In vivo electron paramagnetic resonance imaging of skin.
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Animals↗
Biomedical subjects
J Fuchs
Publications and source records attributed to J Fuchs.
Antioxidant inhibition of skin inflammation induced by reactive oxidants: evaluation of the redox couple dihydrolipoate/lipoate.
Reactive oxygen species play an important role in mediating skin inflammation, and antioxidants may provide protection. We investigated the anti-inflammatory activity of natural antioxidants, such as superoxide dismutase, catalase, trolox (a water-soluble tocopherol analog) and the redox couple dihydrolipoate/lipoate in skin. Furthermore we compared the anti-inflammatory potency of natural R and racemic dihydrolipoate, as well as R and S lipoate. Skin inflammation in hairless mice was induced by intradermal injection of the hydrogen peroxide producing enzyme glucose oxidase (GOD) or by topical application of the prooxidant drug anthralin. Intradermal injection of the antioxidants inhibited skin inflammation caused by GOD (catalase, dihydrolipoate) and anthralin (trolox, superoxide dismutase, dihydrolipoate). There was no statistically significant difference between the anti-inflammatory activity of the natural R and racemic dihydrolipoate. R or S lipoate did not inhibit skin inflammation when injected intradermally. In feeding experiments, however, R lipoate significantly inhibited GOD-mediated skin inflammation, while S lipoate was only marginally protective. We conclude that (1) several natural antioxidants such as catalase, superoxide dismutase and dihydrolipoate have anti-inflammatory properties in dermatitis induced by reactive oxidants, (2) lipoate (oxidized dihydrolipoate) has skin anti-inflammatory activity when administered orally and (3) naturally occurring R lipoate is a more potent anti-inflammatory agent than the non-physiological S lipoate.
Animals↗
Penetration of spin-labeled dihydrolipoate into the skin of hairless mice. Modification of epidermal and dermal polarity.
Electron paramagnetic resonance (EPR) imaging with the modulated field gradient technique is a novel method to investigate skin biophysical and biochemical properties employing specific nitroxide spin probes. Using this method, a distinct increase in polarity from epidermis towards lower dermis is observed with the spin label dit-butylnitroxide (DTBN). With proxylmaleimide a considerable increase in mobility is found, when epidermis is compared with dermal compartments. The effect of the natural antioxidant dihydrolipoate on skin membrane polarity was studied. Skin penetration of spin labeled dihydrolipoate was investigated by EPR imaging. The results indicate that dihydrolipoate also increases membrane polarity. The biophysical and biochemical changes in the epidermis and dermis as revealed by spatial imaging, provide indirect evidence for skin penetration of dihydrolipoate. This conclusion was supported by the finding that spin labeled derivatives of dihydrolipoate and lipoate were detected inside epidermis and dermis by EPR imaging. This study demonstrates the feasibility of EPR imaging to investigate pharmacodynamic and pharmacokinetic properties of spin labeled drugs in skin.
Animals↗
[Vitamins and skin].
Mucocutaneous changes occur in vitamin deficiency states and may be helpful in clinical diagnosis of the underlying disease. Substitution and therapy with vitamins can also cause skin problems, which may be of allergic of nonallergic origin. The skin and mucosal changes in pellagra and scurvy can be diagnostic; however, in other vitamin deficiencies, skin signs are rather unspecific. In most cases combined vitamin deficiencies occur that result in polymorphic and nonspecific mucocutaneous signs. Vitamin deficiencies are due to malnutrition, malabsorption or genetic defects. In industrialized countries alcoholism and gastrointestinal disorders are the main cause of vitamin deficiencies. Alcoholics or patients with malabsorption syndrome suffering from seborrheic dermatitis-like or ichthyosiform-like eruptions should be investigated for vitamin deficiency. Laboratory analysis of blood and urine vitamin levels can be misleading because of the poor correlation with tissue vitamin concentrations. Rapid clinical improvement following vitamin substitution frequently confirms the clinical diagnosis. In this overview we describe mucocutaneous signs of vitamin deficiencies. Excellent reviews of this topic are recommended for further reading [1-5].
Avitaminosis↗
Case study of the anemic patient: epoetin alfa--focus on inflammation.
Infection and inflammation are common problems in patients with end-stage renal disease. Both conditions can interfere with normal erythropoiesis and lead to a worsening of anemia and a suboptimal response to Epoetin alfa therapy. By understanding the pathophysiologic effects of infection and inflammation, assessing the patient's clinical status, and analyzing relevant laboratory values, nurses can intervene early and minimize the impact of these conditions on hematocrit.
Adult↗
Crevice-forming mutants in the rigid core of bovine pancreatic trypsin inhibitor: crystal structures of F22A, Y23A, N43G, and F45A.
Crystal structures of four mutants of bovine pancreatic trypsin inhibitor (F22A, Y23A, N43G, and F45A), engineered to alter their stability properties, have been determined. The mutated residues, which are highly conserved among Kunitz-type inhibitors, are located in the rigid core of the molecule. Replacement of the partially buried bulky residues of the wild-type protein with smaller residues resulted in crevices open to the exterior of the molecule. The overall three-dimensional structure of these mutants is very similar to that of the wild-type protein and only small rearrangements are observed among the atoms lining the crevices.
Animals↗
Crevice-forming mutants of bovine pancreatic trypsin inhibitor: stability changes and new hydrophobic surface.
Four mutants of bovine pancreatic trypsin inhibitor (BPTI) with replacements in the rigid core result in the creation of deep crevices on the surface of the protein. Other than crevices at the site of the mutation, few other differences are observed in the crystal structures of wild-type BPTI and the mutants F22A, Y23A, N43G, and F45A. These mutants are highly destabilized relative to wild type (WT). The differences between WT and mutants in the free energy change associated with cooperative folding/unfolding, delta delta G0 (WT-->mut), have been measured by calorimetry, and they are in good agreement with delta delta G0(WT-->mut) values from hydrogen exchange rates. For F22A the change in free energy difference is about 1.7 kcal/mol at 25 degrees C; for the other three mutants it is in the range of 5-7 kcal/mol at 25 degrees C. The experimental delta delta G0(WT-->mut) values of F22A, Y23A, and F45A are reasonably well accounted for as the sum of two terms: the difference in transfer free energy change, and a contribution from exposure to solvent of new surface (Eriksson, A.E., et al., 1992, Science 255, 178-183), if the recently corrected transfer free energies and surface hydrophobicities (De Young, L. & Dill, K., 1990, J. Phys. Chem. 94, 801-809; Sharp, K.A., et al., 1991a, Science 252, 106-109) are used and only nonpolar surface is taken into account. In N43G, three protein-protein hydrogen bonds are replaced by protein-water hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Localization of seed protein genes on flow-sorted field bean chromosomes.
Chromosomes from reconstructed field bean (Vicia faba L.) karyotypes were flow-sorted and the DNA was used for the physical localization of seed storage and nonstorage (USP) protein genes using PCR with sequence specific primers. The data were confirmed and refined by using DNA of microisolated chromosomes of other karyotypes as the target for PCR. The specificity of the PCR products was proved by restrictase digestion into fragments of predicted length or by reamplification using 'nested' primers. The genes are located within defined regions of chromosome I (USP = unknown seed protein genes), II (vicilin genes, legumin B3 genes), III (legumin B4 genes), IV (pseudogenes psi 1) and V (legumin A genes and pseudogenes psi 1). Except for the pseudogene derived from the sequence of legumin B4 gene, all members of each gene family are located in one chromosome region exclusively. This approach proved to be useful for localizing genes that cannot be mapped genetically (due to the lack of allelic variants) and might be applied to integrate physical and genetic maps.
Base Sequence↗
Nitroxide radical biostability in skin.
Nitroxide radicals are important chemical tools in dermatologic research (e.g., for studying biophysical properties of skin lipids and epidermal membranes with the method of electron paramagnetic resonance, EPR, spectroscopy). However, nitroxides may loose their paramagnetic properties in biological tissues, which could limit their usefulness in biomedical applications. We analyzed the biostability of various chemical types of nitroxide radicals in keratinocytes, epidermis homogenate, and intact skin. EPR signal loss of imidazoline, pyrrolidine, piperidine, and oxazolidine nitroxides is attributed to their reduction to the corresponding hydroxylamine. The rate of nitroxide reduction in skin varies considerably with nitroxide ring structure and substitution. The order of nitroxide stability in isolated human keratinocytes, mouse epidermis homogenate, and intact mouse and human skin is imidazoline > pyrrolidine > di-t-butylnitroxide (DTBN) > piperidine > oxazolidine. Cationic nitroxides are reduced much faster than neutral or anionic probes, presumably due to transmembrane electron shuttle or internalization. The results indicate that imidazoline- and pyrrolidine-type nitroxides should be used when high biostability of nitroxides is needed. Piperidine-type nitroxides are versatile probes for studying one-electron transfer reactions in skin.
Animals↗
Beneficial effect of amrinone on the size of acute regional ischemia in isolated rabbit hearts.
The effect of inotropes on myocardial ischemia is difficult to predict because they may influence the determinants of myocardial O2 demand and O2 supply differently. Several PDE-inhibitors have been reported to possess antiischemic properties related to their hemodynamic and O2-sparing effects. To assess whether PDE-inhibitors also possess direct cardioprotective properties, the effects of amrinone (2.5 x 10(-5) mol/L) in comparison to isoproterenol (5 x 10(-9) mol/L) and ouabain (1.5 x 10(-7) mol/L) were studied in isolated rabbit hearts perfused according to Langendorff at a constant pressure (70 cmH2O) and electrically driven at a constant pacing rate. Regional ischemia was induced by coronary artery ligation and quantified by epicardial NADH fluorescence. All substances significantly increased the actively developed left ventricular pressure to a similar extent (+20%) (P < 0.05). Coronary flow was significantly decreased by ouabain (-15%) and significantly increased by isoproterenol (+25%) and particularly by amrinone (+50%) (P < 0.05). Neither ouabain nor isoproterenol significantly changed the intensity or the distribution pattern of NADH fluorescence, whereas the size of the ischemic zone was significantly reduced by amrinone (-25%) (P < 0.05). The PDE-inhibitor amrinone was shown to possess a direct cardioprotective effect by improving myocardial perfusion and O2 supply in isolated rabbit hearts.
Amrinone↗
Fluctuations of carbohydrates in haemolymph of honeybee (Apis mellifica) after fasting, feeding and stress.
The haemolymph of honeybee contains trehalose, a non-reducing disaccharide, glucose and fructose. The aim of this work was to describe changes of haemolymph sugar induced by different physiological situations. Gas chromatography for the determination of carbohydrate concentrations in the haemolymph was introduced. The individual bee was anesthetized by CO2 and punctured at tergum III in order to gain 1 microliter haemolymph using a glass capilette. The main sugars in the haemolymph were determined as silylated derivatives by gas chromatography. Bees living under exactly standardized conditions in an artificial bee-house were observed after feeding and fasting. In addition saccharides were determined after "run-stress" along different distances.
Animals↗
Characterization of DNA adducts at the bay region of dibenz[a,h]anthracene formed in vitro.
Bay region diolepoxide-DNA adducts of dibenz[a,h]anthracene (DBA) formed in vitro were identified and their absolute stereochemistry was assigned. After activation of [5,12-14C]DBA with liver microsomes obtained from Aroclor 1254 treated male Sprague-Dawley rats in the presence of calf thymus DNA for 1 h, the amount of DNA adducts was found to be 9.9 +/- 2.4 pmol/mg DNA, calculated on the basis of the portion of radioactivity eluted from the HPLC reversed-phase column with a water/acetonitrile gradient. Bay region diolepoxide-DNA adducts represented 27.5% of radioactivity associated with DNA adducts. The absolute configuration of the various adducts was determined from the reaction of the (+)- and (-)-3,4-dihydrodiol after metabolic activation and the reaction of the anti- and syn-3,4-dihydroxy-1,2-epoxy-1,2,3,4-tetrahydrodibenz[a,h]anthracen e with DNA or with the individual deoxyribonucleotides. The main bay region adduct was identified as a deoxyguanosine adduct of (anti)-3S,4R-dihydroxy-1R,2S-epoxy-1,2,3,4-tetrahydrodibenz [a,h]anthracene, a metabolite of (-)-3,4-dihydroxy-3,4-dihydrodi- benz[a,h]anthracene. Anti bay region diolepoxide-deoxyguanosine adducts of DBA contributed to 17.7% and syn diolepoxide-derived deoxyguanosine adducts to 5.8% of adduct-associated radioactivity. The amount of bay region deoxyadenosine adducts was calculated to be 4%. For six of probably eight different deoxyadenosine adducts absolute stereochemistry could be assigned. 32P-Postlabelling experiments revealed a binding of 23 +/- 6 pmol/mg DNA for (-)-3,4-dihydrodiol and of 1.5 +/- 0.4 pmol/mg DNA for (+)-3,4-dihydrodiol of DBA.
Animals↗
Characterization of highly polar bis-dihydrodiol epoxide--DNA adducts formed after metabolic activation of dibenz[a,h]anthracene.
Dibenz[a,h]anthracene as well as a biologically important metabolite of dibenz[a,h]anthracene, namely the M-region dihydrodiol trans-3,4-dihydroxy-3,4-dihydrodibenz[a,h]anthracene were in addition to further metabolism to a bay region diol epoxide, extensively transformed to a distal bisdihydrodiol, 3,4,10,11-tetrahydroxy-3,4,10,11-tetrahydro-dibenz[a,h]anthracene, which exhibited after renewed metabolic activation high DNA binding efficiency, leading to a new class of very polar DNA adducts. After incubation of dibenz[a,h]anthracene with DNA in the presence of liver microsomes from Aroclor 1254 treated male Sprague-Dawley rats highly polar DNA adducts probably originating from 3R,4R,10R,11R-tetrahydroxy-3,4,10,11-tetrahydrodibenz[a,h]an thracene and 3R,4R,10S,11S-tetrahydroxy-3,4,10,11-tetrahydrodibenz[a,h]anthr ace ne were identified by reversed phase HPLC and by the 32P-postlabeling method. The adducts obtained were further characterized by comparing their fluorescence spectra with those obtained from 3,4,10,11-tetrahydroxy- 3,4,10,11-tetrahydrodibenz[a,h]anthracene and from 3,4-dihydroxy-3,4-dihydrodibenz[a]anthracene, the putative chromophore of the polar adduct. DNA adducts formed via 3S,4S,10S,11S-tetrahydroxy-3,4,10,11-tetrahydro- dibenz[a,h]anthracene were not found. After incubation of 14C-labelled dibenz[a,h]anthracene highly polar DNA adducts derived from the bisdihydrodiol contributed 38% to the adducts found in the HPLC profile. Bay region diol epoxide adducts represented a fraction of 25%. Using the 32P-postlabelling technique a higher DNA binding yield for the racemic bisdihydrodiol (38 +/- 12 pmol/mg DNA) was calculated than for the most active 3,4-dihydrodiol enantiomer, 3R,4R-dihydroxy-3,4- dihydrodibenz[a,h]anthracene (23 +/- 6 pmol/mg DNA).
Animals↗
Influence of dihydropyridine-type calcium agonists on hemodynamics and myocardial ischemia in isolated rabbit hearts.
Calcium (Ca) agonists like Bay k 8644 ((-)-S-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl) pyridine-5-carboxylate (CAS 93468-89-4), may represent a new principle in the treatment of heart failure. Because of marked vasoconstrictive properties, these agents may have a deleterious effect on myocardial ischemia (MI). It was however demonstrated that contractility enhancement and coronary flow (CF) reduction do not automatically enlarge MI. Therefore, we investigated the influence of Bay k 8644 (10(-8) mol/l) in comparison to ouabain (1.5 x 10(-7) mol/l) in non-arrhythmogenic concentrations on MI in electrically paced isolated rabbit hearts (Langendorff, constant pressure: 70 cm H2O, Tyrode solution, Ca2+ 1.8 mmol/l, 180 beats/min). MI was induced by coronary artery ligation and quantified by epicardial NADH-fluorescence. Left ventricular pressure (LVP) was significantly increased by ouabain (+10-20%) but slightly diminished by Bay k 8644 (-10%) (p < 0.05). CF reduction after Bay k 8644 (-30%) was more pronounced than after ouabain (-10%) (p < 0.05), but both substances did reduce relative CF (CF/LVP x heart rate) to the same extent (-20-30%) (p > 0.05). Nevertheless, ouabain did not significantly influence epicardial NADH-fluorescence area or intensity (p > 0.05), whereas MI was significantly enlarged by Bay k 8644 (+30%) (p < 0.05). It is concluded that in isolated rabbit hearts ouabain and Bay k 8644 might influence CF-distribution differently with a more pronounced diminuation of the nutritive CF induced by Bay k 8644.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
Skin anti-inflammatory activity of apigenin-7-glucoside in rats.
The effect of apigenin-7-glucoside on skin inflammation induced by different generators of reactive oxygen species and free radicals was studied. Skin inflammation in rats was induced by intradermal injection of glucose-oxidase (hydrogen peroxide), xanthine-oxidase/hypoxanthine (superoxide anion radical), and cumene hydroperoxide (peroxyl radical). Subsequent intradermal application of liposomal apigenin-7-glucoside inhibited in a dose dependent manner skin inflammation caused by xanthine-oxidase and cumene hydroperoxide. Glucose-oxidase induced dermatitis was not significantly inhibited. The results are in good agreement with the in-vitro superoxide anion radical and peroxyl radical scavenging properties of apigenin and indicate that its antioxidant properties contribute to the anti-inflammatory effect in this model system.
Animals↗
Estimating glucose absorption in peritoneal dialysis using peritoneal equilibration tests.
To determine peritoneal dialysis patients' dietary energy requirements, the glucose absorbed from the dialysate needs to be quantified. The currently accepted method of estimating glucose absorption is based on the average glucose absorption of 7 continuous ambulatory peritoneal dialysis (CAPD) patients (Grodstein, 1981). Peritoneal equilibration test curves have shown that modality and transport characteristics affect glucose absorption. To test a more accurate procedure for estimating glucose absorption, we compared two different methods of determining the actual glucose absorption: Grodstein formula: (11.3 xa-10.9) liters of dialysate, where xa is the average glucose concentration, and the D/D0 formula: (1-D/D0)xi, where xi is the initial glucose instilled, using 4-hour D/D0 for CAPD and dwell time D/D0 for automated peritoneal dialysis (APD). Twenty-four-hour glucose absorption was measured in 50 CAPD patients and 17 APD patients. Absorption was calculated from the glucose remaining in the 24-hour spent dialysate. Wilcoxon sign rank statistical analysis showed the D/D0 formula results to be closer to actual glucose absorbed (CAPD: p = 0.0153; APD: p = 0.0001). The D/D0 formula is individualized for patients' modality and membrane characteristics and easy to calculate from readily available information.
Absorption↗
The 24-hour D/P ratio is a convenient screen for identifying altered peritoneal transport rates.
Peritoneal transport characteristics (PTC) may change without peritonitis, surgery, or other insults. Identifying patients with these changes is essential in adjusting the dialysis prescription to achieve optimal peritoneal dialysis on a long-term basis. Frequent standard peritoneal equilibration tests (PETs) become impractical as the population in individual programs expands. The time demands are burdensome to the nursing staff as well as to the patient. The accuracy of fast PETs is dependent upon the patient's exact adherence to the protocol steps. Utilizing the 24-hour D/P as a marker for altered PTCs has improved the efficiency of our approach to repeating standard PETs and ensuring dialysis adequacy. For adequacy studies, pooled 24-hour dialysate is routinely collected in our unit. The 24-hour D/P ratio correlates well with extrapolations from original PET data and the patient's current dwell times. Discrepancies noted between the patient's actual D/P ratio and the patient's expected D/P ratio alert the clinician to possible PTC changes.
Biological Transport↗
Studies on lipoate effects on blood redox state in human immunodeficiency virus infected patients.
Several investigators have implicated that human immunodeficiency virus (HIV) infected patients have a compromised antioxidant defense system. Blood antioxidants are decreased and peroxidation products of lipids and proteins are increased in the patients. This may have pathophysiological implications, because antioxidants, such as glutathione, and reactive oxidants are involved in the regulation of the human immunodeficiency virus. Consequently it was suggested that HIV infected patients may benefit from antioxidant supplementation therapy. In a open and unblinded pilot study the short term effect of the natural antioxidant lipoate (Thioctacid) on blood antioxidants and peroxidation products was investigated in HIV positive patients (CDC IV). In the majority of the patients, lipoate increased plasma ascorbate (9 of 10 patients) total glutathione (7 of 7 patients), total plasma thiol groups (8 of 9 patients); T helper lymphocytes and T helper/suppressor cell ratio (6 of 10 patients), while the lipid peroxidation products malondialdehyde (8 of 9 patients) and 4-hydroxynonenal (7 of 9 patients) were decreased. The results of this pilot study indicate that lipoate supplementation changes the blood redox state of HIV infected patients. A prospective and longitudinal therapy study is warranted to investigate the long term effects of lipoate therapy on blood redox state, disease progression and incidence of opportunistic infections in HIV infected patients.
Adult↗