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Results for “Indirect transfer”

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At least 73 records · Page 4Linked to original sources

PubMed2006

Does bradycardia or hypertension enhance gas transfer in rainbow trout (Oncorhynchus mykiss)?

Experiments were conducted to test the hypothesis that branchial gas transfer is enhanced in rainbow trout during hypoxia or hypercarbia by bradycardia and systemic vasoconstriction. Gas transfer was indirectly assessed by continuous monitoring of arterial blood gases, PaO2 and PaCO2. Cardiac frequency was maximally decreased by 34.9+/-4.3 and 8.6+/-3.2 bpm in hypoxic and hypercarbic fish, respectively. Pre-treating fish with atropine (1micromol kg(-1)) attenuated or abolished the bradycardia during hypoxia and hypercarbia, respectively. However, there were no significant differences in the arterial blood gases between the control and atropinized fish. Dorsal aortic blood pressure was increased maximally by 11.3+/-2.8 and 17.7+/-2.0mm Hg in the hypoxic and hypercarbic fish. Pre-treatment of fish with prazosin (2.4micromol kg(-1)) prevented these increases in blood pressure. Blood gases were unaltered by prazosin treatment in the hypercarbic fish. However, in the hypoxic fish, gas transfer appeared to be impaired by prazosin on the basis of lowered PaO2 (by approximately 35 mm Hg compared to control fish) and increased PaCO2 (by approximately 0.3mm Hg). Because the normal hyperventilatory response to hypoxia was prevented by prazosin, it is possible that the impairment of gas transfer was related to inadequate ventilation rather than to any differences in the pressor response. The present results provide no evidence that gas transfer in rainbow trout is enhanced by bradycardia nor do they reveal any obvious benefit associated with the increases in blood pressure that accompany hypoxia and hypercarbia.

Adrenergic alpha-Antagonists↗

PubMed1980

Regulation of nitrogen utilization of hisT mutants of Salmonella typhimurium.

Mutations in the hisT gene of Salmonella typhimurium alter pseudouridine synthetase I, the enzyme that modifies two uridines in the anticodon loop of numerous transfer ribonucleic acid species. We have examined two strains carrying different hisT mutations for their ability to grow on a variety of nitrogen sources. The hisT mutants grew more rapidly than did hisT+ strains with either arginine or proline as the nitrogen source and glucose as the carbon source. The hisT mutations were transduced into new strains to show that these growth properties were due to the hisT mutations. The hisT mutations did not influence the growth of mutants having altered glutamine synthetase regulation. Assays of the three primary ammonia-assimilatory enzymes, glutamate dehydrogenase, glutamine synthetase, and glutamate synthase, showed that glutamate synthase activities were lower in hisT mutants than in isogenic hisT+ controls; however, the glutamate dehydrogenase activity was about threefold higher in the hisT strains grown in glucose-arginine medium. The results suggest that the controls for enzyme synthesis for nitrogen utilization respond either directly or indirectly to transfer ribonucleic acid species affected by the hisT mutation.

Glutamate Dehydrogenase↗

PubMed2005

Allene and pentatetraene cations as models for intramolecular charge transfer: vibronic coupling Hamiltonian and conical intersections.

We consider the vibronic coupling effects involving cationic states with degenerate components that can be represented as charge localized at either end of the short cumulene molecules allene and pentatetraene. Our aim is to simulate dynamically the charge transfer process when one component is artificially depopulated. We model the Jahn-Teller vibronic interaction within these states as well as their pseudo-Jahn-Teller coupling with some neighboring states. For the manifold of these states, we have calculated cross sections of the ab initio adiabatic potential energy surfaces along all nuclear degrees of freedom, including points at large distances from the equilibrium to increase the physical significance of our model. Ab initio calculations for the cationic states of allene and pentatetraene were based on the fourth-order Møller-Plesset method and the outer valence Green's function method. In some cases we had to go beyond this method and use the more involved third-order algebraic diagrammatic construction method to include intersections with satellite states. The parameters for a five-state, all-mode diabatic vibronic coupling model Hamiltonian were least-square fitted to these potentials. The coupling parameters for the diabatic model Hamiltonian are such that, in comparison to allene, an enhanced preference for indirect charge transfer is predicted for pentatetraene.

Journal Article↗

PubMed1993

Rat pancreatic islet pretreatment with anti-MHC class II monoclonal antibodies and culture: in vitro MLIC test response does not predict islet allograft survival.

Antigen presenting cells (APC) expressing MHC class II antigens have been attributed with stimulatory capacity for initiating islet allograft rejection (direct pathway). Therefore, we evaluated the effect of pretreating isolated islets with different monoclonal antibodies against MHC class II antigens and complement, with and without culture at 22 degrees C or 37 degrees C, on MHC class II antigen expression, on the allogeneic proliferative response in the mixed lymphocyte islet culture (MLIC) and on islet allograft survival in adult rats. Experiments were performed in two different strain combinations incompatible for MHC class II antigens and either incompatible or compatible for MHC class I antigens, in order to elucidate further the impact of class I antigens on islet allograft rejection. In terms of class II antigen suppression, pretreatment with anti-MHC class II antibodies together with complement and a 5-day (37 degrees C) culture period proved most effective. After this procedure 92.7% of the islets of LEW rats and 91.1% of the islets of LEW.1WR2 rats were negative for MHC class II antigens, as demonstrated by indirect immunofluorescence. Transfer of successfully pretreated islets to a MLIC in vitro test system provoked a significantly reduced allogeneic T-cell proliferative response in the case of additional MHC class I disparity (ratio 1.3 vs 4.7) and a response as low as that of a syngeneic setting when stimulator islets and allogeneic responder lymphocytes shared MHC class I antigens (ratio 1.0 vs 1.6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2004

Correction of spin diffusion during iterative automated NOE assignment.

Indirect magnetization transfer increases the observed nuclear Overhauser enhancement (NOE) between two protons in many cases, leading to an underestimation of target distances. Wider distance bounds are necessary to account for this error. However, this leads to a loss of information and may reduce the quality of the structures generated from the inter-proton distances. Although several methods for spin diffusion correction have been published, they are often not employed to derive distance restraints. This prompted us to write a user-friendly and CPU-efficient method to correct for spin diffusion that is fully integrated in our program ambiguous restraints for iterative assignment (ARIA). ARIA thus allows automated iterative NOE assignment and structure calculation with spin diffusion corrected distances. The method relies on numerical integration of the coupled differential equations which govern relaxation by matrix squaring and sparse matrix techniques. We derive a correction factor for the distance restraints from calculated NOE volumes and inter-proton distances. To evaluate the impact of our spin diffusion correction, we tested the new calibration process extensively with data from the Pleckstrin homology (PH) domain of Mus musculus beta-spectrin. By comparing structures refined with and without spin diffusion correction, we show that spin diffusion corrected distance restraints give rise to structures of higher quality (notably fewer NOE violations and a more regular Ramachandran map). Furthermore, spin diffusion correction permits the use of tighter error bounds which improves the distinction between signal and noise in an automated NOE assignment scheme.

Algorithms↗

PubMed1989

A comparison of the usefulness of SpermMar and immunobead tests for the detection of antisperm antibodies.

We compared two testing protocols designed to detect immunoglobulin (Ig) G antibodies on sperm surfaces: (1) SpermMar (Ortho, Raritan, NJ) and (2) Immunobead Testing (Biorad, Richmond, CA). The standard SpermMar (SPMAR) protocol (direct test of unwashed semen) was performed with 47 ejaculates and found to be more sensitive than Immunobead Testing (IBT) on washed sperm, detecting five samples with greater than or equal to 30% bead binding, all of which by IBT had less than 20% bead binding. In contrast, when SPMAR was performed on washed sperm or with an indirect antibody transfer from serum or seminal plasma, SPMAR results gave mostly low values for bead binding in comparison with IBT. Our data suggest that SPMAR be used only in direct assays employing unwashed ejaculates, that it can be easily incorporated into routine semen analysis as a screening test, and that positive results should be confirmed by IBT (IgG and IgA).

Agglutination Tests↗

PubMed2001

Cooperative action of antioxidant defense systems in Drosophila.

Molecular oxygen is key to aerobic life but is also converted into cytotoxic byproducts referred to as reactive oxygen species (ROS). Intracellular defense systems that protect cells from ROS-induced damage include glutathione reductase (GR), thioredoxin reductase (TrxR), superoxide dismutase (Sod), and catalase (Cat). Sod and Cat constitute an evolutionary conserved ROS defense system against superoxide; Sod converts superoxide anions to H(2)O(2), and Cat prevents free hydroxyl radical formation by breaking down H(2)O(2) into oxygen and water. As a consequence, they are important effectors in the life span determination of the fly Drosophila. ROS defense by TrxR and GR is more indirect. They transfer reducing equivalents from NADPH to thioredoxin (Trx) and glutathione disulfide (GSSG), respectively, resulting in Trx(SH)(2) and glutathione (GSH), which act as effective intracellular antioxidants. TrxR and GR were found to be molecularly conserved. However, the single GR homolog of Drosophila specifies TrxR activity, which compensates for the absence of a true GR system for recycling GSH. We show that TrxR null mutations reduce the capacity to adequately protect cells from cytotoxic damage, resulting in larval death, whereas mutations causing reduced TrxR activity affect pupal eclosion and cause a severe reduction of the adult life span. We also provide genetic evidence for a functional interaction between TrxR, Sod1, and Cat, indicating that the burden of ROS metabolism in Drosophila is shared by the two defense systems.

Animals↗

PubMed2004

Electrochemical oxidation as a final treatment of synthetic tannery wastewater.

Vegetable tannery wastewaters contain high concentrations of organics and other chemicals that inhibit the activity of microorganisms during biological oxidations, so biorefractory organics that are not removed by biological treatment must be eliminated by a tertiary or advanced wastewater treatment. In this paper, the applicability of electrochemical oxidation as a tertiary treatment of a vegetable tannery wastewater was investigated by performing galvanostatic electrolysis using lead dioxide (Ti/PbO2) and mixed titanium and ruthenium oxide (Ti/TiRuO2) as anodes under different experimental conditions. The experimental results showed that both the electrodes performed complete mineralization of the wastewater. In particular, the oxidation took place on the PbO2 anode by direct electron transfer and indirect oxidation mediated by active chlorine, while it occurred on the Ti/TiRuO2 anode only by indirect oxidation. Furthermore, the Ti/PbO2 gave a somewhat higher oxidation rate than that observed for the Ti/TiRuO2 anode. Although the Ti/TiRuO2 required almost the same energy consumption for complete COD removal, it was more stable and did not release toxic ions, so it was the best candidate for industrial applications. With the Ti/TiRuO2 anode, the rate of tannery wastewater oxidation increased with the current density, pH, and temperature of the solution. These results strongly indicate that electrochemical methods can be applied effectively as a final treatment of vegetable tannery wastewater allowing the complete removal of COD, tannin, and ammonium and decolorization.

Electrodes↗

PubMed2005

Control of photoinduced energy- and electron-transfer steps in zinc porphyrin-oligothiophene-fullerene linked triads with solvent polarity.

The dramatic changes of the lifetimes of the charge-separated (CS) states were confirmed in zinc porphyrin (ZnP)-oligothiophene (nT)-fullerene (C(60)) linked triads (ZnP-nT-C(60)) with the solvent polarity. After the selective excitation of the ZnP moiety of ZnP-nT-C(60), an energy transfer took place from the (1)ZnP moiety to the C(60) moiety, generating ZnP-nT-(1)C(60). In polar solvents, the CS process also took place directly via the (1)ZnP moiety, generating ZnP(*+)-nT-C(60)(*-), as well as the energy transfer to the C(60) moiety. After this energy transfer, an indirect CS process took place from the (1)C(60) moiety. In the less polar solvent anisole, the radical cation (hole) of ZnP(*+)-nT-C(60)(*-) shifted to the nT moiety; thus, the nT moiety behaves as a cation trapper, and the rates of the hole shift were evaluated to be in the order of 10(8) s(-1); then, the final CS states ZnP-nT(*+)-C(60)(*-) were lasting for 6-7 mus. In the medium polar solvent o-dichlorobenzene (o-DCB), ZnP-nT(*+)-C(60)(*-) and ZnP(*+)-nT-C(60)(*-) were present as an equilibrium, because both states have almost the same thermodynamic stability. This equilibrium resulted in quite long lifetimes of the CS states (450-910 mus) in o-DCB. In the more polar benzonitrile, the generation of ZnP-nT(*+)-C(60)(*-) was confirmed with apparent short lifetimes (0.6-0.8 mus), which can be explained by the fast hole shift to more stable ZnP(*+)-nT-C(60)(*-) followed by the faster charge recombination. It was revealed that the relation between the energy levels of two CS states, which strongly depend on the solvent polarity, causes dramatic changes of the lifetimes of the CS states in ZnP-nT-C(60); that is, the most appropriate solvents for the long-lived CS state are intermediately polar solvents such as o-DCB. Compared with our previous data for H(2)P-nT-C(60), in which H(2)P is free-base porphyrin, the lifetimes of the CS states of ZnP-nT-C(60) are approximately 30 times longer than those in o-DCB.

Journal Article↗

PubMed1978

Bacille Calmette-Guérin infection in the mouse. Regulation of macrophage plasminogen activator by T lymphocytes and specific antigen.

High levels of plasminogen activator (PA) were induced in mouse peritoneal macrophages by infection with BCG, 2-6 X 10(7) viable organisms intravenously, followed 3-4 wk later by intraperitoneal challenge with purified protein derivative (PPD) 2 days before harvest. Macrophages obtained from infected animal without boosting showed little fibrinolytic activity, but challenge of Bacille-Calmette-Guèrin (BCG)-primed peritoneal cells with PPD in culture also enhanced macrophage PA 4- to 10-fold. Stimulation of macrophage PA by PPD depended on specifically sensitized thymus-derived (T) lymphocytes because it was abolished by pretreatment of BCG-primed peritoneal cells with anti-thy 1.2 antiserum and complement. A direct assay was developed in which nylon wool separated sensitized lymphocytes and PPD induced PA in macrophages from uninfected animals under defined conditions on 125I-fibrin. Enhanced macrophage fibrinolysis was proportional to concentration of PPD and the number of sensitized lymphocytes transferred. An indirect two-stage assay was also used to show that BCG-sensitized peritoneal cells released a soluble inducer of macrophage PA into the culture medium, after challenge with PPD. Induction of macrophage PA by PPD challenge in vitro made it possible to study the generation and activity of sensitized peritoneal lymphocytes at different stages of infection. Our results show that nonadherent peritoneal cells of BCG-infected mice provide a rich source of specifically sensitized lymphocytes and that macrophage activation is limited by continued availability of antigen, as well as sensitized lymphocytes. Induction of macrophage PA provides a sensitive, versatile, and rapid in vitro assay to study the role of lymphocytes and specific antigen in macrophage activation by BCG.

Animals↗

PubMed2004

Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme.

Heme oxygenase (HO) catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equivalents. In photosynthetic organisms, HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins, which are involved in the signal transduction for light responses and light harvesting for photosynthesis, respectively. We have determined the first crystal structure of a HO-1 from a photosynthetic organism, Synechocystis sp. PCC 6803 (Syn HO-1), in complex with heme at 2.5 A resolution. Heme-Syn HO-1 shares a common folding with other heme-HOs. Although the heme pocket of heme-Syn HO-1 is, for the most part, similar to that of mammalian HO-1, they differ in such features as the flexibility of the distal helix and hydrophobicity. In addition, 2-propanol derived from the crystallization solution occupied the hydrophobic cavity, which is proposed to be a CO trapping site in rat HO-1 that suppresses product inhibition. Although Syn HO-1 and mammalian HO-1 are similar in overall structure and amino acid sequence (57% similarity vs. human HO-1), their molecular surfaces differ in charge distribution. The surfaces of the heme binding sides are both positively charged, but this patch of Syn HO-1 is narrow compared to that of mammalian HO-1. This feature is suited to the selective binding of ferredoxin, the physiological redox partner of Syn HO-1; the molecular size of ferredoxin is approximately 10 kDa whereas the size of NADPH-cytochrome P450 reductase, a reducing partner of mammalian HO-1, is approximately 77 kDa. A docking model of heme-Syn HO-1 and ferredoxin suggests indirect electron transfer from an iron-sulfur cluster in ferredoxin to the heme iron of heme-Syn HO-1.

Amino Acid Sequence↗

PubMed1994

Improved contrast of enhancing brain lesions on postgadolinium, T1-weighted spin-echo images with use of magnetization transfer.

PURPOSE: To prove that the contrast of enhancing brain lesions on post-gadolinium T1-weighted spin-echo (SE) images can be statistically significantly improved with magnetization-transfer (MT) indirect saturation. MATERIALS AND METHODS: The contrast-to-noise ratios (C/Ns) of 201 enhancing brain lesions in 110 patients were compared on conventional and MT T1-weighted SE images obtained at 1.5 T after injection of 0.05-0.10 mmol/kg gadopentetate dimeglumine or gadodiamide. RESULTS: The MT T1-weighted SE images showed a 37% reduction in signal intensity of background white matter and thereby provided a 108% improvement in the C/N of enhancing brain lesions over the conventional T1-weighted SE images (P < .001). CONCLUSION: The C/Ns obtained with single-dose gadolinium and the MT T1-weighted SE technique were twice those obtained with the conventional technique and are at least equivalent to reported values obtained with triple-dose gadolinium and conventional T1-weighted SE images.

Brain↗

PubMed2005

A novel Geobacteraceae-specific outer membrane protein J (OmpJ) is essential for electron transport to Fe(III) and Mn(IV) oxides in Geobacter sulfurreducens.

BACKGROUND: Metal reduction is thought to take place at or near the bacterial outer membrane and, thus, outer membrane proteins in the model dissimilatory metal-reducing organism Geobacter sulfurreducens are of interest to understand the mechanisms of Fe(III) reduction in the Geobacter species that are the predominant Fe(III) reducers in many environments. Previous studies have implicated periplasmic and outer membrane cytochromes in electron transfer to metals. Here we show that the most abundant outer membrane protein of G. sulfurreducens, OmpJ, is not a cytochrome yet it is required for metal respiration. RESULTS: When outer membrane proteins of G. sulfurreducens were separated via SDS-PAGE, one protein, designated OmpJ (outer membrane protein J), was particularly abundant. The encoding gene, which was identified from mass spectrometry analysis of peptide fragments, is present in other Geobacteraceae, but not in organisms outside this family. The predicted localization and structure of the OmpJ protein suggested that it was a porin. Deletion of the ompJ gene in G. sulfurreducens produced a strain that grew as well as the wild-type strain with fumarate as the electron acceptor but could not grow with metals, such as soluble or insoluble Fe(III) and insoluble Mn(IV) oxide, as the electron acceptor. The heme c content in the mutant strain was ca. 50% of the wild-type and there was a widespread loss of multiple cytochromes from soluble and membrane fractions. Transmission electron microscopy analyses of mutant cells revealed an unusually enlarged periplasm, which is likely to trigger extracytoplasmic stress response mechanisms leading to the degradation of periplasmic and/or outer membrane proteins, such as cytochromes, required for metal reduction. Thus, the loss of the capacity for extracellular electron transport in the mutant could be due to the missing c-type cytochromes, or some more direct, but as yet unknown, role of OmpJ in metal reduction. CONCLUSION: OmpJ is a putative porin found in the outer membrane of the model metal reducer G. sulfurreducens that is required for respiration of extracellular electron acceptors such as soluble and insoluble metals. The effect of OmpJ in extracellular electron transfer is indirect, as OmpJ is required to keep the integrity of the periplasmic space necessary for proper folding and functioning of periplasmic and outer membrane electron transport components. The exclusive presence of ompJ in members of the Geobacteraceae family as well as its role in metal reduction suggest that the ompJ sequence may be useful in tracking the growth or activity of Geobacteraceae in sedimentary environments.

Amino Acid Sequence↗

PubMed2002

Functional expression of NF1 tumor suppressor protein: association with keratin intermediate filaments during the early development of human epidermis.

BACKGROUND: NF1 refers to type 1 neurofibromatosis syndrome, which has been linked with mutations of the large NF1 gene. NF1 tumor suppressor protein, neurofibromin, has been shown to regulate ras: the NF1 protein contains a GTPase activating protein (GAP) related domain which functions as p21rasGAP. Our studies have previously demonstrated that the NF1 protein forms a high affinity association with cytokeratin 14 during the formation of desmosomes and hemidesmosomes in cultured keratinocytes. METHODS: The expression of NF1 protein was studied in developing human epidermis using western transfer analysis, indirect immunofluorescence, confocal laser scanning microscopy, immunoelectron microscopy, and in situ hybridization. RESULTS: The expression of NF1 protein was noted to be highly elevated in the periderm at 8 weeks estimated gestational age (EGA) and in the basal cells at 8-14 weeks EGA. During this period, NF1 protein was associated with cytokeratin filaments terminating to desmosomes and hemidesmosomes. NF1 protein did not display colocalization with alpha-tubulin or actin of the cytoskeleton, or with adherens junction proteins. CONCLUSIONS: These results depict an early fetal period when the NF1 tumor suppressor is abundantly expressed in epidermis and associated with cytokeratin filaments. This period is characterized by the initiation of differentiation of the basal cells, maturation of the basement membrane zone as well as accentuated formation of selected cellular junctions. NF1 tumor suppressor may function in the regulation of epidermal histogenesis via controlling the organization of the keratin cytoskeleton during the assembly of desmosomes and hemidesmosomes.

Adult↗

PubMed1998

Activation patterns and length changes in hindlimb muscles of the bullfrog Rana catesbeiana during jumping.

We measured the electromyographic (EMG) activity of seven hindlimb muscles during jumping in the bullfrog Rana catesbeiana. The semimembranosus, gracilis major, gluteus magnus, adductor magnus, cruralis and plantaris longus were consistently active approximately 20-40 ms before any perceptible movement, as indicated by simultaneous video recordings. Activity ended before full extension of the hindlimb and take-off. Activity in the semitendinosus was variable among the jumps recorded. Simultaneous measurements of EMG activity and length changes (via sonomicrometry) in the semimembranosus (SM) and gluteus magnus (GM) muscles indicated that the performance characteristics of these two muscles differed. The SM muscle (a hip extensor) shortens and is activated in a manner consistent with its producing power during a significant fraction of the take-off phase. It shortened by a mean of 26.2% of the resting length during the propulsive phase of the two longest jumps for each frog. The delay between the onset of EMG activity and the beginning of shortening averaged 24 ms, which was brief compared with that found for the GM. The total strain and mean shortening velocity of the SM increased with jumping distance. Contrary to our initial expectations, the GM muscle does not shorten as one would expect of a muscle involved in powering the jump throughout take-off. This muscle has an extensor action at the knee, but also has a flexor action at the hip. A long delay existed between the onset of EMG activity and the beginning of shortening (46-116 ms among the individuals tested). Shortening during take-off by the GM (a mean of 16.7% for all jumps) was much less than by the SM, and in many jumps most of this shortening occurred late in the take-off period. Although the GM cannot contribute directly to power output early in take-off, it may contribute to powering the jump indirectly by transferring energy from the hip extensors to the knee joint. We conclude that muscles previously assumed (on the basis of anatomical criteria) by ourselves and others to be powering the jump may show considerable diversity of function. We hypothesize that elastic energy storage is used to help power jumping, and therefore suggest that muscles in series with major tendinous elements should be targeted for further study.

Animals↗

PubMed1975

Polymyxin B reactions, IgE antibody, and T-cell deficiency. Immunochemical studies in a patient after bone marrow transplantation.

A patient with aplastic anemia was immunosuppressed with cyclophosphamide and transplanted with allogenic bone marrow. While lacking demonstrable T-cell activity posttransplantation, he developed a generalized macular erythematous eruption and fever, clinically attributed to intranasal polymyxin B. A specific IgE antibody, demonstrated by direct skin testing, Prausnitz-Kustner passive transfer, and indirect passive hemagglutination was temporally related to the reaction. Discontinuation of the drug led to prompt defervescence and resolution of the drug eruption.

Adolescent↗

PubMed2002

[Drugs and pregnancy].

The evidence of the transplacental transfer of most of the drugs administered to the mother has changed the old concept of the invulnerability of the fetus due to the placental barrier protection. The commonly used drugs act on the fetus by means of two different mechanisms: directly after the placental transfer, and indirectly influencing the utero-placental circulation and maternal homeostasis. Fetal effects can be several and they depend on the type of the drug, dosage, route of administration, gestational age in relation to the fetal ontogenesis, and on the amount of drug which reaches the fetus. For example, some drugs are redistributed in the maternal compartment; others remain in the fetal compartment by virtue of their chemical-physical characteristics and/or altered fetal homeostasis, i.e., fetal acidosis results in ionisation of the loco-regional anesthetics, which cannot leave the fetus, and therefore are entrapped in the fetal compartment. The complexity of the fetal-maternal pharmacology has implemented research on the animals, and epidemiologic and clinic studies. In spite of the research performed in the last years, the long-term perinatal effects are still to be clarified for many drugs administered to the mother.

Alcoholism↗

PubMed1982

Calcium binding domains of calmodulin. Sequence of fill as determined with terbium luminescence.

Terbium, a trivalent lanthanide, effectively substituted for Ca2+ in calmodulin as judged by several criteria: intrinsic fluorescence spectra, altered mobilities on polyacrylamide gel electrophoresis, formation of a stable complex with troponin I or calcineurin, and stimulation of phosphodiesterase. Calmodulin harbors four Ca2+ binding domains; domains I and II contain no tyrosine, whereas domains III and IV each have one tyrosine. The binding of Tb3+ to calmodulin was followed by the increase of Tb3+ fluorescence at 545 nm upon binding to calmodulin. This fluorescence was elicited either by exciting Tb3+ directly at 222 nm or by exciting the calmodulin tyrosine at 280 nm with resulting energy transfer from tyrosine to Tb3+. Fluorescence generated by direct excitation measures binding of Tb3+ to any of the Ca2+ binding domains, whereas energy transfer through indirect excitation is effective only when Tb3+ is within 5 A of tyrosine, indicating that Tb3+ necessarily occupies a Ca2+ binding domain that contains tyrosine. A judicious use of the direct and indirect excitation could reveal the sequence of fill of the binding domains. Our results suggest these domains are filled in the following sequence: 1) domain I or II; 2) domains III and IV; and 3) domain II or I that has not been filled initially.

Animals↗