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1.
Summary Bicarbonate-stimulated Mg2+ dependent ATPase activity was demonstrated both biochemically and cytochemically, in brush border membranes from rat, rabbit and guinea pig duodenum. There was no correlation between enzyme activity and basal HCO
3
-
secretion rates in the different species. The concentration of HCO
3
-
necessary for optimal stimulation of ATPase activity, degree of stimulation and total activity was higher in the rat than in other species. Activity was higher in rat duodenum than in the ileum. This is consistent with the proposed electrogenic HCO
3
-
secretion in the duodenum. Distribution of activities of alkaline phosphatase and HCO
3
-
-stimulated Mg2+-ATPase along the duodenal villus showed significant differences, suggesting that the two activities reflect, at least in part, distinct enzymes. 相似文献
2.
3.
M. Hamdi 《Bioprocess and biosystems engineering》1995,12(4):193-197
A convenient physical model for biomass involves consideration of individual cells as active centers dispersed through a continuous region in which transport takes place by molecular diffusion. This paper investigates for steady state conditions the variation of apparent kinetic constant (K
m
) of bacteria in relation to biofloc diameter with solid and/or liquid-phase diffusion. When the biochemical reactions are limited only by liquid-phase diffusion, theK
m
increases whenD increases. With solid-phase diffusion limitation only, theK
m
increases linearly with the diameterD of the floc. When both solid and liquid-phase diffusion limitations are considered, the apparentK
m
is affected by liquid-phase diffusion limitation with very smallD and by solid-phase diffusion limitation with higherD. The critical diameterD
c
can be assumed to be theD at which solid-phase diffusion limitation becomes more significant than liquid-phase diffusion limitation. 相似文献
4.
This paper describes an experimental investigation concerning the use of neural networks to achieve the non-linear control of a continuous stirred tank fermenter. The influent dilution rate and the substrate concentration have been selected as control variables. The backpropagation learning algorithm has been used for both off-line and on-line identification of the inverse model which provides the control action. Experimental results show the performance and the implementation simplicity of this control approach. 相似文献
5.
M A Hassan N J Miller I M Hamdi S A el-Adawi M al-Zaid M A al-Awqati 《Hormones et métabolisme》1991,23(2):85-87
Serum concentrations of sex hormone binding globulin, transcortin, thyroxine binding globulin, transthyretin together with retinol binding protein, ceruloplasmin, transferrin and albumin were measured sequentially in pregnant women in order to derive more definite suppositions relating to the prime function of hormone binding proteins. Thus, the fact that except for transthyretin all other specific hormone binding proteins exhibited appreciable but significantly variable increases would suggest: a) the apparent existence of more complex mechanisms regulating protein metabolism during pregnancy than hitherto postulated (i.e. the general notion of an integrated estrogen influence); b) a major and distinctive role for each of the hormone binding proteins is plausible since alterations in hormonal requirements by the fetus as pregnancy progresses can not be provided by the almost constant transplacental transfer rate of the "free" hormone moiety. 相似文献
6.
7.
Zouhour Ouali Imed Sbissi Soumaya Boudagga Azza Rhaiem Chadlia Hamdi Giuseppe Venturella 《Plant biosystems》2020,154(1):24-28
AbstractThe rare fungus Hericium erinaceus (Bull.) Pers. was collected from temperate forests in northwestern Tunisia and described for the first time in Africa. In this paper, we report data about the distribution, ecology, morphology and molecular identification of H. erinaceus. Collected data may help expand our knowledge on this critically endangered rare species worldwide. 相似文献
8.
Hamdi Ilhem Benmansour Bouchra Zouari-Tlig Sabiha Kamanli Seyit Ali Özak Argun Akif Boxshall Geoffrey Allan 《Systematic parasitology》2021,98(1):57-71
Systematic Parasitology - A new species of parasitic copepod, Caligus tunisiensis n. sp. (Caligidae), is described based on two female specimens collected from the gills of the painted comber,... 相似文献
9.
Ksontini Hamid Kachouri Faten El Abed Soumya Ibnsouda Koraichi Saad Meftah Hasna Latrache Hassan Hamdi Moktar 《Microbiology》2013,82(1):22-28
The initial microorganism adhesion on substrate is an important step for the biofilm formation. The surface properties of the stainless steel and B. cereus were characterized by the sessile drop technique. Moreover, the physicochemical properties of surface adhesion and the impact of bio adhesion to the stainless steel were determined at different time of contact (2, 4, 7, 9 and 24 h). The results showed that the strain was hydrophilic (Giwi = 3.37 mJ/m2), whereas the substratum has hydrophobic character (Giwi = ?57.6 mJ/m2). Stainless steel surface presents a weak electron-donor character (γ? = 4.1 mJ/m2) conversely to B. cereus that presents an important parameter (γ? = 31.6 mJ/m2). The bio adhesion was investigated at different time of contact. The data analysis after 2 h, confirmed the adhesion of B. cereus with an amount of 10 cfu/cm2 which increased to 1.2104 cfu/cm2 after 24 h. Interestingly, despite the difference of hydropohbicity, the interaction between B. cereus and substratum was favored by the thermodynamic aspect of adhesion (ΔGadhesion < 0). Interestingly, the study of the effect of B. cereus adhesion on the stainless steel has revealed that, the substratum becomes hydrophilic (θ° = 41.3, ΔGiwi = 39.6 mJ/m2) and highly electron donor (Γ? = 52.9 mJ/m2) after 2 h of bio adhesion. 相似文献
10.
Hadhemi Kaddour Yosra Hamdi David Vaudry Magalie Basille Laurence Desrues Jérôme Leprince Hélène Castel Hubert Vaudry Marie‐Christine Tonon Mohamed Amri Olfa Masmoudi‐Kouki 《Journal of neurochemistry》2013,125(4):620-633
Oxidative stress, induced by various neurodegenerative diseases, initiates a cascade of events leading to apoptosis, and thus plays a critical role in neuronal injury. In this study, we have investigated the potential neuroprotective effect of the octadecaneuropeptide (ODN) on 6‐hydroxydopamine (6‐OHDA)‐induced oxidative stress and apoptosis in cerebellar granule neurons (CGN). ODN, which is produced by astrocytes, is an endogenous ligand for both central‐type benzodiazepine receptors (CBR) and a metabotropic receptor. Incubation of neurons with subnanomolar concentrations of ODN (10?18 to 10?12 M) inhibited 6‐OHDA‐evoked cell death in a concentration‐dependent manner. The effect of ODN on neuronal survival was abrogated by the metabotropic receptor antagonist, cyclo1–8[DLeu5]OP, but not by a CBR antagonist. ODN stimulated polyphosphoinositide turnover and ERK phosphorylation in CGN. The protective effect of ODN against 6‐OHDA toxicity involved the phospholipase C/ERK MAPK transduction cascade. 6‐OHDA treatment induced an accumulation of reactive oxygen species, an increase of the expression of the pro‐apoptotic gene Bax, a drop of the mitochondrial membrane potential and a stimulation of caspase‐3 activity. Exposure of 6‐OHDA‐treated cells to ODN blocked all the deleterious effects of the toxin. Taken together, these data demonstrate for the first time that ODN is a neuroprotective agent that prevents 6‐OHDA‐induced oxidative stress and apoptotic cell death. 相似文献