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D E Wilcox

Publications and source records attributed to D E Wilcox.

34 records · Page 2Linked to original sources
PubMed1989

Decomposition and specific exchange of the trans-cyanide ligand on nitroprusside is facilitated by hemoglobin.

Most investigators agree that sodium nitroprusside (SNP) undergoes biotransformation in vivo to release free cyanide (CN-). Despite a demonstrated reactivity of SNP toward oxyhemoglobin (HbO2) in vitro, that reaction is probably not the major cause for CN- release in vivo. An unknown reaction in various vascular beds inactivates SNP more rapidly than the reaction in blood, but both result in the release of free CN-. Recently it has been claimed that SNP is stable in blood and that the apparent CN- release is an artifact due to photodecomposition of SNP during CN- analyses. In this study the release of free CN- from SNP was followed over 3 hr of incubation in plain buffer, in suspensions of red blood cells (RBC), in lysates, and in solutions of HbO2 purified by isoelectric focusing and shown to be free of methemoglobin (MetHb), valency hybrid species, and reduced glutathione (GSH). In each case the mixtures containing HbO2 released significantly more CN- than plain buffer where CN- release was at the limit of sensitivity of the method. Moreover, in the order of RBC, purified HbO2 solutions and lysates, each preparation released significantly more CN- in 1 hr than the preceding one. In lysates the reaction had gone to completion by 3 hr. Using 13C nuclear magnetic resonance (NMR) spectroscopy, SNP was shown to be inert to CN- exchange in solutions of Na13CN, but when GSH or MetHb was added, an exchange reaction occurred between the trans-CN- of SNP and 13CN- in solution. The same reaction proceeded even more rapidly in the presence of HbO2. The results of this study show that in the presence of GSH, MetHb and particularly in the presence of HbO2, SNP readily exchanges its trans-CN- ligand with excess free CN-. This reaction is believed to represent an obligatory precursor step in the total decomposition of SNP which occurs in the absence of free CN-, but in the presence of RBC, solutions of HbO2, and lysates. It appears that excess free CN- halts total decomposition at the stage of trans-CN- labilization.

Cyanides↗
PubMed1988

Generation of valency hybrids and nitrosylated species of hemoglobin in mice by nitric oxide vasodilators.

The hemoglobin fraction of blood samples from C57BL/6 male mice was purified by column chromatography and subjected to isolectric focusing (IEF) across a pH gradient. Densitometric scanning of the IEF gel showed the presence of a single peak corresponding to the fully reduced tetramer, H, or (alpha 2+ beta 2+)2. Twenty minutes after an ip injection of 1.1 mmol/kg NaNO2 blood samples treated the same way showed four peaks corresponding to the species: H = 43%, X or (alpha 2+ beta 3+)2 = 10%, Y or (alpha 3+ beta 2+)2 = 33%, and M or (alpha 3+ beta 3+)2 = 14%. In contrast blood samples from control CD-1 male mice showed the presence of three IEF distinct peaks which were all believed to be H valency forms, and six distinct peaks were seen after treatment in vivo with NaNO2. Thus, the C57BL/6 mice yield patterns similar to those observed after in vitro treatment of human red cells with NaNO2 (H. Kruszyna, R. Kruszyna, R. P. Smith, and D. E. Wilcox, 1987b, Toxicol. Appl. Pharmacol. 91, 429-438), and the CD-1 mice are a much less satisfactory model. The appearance and disappearance of the species X, Y, and M over time after ip injection of 1.1 mmol/kg NaNO2 or hydroxylamine HCl were followed in C57BL/6 mice by the technique of IEF. In each case the patterns were consistent with previously established patterns for the respective methemoglobinemias as determined by absorption spectrophotometry, and they were consistent with the suggestion that two pathways exist for the oxidation of H and for the reduction of M which proceed through X and Y, respectively. By using electron paramagnetic resonance (EPR) spectroscopy, we were also able to follow with time the concentration of nitrosylated heme (NO-heme) on reduced subunits in both mouse strains. The peak for the NO-heme coincided in time with the peak methemoglobinemia as determined by either IEF or absorption spectrophotometry. EPR was also used to determine NO-heme in CD-1 mice after injection of a series of NO-vasodilators with and without methylene blue (MB). Low, but clearly detectable amounts of NO-heme were found in the blood of animals given all xenobiotics tested including NaNO2, hydroxylamine HCl, glyceryl trinitrate, hydralazine, sodium nitroprusside, and sodium azide. MB has little effect on the response, and no NO-heme could be detected in control mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Palmoplantar keratoderma, nail dystrophy, and hereditary motor and sensory neuropathy: an autosomal dominant trait.

Autosomal dominant inheritance of a syndrome comprising palmoplantar keratoderma, nail dystrophy, and hereditary motor and sensory neuropathy (HMSN) was observed in three generations of one family. Nail dystrophy affected the toe and fingernails; it was present at birth or developed during early childhood. Palmoplantar keratoderma became apparent in later childhood. Each subject with nail dystrophy and keratoderma also had clinical or electrophysiological evidence of axonal neuropathy.

Child↗
PubMed1987

Red blood cells generate nitric oxide from directly acting, nitrogenous vasodilators.

Human red blood cells (RBC) incubated under nitrogen with methylene blue and glucose at physiological temperature and pH can be used to test for the biotransformation of nitrogenous vasodilators to nitric oxide (NO). The NO generated was trapped as nitrosylated heme by reduced subunits (hemeII) on various hemoglobin valency species and quantified by electron paramagnetic resonance spectroscopy. It was possible to separate the various valency species of hemoglobin present in the mixture as (alpha 2 + beta 2)2, (alpha 2 + beta 3+)2, (alpha 3 + beta 2+)2, or (alpha 3 + beta 3+)2 by isoelectric focusing (IEF) unless cyanide (from nitroprusside) or azide was present in the mixture. These anions bind tenaciously to oxidized subunits (hemeIII) and prevent the separation of the various species by IEF. The fully oxidized tetramer, (alpha 3 + beta 3+)2, does not bind NO, but the other three species have hemeII units which can be nitrosylated. In the absence of cyanide or azide the valency species could be separated by IEF, and it was possible to quantify the degree of nitrosylation on each individual species. The various agents tested (nitrite, glyceryl trinitrate, hydroxylamine, hydralazine, nitroprusside, and azide) produced different patterns of valency species and degrees of nitrosylation of hemeII. When hemeIII ligands were present or in cases of very low yields, it was still possible to quantify the total concentration of NO-hemeII in the mixture. Thus, the method could still be used to test for NO formation. All of the so-called NO vasodilators tested yielded detectable amounts of NO in the system.

Electron Spin Resonance Spectroscopy↗
PubMed1987

Utilization prediction for helicopter emergency medical services.

As the number of helicopter emergency medical services (HEMS) programs continues to expand rapidly, the need for an accurate, readily obtainable, inexpensive method of utilization prediction for these services has become apparent. Accurate volume and case mix prediction for these services are increasingly important as financial constraints become more severe. All previous methods of utilization prediction based on experiences of individual services or accident statistics have been either inaccurate, costly, or difficult to obtain in a relatively short period of time. Prediction of HEMS utilization requires consideration of many significant, simultaneous factors, in addition to patient needs based on population statistics. Through use of a survey of all hospital-based helicopter emergency service programs and published census data, this study analyzed factors relating to helicopter program volume and case mix, providing insight as to why previous methods utilizing total population were inaccurate. A more accurate yet simple and inexpensive method of utilization prediction for HEMS was developed.

Aircraft↗
PubMed1987

Nitrite conversion to nitric oxide in red cells and its stabilization as a nitrosylated valency hybrid of hemoglobin.

The authors describe a method for the preparation, isolation and purification from human red blood cells of a stable form of hemoglobin containing both oxidized and reduced subunits. After isoelectric focusing across a pH gradient, it occupies the same position as the synthetically reconstituted or chemically generated species, (alpha 2+ beta 3+)2 (I). Unlike its synthetic or chemically generated counterpart, however, it (HbX) does not bind oxygen. A different method for the preparation in situ of the (alpha 3+ beta 2+)2 valency hybrid results in a pigment with chemical and spectral properties identical with those ascribed to its synthetically reconstituted counterpart, and both bind oxygen. HbX is generated in highest yield when red cells are incubated under N2 in the presence of glucose, methylene blue and nitrite for several hours. Its visible absorption spectrum differs from that reported for I, and it reacted very slowly with ferricyanide. Exposure to CO did not result in spectral shifts over that for HbX in air, but spectral shifts were produced with CO exposure of (alpha 3+ beta 2+)2. HbX had an inositol hexaphosphate difference-binding spectrum quite unlike that described for I. HbX also had a distinctive electron paramagnetic resonance spectrum that shifted after inositol hexaphosphate addition with a new three-line hyperfine pattern. Both spectra were characteristic for an unpaired electron in an iron-centered orbital with a hyperfine coupling to the nitrogen nuclear spin of a nitrosyl ligand on heme iron. The authors conclude that HbX is a form of I, but it has NO bound to its reduced subunits.

Electron Spin Resonance Spectroscopy↗
PubMed1986

Duchenne muscular dystrophy due to familial Xp21 deletion detectable by DNA analysis and flow cytometry.

We report two male cousins with Duchenne muscular dystrophy (DMD) in whom cytogenetic studies have shown a small interstitial deletion at Xp21. The lesion is readily detectable in patients and carriers by flow cytometry which indicates that approximately 6000 kb of DNA are deleted in each case. The DNA markers OTC, C7, and B24 are present in the deleted X chromosome but 87-8, 87-1, and 754 are absent. Despite apparently identical deletions one affected boy has profound mental handicap while the other is only mildly retarded. The results confirm the assignment of familial DMD to Xp21 and illustrate the value of flow cytometry in improving the precision of chromosome analysis. We have also undertaken flow cytometry in a cell line from a previously reported DMD patient with a de novo Xp21 deletion who had, in addition, chronic granulomatous disease, retinitis pigmentosa, and the McLeod syndrome. The results indicate that the amount of DNA deleted from the X is similar in both families despite the striking differences in phenotype.

Child↗
PubMed1985

Multipoint linkage analysis of the short arm of the human X chromosome in families with X-linked muscular dystrophy.

Sixteen three generation families from the West of Scotland with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) have been studied using the Xg blood group and seven cloned DNA sequences which recognise DNA polymorphisms on the short arm of the X chromosome (Xp). Linkage has been established between DMD and probe 754 with a maximum lod score (Z) of 4.47 at a recombination fraction (theta) of 0.04. DMD has also been linked to probe 99-6 (Z = 3.75, theta = 0.03). Combining the data in this study with that of previously published work has established linkage between DMD and L1.28 (Z = 4.42, theta = 0.17) and altered the linkage estimate between BMD and L1.28 (Z = 3.50, theta = 0.22). An approximate order for the loci has been deduced by the study of recombinant chromosomes in phase known families informative for three or more loci. The proposed order is centromere--L1.28--754--DMD/BMD--99-6--D2--782--Xg. These results conclusively map both DMD and BMD to the central region of Xp and add weight to the original suggestion that they may be allelic.

Alleles↗
PubMed1977

An audio urine-glucose analyzer for blind diabetics.

At the instigation of one of the authors (J.M.)--a young man whose blindness is due to diabetic retinopathy--a urine-glucose analyzer was designed and constructed. Its purpose and function enable him to test his urine himself (free of dependence on thers for this service) and, thereby, he can then determine and administer his doses of insulin. He and other young blind diabetics may value the degree of freedom from dependence on others than the analyzer provides and feel it helps them to be able to work and care for themselves. A description of the instrument instructions for its use, and a summary of about 20 months' experience with it are submitted.

Blindness↗
PubMedDate not supplied

Effect of cyanide on the reaction of nitroprusside with hemoglobin: relevance to cyanide interference with the biological activity of nitroprusside.

The reaction of sodium nitroprusside (SNP) with deoxyhemoglobin (Hb) results in two distinct EPR-detectable species, the one-electron-reduced nitroprusside ion [(CN)5FeNO]3- and nitrosylhemoglobin (HbNO). In the presence of excess cyanide (CN-) only the signal for [(CN)5FeNO]3- is observed. Thus, while free CN- does not interfere with Hb reduction of SNP, it prevents transfer of the NO moiety to Hb. Electrolytic reduction of SNP under similar conditions, however, leads to [(CN)5FeNO]3- and a small amount of [(CN)4FeNO]2- resulting from loss of the CN- trans to the NO. Excess free CN- shifts the equilibrium between these two species toward [(CN)5FeNO]3-, thereby reducing the concentration of [(CN)4FeNO]2-. Thus, [(CN)4FeNO]2- appears to be responsible for the transfer of NO to Hb. Consistent with this mechanism, both [(CN)5FeNO]3- and [(CN)4FeNO]2- are observed when SNP is added to erythrocyte lysates. Under these conditions HbNO is formed more rapidly due to the higher concentration of the latter species with the labile NO. This observation suggests that red blood cell constituents capable of binding CN- shift the equilibrium between the reduced SNP ions toward [(CN)4FeNO]2-. In the reaction of reduced glutathione (GSH) with SNP, [(CN)5FeNO]3- is formed as well as low concentrations of an EPR-detectable GSH-SNP adduct. Excess free CN- introduces a lag in the appearance of these signals, suggesting that GSH mediates SNP reduction by a different mechanism from that of Hb, although it too is inhibited by CN-.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMedDate not supplied

Analysis of deletions in DNA from patients with Becker and Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder for which the biochemical defect is as yet unknown. Recently, two cloned segments of human X-chromosome DNA have been described which detect structural alterations within or near the genetic locus responsible for the disorder. Both of these cloned segments were described as tightly linked to the locus and were capable of detecting deletions in the DNA of boys affected with DMD. In an attempt to determine more precisely the occurrence of these deletions within a large population of DMD patients and the accuracy of one of the segments, DXS164 (pERT87), in determining the inheritance of the DMD X chromosome, the subclones 1, 8 and 15 were made available to many investigators throughout the world. Here we describe the combined results of more than 20 research laboratories with respect to the occurrence of deletions at the DXS164 locus in DNA samples isolated from patients with DMD and Becker muscular dystrophy (BMD). The results indicate that the DXS164 locus apparently recombines with DMD 5% of the time, but is probably located between independent sites of mutation which yield DMD. The breakpoints of some deletions are delineated within the DXS164 locus, and it is evident that the deletions at the DMD locus are frequent and extremely large.

Chromosome Deletion↗
PubMedDate not supplied

Direct measurement of dimensional accuracy with three denture-processing techniques.

The Michigan Computer-Graphics Coordinate Measurement System (MCGCMS) was used to determine the dimensional accuracy of dentures processed by three different techniques: conventional heat compression, microwave, and visible-light activation. Standardized dentures were fabricated from casts made in an RTV silicone mold. All casts were duplicated with hydrocolloid and 42 dentures were made (ie, 14 dentures for each technique). The MCGCMS measured 22 points on two frontal planes to compare master casts to dentures. The results showed no significant difference in overall dimensional accuracy. At specific sites, however, the visible-light-activated technique produced significantly more flange distortion than did either the conventional or microwave techniques.

Acrylic Resins↗