Biomedical subjects

A Lai

Publications and source records attributed to A Lai.

At least 55 records · Page 3Linked to original sources

PubMed1997

The interaction of DNA with intercalating agents probed by sodium-23 NMR relaxation rates.

We have investigated the changes of Na-23 NMR spin-lattice and spin-spin relaxation rates of Na-DNA in dilute aqueous solutions, induced by the intercalating drugs ethidium, propidium, 6,7-dihydro-pyrido[2',1':3,4]pyrazino[1,2-f]-phenanthridinediium dihydrate (dq2pyp) and by the electrostatic binder Mg2+. It has been found that the Na-23 spin-lattice relaxation is monoexponential, while the spin-spin relaxation follows a biexponential law. From the linear trends of the relaxation rates observed in the titration experiments of Na-DNA with the drugs we inferred the validity of a two-site model in the fast exchange limit. The relaxation rates of sodium in the bound state have been estimated by using the fraction of bound sodium ions per phosphate charge, predicted by the counterion condensation theory, and the number of sodium ions released per bound drug, calculated from salt dependent equilibrium binding studies. The results show that the addition of the competitors slow down the broad component of the spin-spin relaxation rate of bound sodium in the order dq2pyp approximately propidium < ethidium < Mg2+. This reduction is shown to be due mainly to the decrease of the quadrupolar coupling constant for the slow motions, thus indicating a decrease of the average electric field gradient at the sodium ions close to the DNA surface. We also show that the broad component of the spin-spin relaxation rate linearly correlates with the relative non-polyelectrolyte free energy. This result is discussed in terms of the non-polyelectrolyte interactions affecting R2bB, which can be partitioned into stacking interaction and interactions involving the molecular moieties of the intercalators exposed to the solvent in the minor groove.

Binding, Competitive↗

PubMed1997

Fulminant hepatic failure in murine hepatitis virus strain 3 infection: tissue-specific expression of a novel fgl2 prothrombinase.

Activation of the immune coagulation system has been implicated in the pathogenesis of fulminant liver failure caused by murine hepatitis virus strain 3 (MHV-3). The recent discovery of the fgl2 gene, which encodes for MHV-3-induced prothrombinase (fgl2 prothrombinase), allows for fundamental studies to determine the molecular basis for fulminant liver failure. Transcription of the fgl2 gene and translation of the protein it encodes were examined in the liver and other organs of susceptible mice following MHV-3 infection. No constitutive expression of the fgl2 gene or the fgl2 prothrombinase was detected. Within 12 to 24 h of MHV-3 infection, however, fgl2 gene transcripts were detected in large amounts in the liver, spleen, and lungs, all of which are rich in reticuloendothelial cells, but were only focally present in small amounts in the kidney and brain. There was sequential detection of fgl2 prothrombinase in the liver, where it was localized specifically to the endothelium of intrahepatic veins and hepatic sinusoids; this was allowed by fibrin deposition, which resulted in confluent hepatocellular necrosis. These results provide further evidence for the role of the selective expression of this novel fgl2 prothrombinase in the pathogenesis of MHV-3-induced fulminant liver failure.

Animals↗

PubMed1997

Regulation of p53 levels by the E1B 55-kilodalton protein and E4orf6 in adenovirus-infected cells.

The adenovirus type 5 243R E1A protein induces p53-dependent apoptosis in the absence of the 19- and 55-kDa E1B polypeptides. This effect appears to result from an accumulation of p53 protein and is unrelated to expression of E1B products. We now report that in the presence of the E1B 55-kDa polypeptide, the 289R E1A protein does not induce such p53 accumulation and, in fact, is able to block that induced by E1A 243R. This inhibition also requires the 289R-dependent transactivation of E4orf6 expression. E4orf6 is known to form complexes with the E1B 55-kDa protein and to function both in the transport and stabilization of viral mRNA and in shutoff of host cell protein synthesis. We demonstrated that the block in p53 accumulation is not due to the generalized shutoff of host cell metabolism. Rather, it appears to result from a mechanism targeted specifically to p53, most likely involving a decrease in the stability of p53 protein. The E1B 55-kDa protein is known to interact with both E4orf6 and p53, and as demonstrated recently by others, we showed that E4orf6 also binds directly to p53. Thus, multiple interactions between all three proteins may regulate p53 stability, resulting in the maintenance of low levels of p53 following virus infection.

Adenovirus E1B Proteins↗

PubMed1997

Pharmacokinetics of paclitaxel and carboplatin in a dose-escalating and dose-sequencing study in patients with non-small-cell lung cancer. The European Cancer Centre.

PURPOSE: To investigate the pharmacokinetics and pharmacodynamics of paclitaxel (P) and carboplatin (C) in a sequence-finding and dose-escalating study in untreated non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Fifty-five chemotherapy-naive patients with NSCLC were entered onto the pharmacokinetic part of a large phase I trial in which P was administered as a 3-hour infusion at dosages of 100 to 250 mg/m2, and C over 30 minutes at dosages of 300 to 400 mg/m2. Patients were randomized for the sequence of administration, first C followed by P or vice versa. Each patient received the alternate sequence during the second and subsequent courses. RESULTS: The most important hematologic toxicity encountered-was neutropenia. Hematologic toxicity was not dependent on the sequence in which P and C were administered, but there was cumulative neutropenia. Nonhematologic toxicities consisted mainly of vomiting, myalgia, and arthralgia. No sequence-dependent pharmacokinetic interactions for the P area under the concentration-time curve (P-AUC), maximal plasma concentration (P-Cmax), or time above a threshold concentration of 0.1 mumol/L (P-T > or = 0.1 mumol/L) were observed. However, there was a significant difference for the metabolite 6 alpha-hydroxypaclitaxel AUC (6OHP-AUC). Higher 6OHP-AUCs were observed when C was administered before P. The mean plasma ultrafiltrate AUC of C (CpUF-AUC) at the dosage of 300 mg/m2 for the sequence C-->P was 3.52 mg/mL.min (range, 1.94 to 5.83) and 3.62 mg/mL.min for the sequence P-->C (range, 1.91 to 5.01), which is not significantly different (P = .55). Of 45 assessable patients, there were five major responders (three complete responders and two partial responders). Four of five responses occurred at dosages above dose level 4 (P 175 mg/m2 + C 300 mg/m2). The median survival duration was best correlated with the P dose (4.8 months for doses < 175 mg/m2 v 7.9 months for doses > or = 175 mg/m2, P = .07; P-T > or = 0.1 mumol/L, 4.8 months for < 15 hours v 8.2 months for > or = 15 hours, P = .06). CONCLUSION: There was no pharmacokinetic-sequence interaction between C and P in this study. A clear dose-response relation with respect to response rate and survival was observed. The pharmacokinetic parameter P-T > or = 0.1 mumol/L was related to improved survival in this study.

Adult↗

PubMed1997

Phase I and pharmacologic study of the combination paclitaxel and carboplatin as first-line chemotherapy in stage III and IV ovarian cancer.

PURPOSE: To determine the maximum-tolerated dose for the combination paclitaxel and carboplatin administered every 4 weeks and to gain more insight into the pharmacokinetics and pharmacodynamics of this combination in previously untreated ovarian cancer patients. PATIENTS AND METHODS: Thirty-five chemotherapy-naive patients with suboptimally debulked stage III (tumor masses > 3 cm) and stage IV ovarian cancer were entered onto this phase I trial in which paclitaxel was administered as a 3-hour intravenous (IV) infusion at dosages of 125 to 225 mg/m2 immediately followed by carboplatin over 30 minutes at dosages of 300 to 600 mg/m2. A total of six courses was planned, followed by a second-look laparoscopy/laparotomy. Patients with a response and/or minimal residual disease at second-look laparoscopy received three additional courses. Twenty-six patients participated in the pharmacokinetic part of the study. RESULTS: The most important hematologic toxicity encountered was neutropenia. Neutropenia was more pronounced for the higher dose levels (DLs) and was cumulative. Thrombocytopenia was mild in the first eight DLs, but increased during the treatment courses. Nonhematologic toxicities consisted mainly of vomiting, neuropathy, fatigue, rash, pruritus, myalgia, and arthralgia. Dose-limiting toxicities (DLTs) in this trial were neutropenic fever, thrombocytopenia that required platelet transfusions, and cumulative neuropathy. Of 33 patients assessable for response, 26 major responders (78%, 20 complete response [CR] and six partial response [PR]) were documented. The maximal concentration (Cmax) of paclitaxel and the area under the concentration-time curve (AUC) were not different from the historical data for paclitaxel as a single agent. Retrospective analysis using a modified Calvert formula showed that the measured carboplatin AUCs in plasma ultrafiltrate (pUF) were 30% +/- 3.4% less than the calculated carboplatin AUC. Neutropenia was more pronounced than could be expected on the basis of the historical times above a threshold concentration greater than 0.1 mumol/L (T > or = 0.1 mumol/L) or 0.05 mumol/L (T > or = 0.05 mumol/L), and thrombocytopenia was less than could be expected from historical sigmoidal Emax models. CONCLUSION: The combination of paclitaxel 200 mg/ m2 and carboplatin 550 mg/m2 every 4 weeks is a well-tolerated treatment modality. The paclitaxel-carboplatin combination is highly active in stage III (bulky) and stage IV ovarian cancer. No indications for a pharmacokinetic drug-drug interaction between carboplatin and paclitaxel were found.

Adult↗

PubMed1997

[Precision of drug dilution techniques].

OBJECT: Evaluation of accuracy of three common dilution methods for drugs. EXPERIMENTAL PLAN: Perspective double blind investigation from March to June 1995. PLACE: Anaesthesia and Resuscitation Service of Children's Hospital of Iglesias (CA). METHODS: Forty dopamine at 2/1000 samples, obtained by dilution of dopamine at 40/1000 on sale with three different methods by five different operators, were analysed with a chromatography system in liquid phase at high pressure. RESULTS: Mean concentration with difference not exceeding 5% from the goal, are considered acceptable. Only one group of samples was found to be into these limits, but it was also the most dangerous for the high percentage of great mistakes in dilution. Although there are significant differences in the accuracy and safety of the three dilution methods, the highest and lowest final concentrations obtained differ very much from those estimated. CONCLUSIONS: It is suggested that drugs confections with proper dilution for different clinical uses might be on sale.

Indicator Dilution Techniques↗

PubMed1996

Binding of Ru(II) polyazaaromatic complexes to DNA: A 23Na NMR spin-lattice relaxation study.

The possibility of using sodium-23 spin-lattice relaxation rate measurements to probe the interaction modes of Ru11 polyazaaaromatic complexes with DNA is investigated. The following complexes are considered: Ru(phen)3(2+) (phen = 1.10-phenanthroline), Ru(phen)2HAT2+ (HAT = 1,4,5,8,9,12-hexaazatriphenylene), and Ru(diMeTAP)3(2+) (diMeTAP = 2,7-dimethyl-1,4,5,8-tetraazaphenanthrene). The addition of Ru(diMeTAP)3(2+) to a solution of NaDNA leads to a decrease in the sodium-23 spin-lattice relaxation rate (R1) similar to the effect observed upon addition of Mg2+. This indicates that Ru(diMeTAP)3(2+) interacts like Mg2+ with DNA and consequently that the electrostatic interaction dominates the association with DNA, Ru(phen)3(2+) and Ru(phen)2HAT2+ diminish R1 more efficiently than Mg2+, in a manner similar to ethidium bromide, which is known for its intercalation properties. Thus interactions other than electrostatic occur between these two complexes and DNA. These results are in agreement with data obtained from other techniques, according to which Ru(phen)3(2+) and Ru(phen)2HAT2+ are located partially inside the DNA double helix, in contrast to Ru(diMeTAP)3(2+) which remains in the ionic atmosphere around the phosphate backbone.

Animals↗

PubMed1996

Hepatic expression of hepatitis B virus genome in chronic hepatitis B virus infection.

The expression of hepatitis B virus (HBV) DNA in the liver was studied by nonisotopic in situ hybridization and correlated with liver histology, different phases in the natural evolution of chronic hepatitis B, and hepatic expression of HBV antigens in 251 Chinese patients with chronic HBV infection. A good correlation was found between the detection of HBV-DNA by in situ hybridization and serum HBV-DNA (P < .01). Chronic active hepatitis had the highest HBV-DNA detected in cytoplasm and nuclei, compared with livers showing minimal change, chronic persistent hepatitis, cirrhosis, and hepatocellular carcinoma. HBV-DNA in cytoplasm exceeded HBV-DNA in nucleus in all patients except in livers with hepatocellular carcinoma. Hepatic HBV-DNA correlated with disease activity (P < .02) and the correlation was highly significant with intralobular activity (P < .001). Patients in the early viral replicative phase of infection had higher levels of cytoplasmic and nuclear HBV-DNA compared with the late viral nonreplicative phase. Cytoplasmic and nuclear HBV-DNA correlated with hepatic expression of HBcAg and HBsAg (P < .05 in both cases), but not with HBeAg. These data indicate that hepatic expression of HBV-DNA follows the natural history of chronic HBV infection and is associated with active liver disease.

Adolescent↗

PubMed1995

Characterization of sorting signals in the beta-amyloid precursor protein cytoplasmic domain.

The beta-amyloid precursor protein (APP) is proteolytically processed to generate beta-amyloid protein, the principal protein component of neuropathological lesions characteristic of Alzheimer's disease. To investigate potential sorting signals in the cytoplasmic tail of APP, we transplanted APP cytoplasmic tail sequences into the cytoplasmic tail of the human transferrin receptor (TR) and showed that two sequence motifs from the APP cytoplasmic tail promote TR internalization. One sequence, GYENPTY, is related to the low density lipoprotein receptor internalization signal, FDNPVY, but also involves a critical glycine residue; the other, YTSI, conforms to the 4-residue tyrosine-based internalization signal consensus sequence. Furthermore, a chimeric molecule (APP-TR) consisting of the cytoplasmic domain of APP and the transmembrane and external domains of TR was rapidly internalized enabling the transport of iron into the cell at approximately 50% the rate of wild-type TR. Alanine scanning mutations indicated that the two sequences identified in transplantation experiments were required for internalization of the chimera. Metabolic pulse-chase experiments showed that the APP-TR chimeras were degraded in a post-Golgi membrane compartment within 2-4 h following normal glycosylation. Degradation was partially dependent upon the two internalization signals and was inhibited by ammonium chloride. A fraction of APP-TR chimeras traffic to a degradative endocytic compartment after appearing on the cell surface. Comparison of soluble APP released from cells expressing either full-length human APP or mutant APP with the sequence YENPTY deleted indicated that this sequence is required for sorting of full-length APP along similar trafficking pathways as the APP-TR chimera.

Amino Acid Sequence↗

PubMed1995

Ultrastructural findings in the vestibular end-organs of AIDS cases.

Neurotologic manifestations are apparent in human immunodeficiency virus (HIV) infection, but are poorly understood. Symptoms related to the vestibular system include episodes of vertigo, imbalance, ataxia, and nausea. Although patients present more often with hearing impairment, vestibular complaints are described and electrophysiologic studies indicate vestibular dysfunction in HIV-infected patients. Whether the disease involvement includes the central, or the peripheral nervous system has not been established. Ultrastructural analysis of vestibular end-organs obtained from HIV autopsy cases revealed pathologic changes in the labyrinth wall, the epithelial lining, and the receptor maculae and cristae. Cytologic changes in hair cells included inclusion bodies, viral-like particles, and hair bundle malformations. Epithelial lining cells, supporting cells, and connective tissue cells had inclusions and viral-like particles. These findings are consistent with those of a previous cochlear study demonstrating intracellular viral-like particles with the morphologic characteristics of HIV. Further cytologic evaluation of decalcified temporal bones and immunohistochemical analysis of freshly harvested HIV-infected temporal bones may provide further insight into the pathogenesis of viral-induced hearing loss and vestibular impairment.

Acquired Immunodeficiency Syndrome↗

PubMed1993

YTRF is the conserved internalization signal of the transferrin receptor, and a second YTRF signal at position 31-34 enhances endocytosis.

By functional analysis of mutant human transferrin receptors (TR) expressed in chicken embryo fibroblasts, we previously identified a tetrapeptide sequence, Y20TRF23, within the 61-residue cytoplasmic tail as the signal for high-efficiency endocytosis (Collawn, J. F., Stangel, M., Kuhn, L. A., Esekogwu, V., Jing, S., Trowbridge, I.S., and Tainer, J.A. (1990) Cell 63, 1061-1072). It has been inferred from other studies, however, that the TR internalization signal was localized to a much larger region, residues 7 through 26 (Girones, N., Alvarez, E., Seth, A., Lin, I-M., Latour, D.A., and Davis, R.J. (1991) J. Biol. Chem. 266, 19006-19012). Additionally, Tyr20 was reported to not be conserved in the Chinese hamster cytoplasmic tail sequence (Alvarez, E., Girones, N., and Davis, R.J. (1990) Biochem. J. 267, 31-35). In the studies reported here, we examined the effect of insertion of an extra copy of a YTRF sequence at three different locations within the human TR cytoplasmic domain and show that the insertion of another YTRF signal at position 31-34 in the wild-type TR, but not the other two locations, increases the rate of endocytosis 2-fold. Furthermore, introduction of YTRF at position 31-34 in an internalization-defective mutant receptor restores endocytosis to wild-type levels, indicating that YTRF signals at either positions 20-23 or 31-34 are necessary and sufficient to promote TR internalization and function in an independent and additive manner. We also report the complete primary structure of the Chinese hamster TR deduced from its cDNA sequence and show that the Tyr20 as well as the complete YTRF motif is conserved.

Amino Acid Sequence↗

PubMed1993

New concepts of rehabilitation following anterior cruciate reconstruction.

Can a knee joint with a torn ACL of 2 years' duration ever be able to return to high performance? Very unlikely indeed. Some realistic expectations follow: 1. The knee joint can never be normal after an ACL reconstruction. 2. Surgery must take place as early after the injury as possible, before secondary joint degeneration takes place. 3. The surgery must employ a tissue that best matches the normal ACL in strength and structure. 4. The surgery must involve as little trauma as possible while restoring knee joint mechanics. 5. Stress, although guarded, must be faced by the knee joint as soon as possible after surgery. 6. Progressive weight bearing starts immediately, combined with quadriceps isometrics. ROM of the knee joint, particularly full extension, is conserved and protected. 7. Progressive active ROM without formal resistance continues for 4 weeks. 8. Progressive formal resistance exercises continue for at least 1 year. 9. Sport-specific tasks commence at 16 weeks, depending on the requirement of the sport and the response of the individual athlete. 10. Recovery will plateau at several stages, with the final plateau at approximately 18 months. Knee instability is an exciting but perplexing problem. Although we have advanced profoundly from the era of Jones, Smiley, and others, we still face many of the same challenges as our predecessors. New technology should not fool us. We are still addressing a major structural failure within the knee joint. Our attempts have been non-surgical and surgical, with repair, reconstruction, and replacement. However, fundamental to all of these hopes has been the reconditioning of the extremity after ACL surgery. Can we do better than our forefathers like Licht and others? No one is certain. This article offers an approach, in some areas our approach, but should not be perceived as a cookbook. Individual responses by our patients, athletes, dictate whether any protocol is too hasty or tardy. It is fundamental that we listen to our patients objectively and analyze the knee as it returns from the surgical aggression. The ultimate success of the rehabilitation process will be based on the marriage of science and realistic expectations.

Analgesia↗

PubMed1992

Analysis of sodium-23 nuclear magnetic resonance spin-lattice relaxation for the study of the intracellular sodium state.

Sodium-23 Nuclear Magnetic Resonance relaxation spectroscopy has been used to investigate the state of intracellular Na+ in control and CCl4-treated rat livers. The analysis of spin-lattice relaxation rates at 1.88 and 7.07 Tesla based on a two-site exchange model led to estimates of pertinent modulation times. Also it has been found that a relatively high quantity of Na+ (PB = 1.59 x 10(-2)) is bound to charged sites of intracellular macromolecules or membranes. The degree of binding strongly decreases in CCl4 treated rat livers.

Animals↗

PubMed1992

Protein deficiency and excess lipid synergistically augmented lipid peroxidation in growing rats.

The influence of dietary protein and lipid on superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH) and tissue lipid peroxidation, as measured by thiobarbituric acid-reactive substances (TBARS), was investigated in post-weaning male Wistar rats, fed either a diet containing 5% or 20% corn oil with 5%, 10% or 20% soy protein isolate (SPI) for four weeks. TBARS concentrations in 5% corn oil group was highest in 5% SPI group for all organs, followed by 10 and 20% SPI groups in the liver and 10 and 20% SPI groups in other organs. High lipid diet significantly increased TBARS formation in the liver of 10% SPI group. The liver and kidney SOD and GPx activities were higher in 5% and 10% SPI groups than in 20% SPI group, suggesting an augmented formation of radical substrates for these enzymes in low protein groups. Organ GSH concentrations did not show a linear correlation with dietary protein level. These results suggest that protein deficiency along with high lipid intake accelerates the peroxidative damage of the tissues by increasing oxy-radical formations and/or decreasing the defense mechanism.

Animals↗

PubMed1991

Proton and tritium NMR relaxation studies of peptide inhibitor binding to bacterial collagenase: conformation and dynamics.

The interaction of succinyl-Pro-Ala, a competitive inhibitor of Achromobacter iophagus collagenase, with the enzyme was studied by longitudinal proton and tritium relaxation. Specific deuterium and tritium labeling of the succinyl part at vicinal positions allowed the measurement of the cross-relaxation rates of individual proton or tritium spin pairs in the inhibitor-enzyme complex as well as in the free inhibitor. Overall correlation times, internuclear distances, and qualitative information on the internal mobility in Suc1 (as provided by the generalized order parameter S2) could be deduced by the comparison of proton and tritium cross-relaxation of spin pairs at complementary positions in the -CH2- CH2- moiety as analyzed in terms of the model-free approach by Lipari and Szabo. The conformational and motional parameters of the inhibitor in the free and enzyme-bound state were directly compared by this method. The measurement of proton cross-relaxation in the Ala residue provided additional information on the inhibitor binding. The determination of the order parameter in different parts of the inhibitor molecule in the bound state indicates that the succinyl and alanyl residues are primarily involved in the interaction with the enzyme activity site. The succinyl moiety, characterized in solution by the conformational equilibrium among the three staggered rotamers--i.e., trans: 50%; g+: 20%; g-: 30%--adopted in the bound state the unique trans conformation.

Alcaligenes↗

PubMed1990

Alkyl hydroperoxide reductase from Salmonella typhimurium. Sequence and homology to thioredoxin reductase and other flavoprotein disulfide oxidoreductases.

The DNA sequence of the Salmonella typhimurium ahp locus was determined. The locus was found to contain two genes that encode the two proteins (C22 and F52a) that comprise the S. typhimurium alkyl hydroperoxide reductase activity. The predicted sequence of the F52a protein component of the alkyl hydroperoxide reductase was found to be highly homologous to the Escherichia coli thioredoxin reductase protein (34% identity with many conservative substitutions). The homology was found to be particularly striking in the region containing the redox-active cysteines of the thioredoxin reductase molecule, and among the identities were the redox-active cysteines themselves. Aside from the strong similarity to thioredoxin reductase, overall homology between the F52a protein and other flavoprotein disulfide oxidoreductases such as glutathione reductase, dihydrolipoamide dehydrogenase, and mercuric reductase was found to be rather limited, and the conserved active site segment common to the three proteins was not observed within the F52a protein. However, three short segments that have been implicated in FAD and NAD binding were found to be conserved between the F52a protein and the other disulfide reductases. These results suggest that the alkyl hydroperoxide reductase is the second known member of a class of disulfide oxidoreductases which was represented previously by thioredoxin reductase alone; they also allow the putative assignment of several functional domains.

Amino Acid Sequence↗

PubMed1990

The role of ferritin and hemosiderin in the MR appearance of cerebral hemorrhage: a histopathologic biochemical study in rats.

A rat model of cerebral hemorrhage using stereotaxic injection of blood into the right basal ganglia was developed to investigate the influence of iron metabolism on the appearance of cerebral hemorrhage on MR images. Images of in vitro fixed brain sections stained specifically for different iron-storage substances, ferritin and hemosiderin, created by digitization of the pathology sections using an Eikonix CCD camera, were compared with the in vivo MR images of late-phase hematomas. Areas of the pathologic and MR features of the lesions were quantitatively correlated. The single-slice MR images were obtained with the use of T1- and T2-weighted spin-echo pulse sequences, as well as T2-weighted spin-echo pulse sequences in which the 180 degrees refocusing pulse was offset from the center of the echo time; this was termed an asymmetric spin-echo pulse sequence. The symmetric and asymmetric T2-weighted images allowed the calculation of line-width images, which emphasize line broadening from intravoxel magnetic field inhomogeneities that arise from the presence of iron-containing substances. From biochemical and histochemical staining, we conclude that at least two iron-storage substances are present in the late phase of resolving cerebral hematomas. Ferritin has a wider distribution than hemosiderin, showing a similar distribution to the MR signal changes of the calculated line-width images. Line-width mapping is a sensitive means of detecting magnetic field inhomogeneities caused by the magnetic susceptibility differences introduced by the aggregation of these iron-storage substances.

Animals↗

PubMed1989

An Na-23 and P-31 NMR investigation of sonicated cardiolipin sodium salt in aqueous medium.

Na-23 and P-31 nuclear magnetic resonance was used to investigate the structure and dynamics of Na+ trapped in the enclosed aqueous spaces of unilamellar vesicles of Cardiolipin sodium salt. After sonicated Cardiolipin sodium salt forms a clear solution in aqueous medium and gives rise to a narrow, isotropic P-31 NMR line. This line was attributed to the presence of either vesicles or more complex liquid crystalline structures showing superposed-signals for inner and outer phosphate groups. The use of paramagnetic shift reagent Dy(PPPi)2 made it possible to observe only the line of the phosphate groups arranged within the structures. From an analysis of the spin-lattice relaxation parameters of Na-23 at 21.04 MHz and 52.6 MHz, the correlation time tau = 1.3 x 10(-9) sec was estimated. It was then possible to calculate the value of 1.9 MHz for the quadrupolar coupling parameter. These findings were interpreted in terms of the occurrence of specific bindings between Na+ and the phosphate moieties within the unilamellar structures of Cardiolipin.

Cardiolipins↗