorometer which has only three fixed frequencies available (6, 18 and 30 MHz) and the recently constructed continuously variable multifrequency phasefluorometer (Gratton and Limkeman 1983).It will be shown that reasonable information about the anisotropy behavior of a fluorophore can be obtained even if only three frequencies are used. The phase modulation technique was also used to check the new expression for the anisotropy, r(t), called the general model and introduced by Van der Meer et al. (1984). The parameters P 2, P 4 and D, obtained from the nonlinear least squares fit (Bevington 1969) for this general model, confirm the results from the pulse technique of Ameloot and coworkers (Ameloot et al. 1984; Pottel et al. 1986).  相似文献   
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Highly purified plasma membranes of bovine thyroid were obtained by differential pelleting followed by discontinuous gradient centrifugation in a swing-out rotor. Subfractions of plasma membranes were prepared by affinity chromatography on Con A-Sepharose. The final membrane fractions were enriched 25-30-fold over homogenate in 5'-nucleotidase and alkaline phosphatase and displayed a protein to phospholipid ratio of 1.67 and a cholesterol to phospholipid molar ratio of 0.55. The phospholipid composition did not deviate appreciably from that of whole tissue except for the higher sphingomyelin level (22.5 vs. 14.0%). The predominant fatty acids were palmitic (16:0), oleic (18:1), stearic (18:0) and linoleic (18:2) acid. The physical state of the membrane was studied by (i) calculation of the lipid structural order parameter SDPH from steady-state fluorescence anisotropy determinations of the hydrophobic probe 1,6-diphenyl-1,3,5-hexatriene (DPH); (ii) estimation of the lateral diffusion coefficient of pyrene following excimer formation. These parameters were determined in native thyroid plasma membranes and in reconstituted vesicles, obtained by detergent dialysis from octylglucoside solubilized membrane components. The presence of membrane protein or neutral lipids induced more restraint on the movements of the fluorophores. The lipid order parameter, SDPH was mainly determined by the neutral lipids. Subfractions of plasma membrane enriched in luminal membranes have a slightly lower fluidity (higher SDPH and lower Ddiff values) than subfractions enriched in basolateral membranes. This difference appears to be due to both differences in lipid as well as protein composition. Under physiological conditions, no significant alterations in probe dynamics could be observed upon addition of thyrotropin or cholera toxin, even at micromolar concentrations.  相似文献   
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OBJECTIVE--To examine the effect of eradication of Helicobacter pylori on symptoms of non-ulcer dyspepsia. DESIGN--Four week prospective study. SETTING--One hospital outpatient and endoscopy department. PATIENTS--90 adults with persistent symptoms typical of non-ulcer dyspepsia but no clinical or endoscopic evidence of other peptic, biliary, pancreatic, or malignant disease; all had histological and microbiological evidence of infection with H pylori. 83 patients completed the treatment regimen. INTERVENTION--Colloidal bismuth subcitrate 120 mg four times a day for four weeks (27 patients); metronidazole 400 mg and amoxycillin 500 mg each three times a day for one week (27); and bismuth subcitrate 120 mg four times a day for four weeks, metronidazole 400 mg three times a day for one week, plus amoxycillin 500 mg three times a day for the first week (29). MAIN OUTCOME MEASURES--Change in symptom scores determined with questionnaire; histological evidence of gastritis and microbiological evidence of presence of H pylori in biopsy specimens. RESULTS--Overall, H pylori was eradicated in 41 (49%) patients. Although gastritis scores improved significantly in only patients in whom H pylori had been eradicated (from 1.56 to 0.61, p less than 0.01 v from 1.83 to 1.07, p = 0.52) mean symptom scores after treatment were similar in patients in whom H pylori had or had not been eradicated (3.0 v 2.3, NS). Similarly the mean symptom score improved whether or not gastritis improved (2.8 v 3.1 respectively, p = 0.72). The observations were similar for treatment groups analysed individually. CONCLUSION--Antral infection with the organism does not seem to have an important aetiological role in non-ulcer dyspepsia short term.  相似文献   
5.
As part of a large survey on reservoirs of Lassa fever in Guinea, three villages were investigated in high endemic zone, close to Sierra Leone border. Biodiversity of the small mammal community is presented in this study through a standardized trapping in houses, cultivations and forest. Identification of the small mammals was based on morphology and by molecular technique for sibling species. Of the 1123 specimens collected in 2003–2005, we identified seventeen species (thirteen Muridae, four Soricidae), leading to high diversity (Shannon index = 1.6–1.8) and high equitability (evenness index = 0.7–0.8) in cultivations and forest. In houses conversely, the rodent community was dominated by Mastomys natalensis (95–98%), leading to low diversity and equitability. Dynamics and reproduction were investigated in two species of pygmy mice, Mus mattheyi and Mus minutoides, two species of Praomys, P. daltoni and P. rostratus, and in Mastomys erythroleucus. The pygmy mice were abundant in cultivations in early rainy season, and reproduced from rainy to dry season. Praomys daltoni was also found more abundant in cultivations and seemed to reproduce between rainy and dry season, whereas P. rostratus preferred forest and cultivations in late rainy season, and reproduced throughout the year. Finally, M. erythroleucus was more abundant in forest in dry season, and seemed to reproduce from late rainy to dry season. This species had a low occurrence (6.5%) in the Faranah’s zone, and probably lived at its southern limit in Guinea. The presence of other Murinae, such as M. natalensis, Praomys spp as possible competitors in the same habitats, is discussed. For the first time, this study relates population biology of pygmy mice with molecular identification.  相似文献   
6.
Mycobacterium tuberculosis complex (MTBC) comprises closely related species responsible for human and animal tuberculosis (TB). Efficient species determination is useful for epidemiological purposes, especially for the elucidation of the zoonotic contribution. In Algeria, data on MTBC genotypes are largely unknown. In this study, we aimed to investigate the occurrence and diversity of MTBC genotypes causing human and bovine TB in Northern Algeria. During a two-year sampling period (2017–2019) in two regions of Northern Algeria, we observed an overall prevalence of 6.5% of tuberculosis (TB) among slaughtered cattle, which is higher than previous Algerian data yet comparable to neighboring countries. A total of 296 Mycobacterium tuberculosis complex (MTBC) isolates were genotyped by spoligotyping: 181 from tissues with TB-like lesions collected from 181 cattle carcasses and 115 from TB patients. In human isolates, we identified 107 M. tuberculosis, seven M. bovis and one “M. pinnipedii-like”, while for bovine samples, 174 isolates were identified as M. bovis, three as M. caprae, three as “M. pinnipedii-like” and one as “M. microti-like”. The majority of isolates (89.2%) belonged to 72 different known Shared International Types (SIT) or M. bovis spoligotypes (SB), while we also identified seven new SB profiles (SB2695 to SB2701). Twenty-eight of the SB profiles were new to Algeria. Our data suggest zoonotic transmission in Sétif, where significantly more TB was observed among cattle (20%) compared to the slaughterhouses from the three other regions (5.4%–7.3%) (p < 0.0001), with the isolation of the same M. bovis genotypes from TB patients. The present study showed a high genetic diversity of MTBC isolated from human and cattle in Northern Algeria. Even though relatively small in terms of numbers, our data suggest the zoonotic transmission of TB from cattle to humans, suggesting the need for stronger eradication strategies for bovine TB.  相似文献   
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Sirtuins, NAD-dependent protein deacetylases, play important roles in cellular functions such as metabolism and differentiation. Whether sirtuins function in tumorigenesis is still controversial, but sirtuins are aberrantly expressed in tumors, which may keep cancerous cells undifferentiated. Therefore, we investigated whether the inhibition of sirtuin family proteins induces cellular differentiation in leukemic cells. The sirtuin inhibitors tenovin-6 and BML-266 induce granulocytic differentiation in the acute promyelocytic leukemia (APL) cell line NB4. This differentiation is likely caused by an inhibition of SIRT2 deacetylase activity, judging from the accumulation of acetylated α-tubulin, a major SIRT2 substrate. Unlike the clinically used differentiation inducer all-trans retinoic acid, tenovin-6 shows limited effects on promyelocytic leukemia–retinoic acid receptor α (PML-RAR-α) stability and promyelocytic leukemia nuclear body formation in NB4 cells, suggesting that tenovin-6 does not directly target PML-RAR-α activity. In agreement with this, tenovin-6 induces cellular differentiation in the non-APL cell line HL-60, where PML-RAR-α does not exist. Knocking down SIRT2 by shRNA induces granulocytic differentiation in NB4 cells, which demonstrates that the inhibition of SIRT2 activity is sufficient to induce cell differentiation in NB4 cells. The overexpression of SIRT2 in NB4 cells decreases the level of granulocytic differentiation induced by tenovin-6, which indicates that tenovin-6 induces granulocytic differentiation by inhibiting SIRT2 activity. Taken together, our data suggest that targeting SIRT2 is a viable strategy to induce leukemic cell differentiation.  相似文献   
9.
Small‐scale Jatropha cultivation and biodiesel production have the potential of contributing to local development, energy security, and greenhouse gas (GHG) mitigation. In recent years however, the GHG mitigation potential of biofuel crops is heavily disputed due to the occurrence of a carbon debt, caused by CO2 emissions from biomass and soil after land‐use change (LUC). Most published carbon footprint studies of Jatropha report modeled results based on a very limited database. In particular, little empirical data exist on the effects of Jatropha on biomass and soil C stocks. In this study, we used field data to quantify these C pools in three land uses in Mali, that is, Jatropha plantations, annual cropland, and fallow land, to estimate both the Jatropha C debt and its C sequestration potential. Four‐year‐old Jatropha plantations hold on average 2.3 Mg C ha?1 in their above‐ and belowground woody biomass, which is considerably lower compared to results from other regions. This can be explained by the adverse growing conditions and poor local management. No significant soil organic carbon (SOC) sequestration could be demonstrated after 4 years of cultivation. While the conversion of cropland to Jatropha does not entail significant C losses, the replacement of fallow land results in an average C debt of 34.7 Mg C ha?1, mainly caused by biomass removal (73%). Retaining native savannah woodland trees on the field during LUC and improved crop management focusing on SOC conservation can play an important role in reducing Jatropha's C debt. Although planting Jatropha on degraded, carbon‐poor cropland results in a limited C debt, the low biomass production, and seed yield attained on these lands reduce Jatropha's potential to sequester C and replace fossil fuels. Therefore, future research should mainly focus on increasing Jatropha's crop productivity in these degraded lands.  相似文献   
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