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11.
M. C. Manjabacas E. Valero M. García-Moreno C. Garrido R. Varón 《Bulletin of mathematical biology》1996,58(1):19-41
A global kinetic analysis of a model consisting of an autocatalytic zymogen-activation process, in which an irreversible inhibitor
competes with the zymogen for the active site of the proteinase, and a monitoring coupled reaction, in which the enzyme acts
upon one of its substrates, is presented. This analysis is based on the progress curves of any of the two products released
in the monitoring reaction. The general solution is applied to an important particular case in which rapid equilibrium conditions
prevail. Finally, we suggest a procedure to predict whether the inhibition or activation route dominates in the steady state
of the system. These results generalize our previous analysis of simpler mechanisms. 相似文献
12.
Physiological ecology of a metalimnetic Cryptomonas population: relationships to light, sulfide and nutrients 总被引:1,自引:0,他引:1
Gasol Josep M.; Garcia-Cantizano Josefina; Massana Ramon; Guerrero Ricardo; Pedros-Alio Carlos 《Journal of plankton research》1993,15(3):255-275
The possible mechanisms by which Cryptomonas phaseolus maintainsa large metalimnetic population during stratification were studiedin Lake Cisó. The population was shown to always remainat the oxygen-sulfide interface despite the fact that sometimesthe amount of light reaching was <1% of incident light. Thismeant that the amount of light reaching the peak was sometimesmuch lower than the optimum light intensity for photosynthesisof the population, which was 相似文献
13.
Low Selenium Diet Affects Monoamine Turnover Differentially in Substantia Nigra and Striatum 总被引:2,自引:1,他引:1
Abstract: Turnover of dopamine, noradrenaline. serotonin, and their metabolites has been measured in striatum and substantia nigra of adult female rats that were fed control or selenium-deficient diets for 15 days. In addition, the glutathione peroxidase activity has been studied. The most striking result was the increase of dopamine turnover (63%) and 3- methoxytyramine turnover (55%) in substantia nigra between control and experimental animals. On the other hand, no changes were found in the turnover rate of dopamine and its metabolites in the striatum. Likewise, no changes were found in noradrenaline turnover in substantia nigra. In the striatum, there was a significant increase of serotonin turnover versus no change for 5-hydroxy-3-indoleacetic acid. However, in the substantia nigra, serotonin turnover did not show significant changes, whereas 5-hydroxy-3-indoleacetic acid turnover decreased. At the same time, glutathione peroxidase activity significantly decreased in both structures after selenium-deficient diets. These results suggest that a selenium-deficient diet for a short period of time decreases brain protection. principally in the substantia nigra, against oxidative damage. 相似文献
14.
Roger S. McIntyre Mohammad Alsuwaidan Bernhard T. Baune Michael Berk Koen Demyttenaere Joseph F. Goldberg Philip Gorwood Roger Ho Siegfried Kasper Sidney H. Kennedy Josefina Ly-Uson Rodrigo B. Mansur R. Hamish McAllister-Williams James W. Murrough Charles B. Nemeroff Andrew A. Nierenberg Joshua D. Rosenblat Gerard Sanacora Alan F. Schatzberg Richard Shelton Stephen M. Stahl Madhukar H. Trivedi Eduard Vieta Maj Vinberg Nolan Williams Allan H. Young Mario Maj 《World psychiatry》2023,22(3):394-412
Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population. 相似文献
15.
Congenital syphilis has been diagnosed very seldom in ancient populations. The case that we examined comes from San Jeronimo's Church (17th and 18th centuries AD; Mexico City). Coffin 43 contained an incomplete skeleton of an approximately 2-year-old infant. The pathological lesions of this skeleton include bilateral osteochondritis, diaphyseal osteomyelitis, and osteitis and/or periostitis on the long bones. The radiographic appearance depicts symmetrical osteomyelitic foci, particularly at the proximal extremity of both tibiae (Wimberger's sign). The skull exhibits hydroceph-aly and periosteal changes on the vault, and the unerupted upper incisors evince dental hypoplasia and other pathological alterations reminiscent of Hutchinson's incisors. All these features strongly suggest a case of early Congenital syphilis. © 1995 Wiley-Liss, Inc. 相似文献
16.
Teresita A. Lisa Mónica N. Garrido Carlos E. Domenech 《Molecular and cellular biochemistry》1984,63(2):113-118
Summary Different compounds derived from choline, and obtained by demethylation or by oxidation of the primary alcohol group with subsequent N-demethylation, were tested as inducer agents of acid phosphatase and cholinesterase in Ps. aeruginosa. It was found that betaine and dimethylglycine were the most effective inducers of both enzyme activities. These metabolites including choline itself, were not inducers of acid phosphatase and cholinesterase in other Gram-negative bacteria such as: Escherichia coli, Salmonella typhimurium, Shigella flexneri, Enterobacter liquefacciens and Proteus mirabilis. The acid phosphatase activities found in these bacteria were not inhibited in vitro by choline, betaine and phosphorylcholine. From these results it may be concluded that the acid phosphatase activity from Ps. aeruginosa is different from the same activity observed in the other bacteria. In addition, it is also shown that Ps. aeruginosa acid phosphatase and cholinesterase were inhibited by a number of compounds containing a positively charged amino group, with methyl or ethyl groups bound to it. These results seem to confirm that Ps. aeruginosa acid phosphatase and cholinesterase may contain a similar anionic site. 相似文献
17.
Philip Coffino Henry R. Bourne Paul A. Insel Kenneth L. Melmon Gary Johnson Josefina Vigne 《In vitro cellular & developmental biology. Plant》1978,14(1):140-145
Summary S49 mouse lymphoma cell mutants, each with a specific defect in its ability to generate or respond to cyclic AMP, have been
isolated. Analysis of the properties of these cells has begun to provide information on complex and significant biologic problems
related to the cyclic AMP system.
Presented in the Opening Symposium on Nutritional Factors and Differentiation at the 28th Annual Meeting of the Tissue Culture
Association, New Orleans, Louisiana, June 6–9, 1977.
The work was supported in part by National Science Foundation Grant BMS 75-06764 and National Institutes of Health Grants
GM 16496 and GM 00001. P.C. is the recipient of National Institutes of Health Research Career Development Award GM 00308.
P. A. I. is an Established Investigator of the American Heart Association. 相似文献
18.
Josefina Martin-Barrientos Armando J. Parodi 《Molecular and cellular biochemistry》1977,16(2-3):111-117
Summary Human erythrocyte membranes contain the enzymes responsible for the synthesis of dolichol-P-glucose, dolichol-P-mannose, dolichol-PP-N-acetylglucosamine, dolichol-PP-NN diacetylchitobiose and of dolichol-PP-oligosaccharides containing NN diacetylchitobiose and mannose or the same sugar residues plus glucose. The transfer of the oligosaccharide moieties from the dolichol-PP-oligosaccharides to endogenous proteins could not be detected. These enzymes appeared to be integral membrane proteins.Abbreviation Dol
dolichol
Dedicated to ProfessorLuis f. Leloir on the occasion of his 70th birthday. 相似文献
19.
20.
V Faúndez R Krauss L Holuigue J Garrido A González 《The Journal of biological chemistry》1992,267(28):20363-20370
Functional relationships between epidermal growth factor (EGF) and neural tissues have of late attracted increasing interest. However, in spite of reported EGF effects on neurons, the expression of the EGF receptor (EGF-R) has not yet been unambiguously demonstrated in these cells. This 170-kDa protein bears an intracellular tyrosine kinase domain in which activity is ligand-dependent. We give definitive evidence here for its presence in neonatal and adult rat neurons showing also, for the first time, its binding and functional tyrosine kinase activities in the synaptic region. Immunohistochemistry using a polyclonal antibody prepared against the receptor purified from rat liver showed positive staining localized exclusively to neurons without regionalization to any particular brain zone. Binding studies made in Percoll-obtained synaptosomes revealed specific high affinity 125I-EGF binding sites (Kd, 1.42 x 10(-10) +/- 0.58 M) accounting for 17% of total binding and a great majority of low affinity (Kd, 2.55 x 10(-9) +/- 0.35 M) binding sites. Higher binding capacity was found in synaptosomal fractions obtained from newborn rats. The identity of the synaptosomal EGF binding activity with the 170-kDA EGF-R protein was demonstrated by cross-linking experiments. Furthermore, EGF-Affi-Prep affinity chromatography adsorbs a 170-kDa protein with EGF-R immunoreactivity from whole homogenates of adult rat brain. Phosphorylation assays made in freeze-thawed or intact synaptosomes showed EGF-induced tyrosine phosphorylation in the range of 170-, 126-150-, 124-, 113-, 98-, and 70-kDa proteins including the EGF-R. Thus, the EGF-R/EGF regulatory system could have a role in synaptic function that remains to be explored. 相似文献