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Biomedical subjects

R G Wilkins

Publications and source records attributed to R G Wilkins.

At least 19 recordsLinked to original sources
PubMed2000

Using a system of diagnosis and treatment planning to reduce stress.

Because a thorough system of treatment planning was used, the dentist was able to change the patient's smile and discuss potential problems with the patient before treatment. This discussion allowed the patient and dentist to proceed with treatment knowing that any problems would be dealt with if they arose. The work-up of the case also made it easier for the laboratory to know exactly what outcome the dentist and patient were expecting. This enhanced communication allowed the case to proceed with a minimum of stress for everyone.

Adult↗
PubMed1997

Levels of expression of P-selectin, E-selectin, and intercellular adhesion molecule-1 in coronary atherectomy specimens from patients with stable and unstable angina pectoris.

Unstable angina occurs when atherosclerotic plaque ruptures. Recent evidence suggests a role for inflammation in this process. Leukocyte-endothelial cell interactions are important in inflammation and are regulated by cell adhesion molecules. This study was designed to examine the vascular expression of cell adhesion molecules and cytokines in patients with unstable angina. Directional coronary atherectomy was performed in patients with unstable and stable angina. Expression of the cell adhesion molecules P-selectin, E-selectin, and intercellular adhesion molecule-1 in the tissue obtained was examined using immunohistochemistry. In addition, expression of the cytokines tumor necrosis factor-alpha and interleukin-1beta, which participate in the regulation of cell adhesion molecule expression, was also examined. Atherectomy specimens had significantly greater P-selectin expression from patients with unstable angina than from patients with stable angina. P-selectin expression was observed primarily on endothelial cells. There were no differences in any of the other factors between patients with unstable and stable angina. In addition, other clinical and angiographic variables were not associated with differential expression of any of the cell adhesion molecules or cytokines. These results indicate a possible role for P-selectin in the process of unstable angina.

Adult↗
PubMed1989

Hemodynamic and oxygen transport response to modified fluid gelatin in critically ill patients.

The hemodynamic and oxygen transport effects of the rapid infusion of 500 ml of modified fluid gelatin, an artificial colloid widely used in Europe, were studied in a group of critically ill patients suffering from cardiovascular instability. Oxygen consumption tended to increase. There were no significant changes in heart rate, shunt fraction, or systemic vascular resistance index. There were significant increases in mean arterial pressure, pulmonary artery wedge pressure, stroke index, cardiac index, and oxygen delivery. There were significant decreases in Hgb concentration and arterial oxygen content. The overall circulatory effects of modified fluid gelatin are beneficial.

Adult↗
PubMed1989

Kinetics and thermodynamics of the reaction of deoxyhemerythrin with nitric oxide.

Deoxyhemerythrin reacts with NO to form a 1:1 adduct shown spectrophotometrically. The kinetics of the formation have been studied directly by stopped-flow measurements at four different temperatures (0.0-23.6 degrees C). The kinetics of the dissociation have been studied, also by stopped-flow techniques, at five different temperatures (4.0-35.1 degrees C) using three different scavengers [Fe(II)(edta)2-, O2 and sperm whale deoxymyoglobin], which gave similar values. For the formation kf = (4.2 +/- 0.2) x 10(6) M-1 s-1, delta Hf not equal = 44.3 +/- 2.3 kJ mol-1, delta Sf not equal to = 30 +/- 8 J mol-1 K-1 and for the dissociation kd = 0.84 +/- 0.02 s-1, delta Hd not equal to 95.6 +/- 2.1 kJ mol-1 delta Sd not equal to = 74 +/- 7 J mol-1 K-1 (25 degrees C, I = 0.2 M and pH 7-8.1). From the kinetic data the thermodynamic data for the formation of HrNO were calculated: Kf = (5.0 +/- 0.3) x 10(6) M-1, delta H = -51.3 +/- 3.1 kJ mol-1 and delta S = -44 +/- 11 J mol-1 K-1 (25 degrees C). The kinetic data suggest that NO occupies the same iron(II) site in deoxyhemerythrin as oxygen does. The equilibrium constant for the formation of Fe(II)(edta)(NO)2- has been redetermined: K1 = (1.45 +/- 0.07) x 10(7) M-1, delta H = -77.5 +/- 1.5 kJ and mol-1 and delta S = -123.5 J mol-1 K-1 (25 degrees C).

Biotransformation↗
PubMed1988

Oxygen consumption following trauma: a reappraisal in severely injured patients requiring mechanical ventilation.

Oxygen consumption (VO2) immediately following major injury in man has been said to be reduced. The evidence for this is poor. We have therefore measured VO2 soon after major injury in 16 patients. VO2 was reduced in only two patients, within the normal range in four and increased in ten. VO2 was maintained by increased oxygen extraction in six patients leading to low levels of mixed venous oxygen saturation. There is no evidence for an 'ebb phase' response in man.

Adolescent↗
PubMed1988

Reversal of intractable septic shock with norepinephrine therapy.

Ten patients with severe septic shock were studied. After plasma volume expansion to an optimal pulmonary artery wedge pressure, above which there were no further increases in cardiac index, all patients remained hypotensive and oliguric. The arterial hypotension was unresponsive to increasing doses of dopamine and dobutamine alone and to a fixed combination of both. In all patients studied, infusion of norepinephrine alone reversed the hypotension and increased significantly the mean arterial pressure, systemic vascular resistance and left ventricular stroke work index (p less than .005). There were only minor increases in heart rate. Oxygen transport indices measured in six patients demonstrated variable alterations in oxygen delivery and consumption.

Adult↗
PubMed1987

Acid-assisted anion interaction with deoxyhemerythrin.

The interaction of N3-, CNO- and F- with deoxyhemerythrin was monitored from pH 6 to 9 and 3 degrees C to 25 degrees C at an ionic strength 0.5 M (Na2SO4) by using competition with O2. A proton is involved in forming the adduct and is not lost from the protein even at pH values as high as 9. Thermodynamic and kinetic parameters for the interaction of each anion are obtained. It is considered that the proton is introduced as the acid HX and the corresponding parameters for the reaction of HX with deoxyhemerythrin are calculated. These are compared with those for the O2 reaction with deoxyhemerythrin. The adducts are remarkably inert and have dissociation half-lives ranging from 7 s (N3-) to 70 s (CNO- and F-) at 25 degrees C. This stability is ascribed to protonation of a bridged hydroxy group or even bridge-breakage.

Acids↗
PubMed1987

Atrial fibrillation precipitated by acute hypovolaemia.

Six patients with varying degrees of acute cardiorespiratory failure were seen. All patients deteriorated noticeably when rapid atrial fibrillation developed. In all patients intravenous digitalis failed to slow the ventricular response, and in three patients misguided attempts at electrical cardioversion failed. Haemodynamic monitoring showed a normal or low pulmonary artery occlusion pressure in all patients. Controlled expansion of plasma volume was associated with an immediate slowing of the heart rate in all patients, and the heart rate in all patients returned to sinus rhythm within 30 minutes of transfusion. It is suggested that hypovolaemia in critically ill patients may contribute to the development of atrial fibrillation.

Atrial Fibrillation↗
PubMed1987

Danger of using core/peripheral temperature gradient as a guide to therapy in shock.

During the treatment of 26 shocked patients, measurements were made of the central blood to peripheral skin temperature gradient. No significant correlation was found between this gradient and cardiac index (CI), or systemic vascular resistance (SVR) or its index (SVRI). There was no significant correlation between the change in gradient and the changes in CI, SVR or SVRI in any single patient. We conclude that it is incorrect to base any judgment of a patient's hemodynamic status on a core/peripheral temperature gradient during shock, and it is irrational to initiate therapy based on this measurement.

Cardiac Output↗
PubMed1987

Marcain shakes.

Explore the source record for details and available documents.

Bupivacaine↗
PubMed1986

Postoperative backache: the use of an inflatable wedge.

An inflatable wedge was used to support the lumbo-sacral curve of patients undergoing anaesthesia and surgery in either the supine or lithotomy position. Of the operative factors investigated, the presence of a wedge was the only one found to have a useful influence on the incidence of postoperative backache, which was reduced significantly (P less than 0.001).

Adolescent↗
PubMed1985

Interaction of zinc ions with arsanilazotyrosine-248 carboxypeptidase A.

The interaction between arsanilazotyrosine-248 carboxypeptidase A ([(Azo-CPD)Zn]) and excess zinc ions has been studied by stopped-flow and spectrophotometric methods at pH 8.2 and 7.7, I = 0.5 M (NaCl), and 25 degrees C. When excess zinc ions bind to arsanilazotyrosine-248 carboxypeptidase A, the characteristic red color, which arises from the intramolecular complex of the arsanilazotyrosine-248 residue with the active site zinc of the enzyme, changes to yellow with the inhibition of peptidase activity of the enzyme. Excess zinc ions have two binding sites for arsanilazotyrosine-248 carboxypeptidase A, and the binding constants of the first site (3.9 X 10(5) M-1 at pH 8.2; 7.1 X 10(4) M-1 at pH 7.7) are much larger than those of the second site (1.8 X 10(3) M-1 at pH 8.2; 7 X 10(2) M-1 at pH 7.7). The binding of excess zinc ions to the first site is completely correlated with the inhibition of the enzyme peptidase activity and the color change of the enzyme. The results can be understood in terms of zinc ions reacting with only one of three conformational states of arsanilazotyrosine-248 carboxypeptidase A [Harrison, L. W., Auld, D. S., & Vallee, B. L. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 4356].(ABSTRACT TRUNCATED AT 250 WORDS)

Carboxypeptidases↗
PubMed1985

The interaction of hemerythrin with sodium dodecyl sulfate and the release of iron from the product with desferrioxamine B.

The interactions with sodium dodecyl sulfate (SDS) of methemerythrin, the anionic derivatives and oxyhemerythrin from Phascolopsis gouldii have been examined at 25 degrees C, I = 0.5 M and pH 6.3 and 7.8. Absorbance changes in the 350-500 nm range were used to monitor the rates. The denaturation is slow (k = 10(-2)-10(-3) s-1) and only slightly dependent on SDS concentration. Perchlorate is a very effective inhibitor of the SDS reaction with methemerythrin, and it is concluded that rapid binding of SDS near to the cysteine-50 site is an essential to unfolding. Myohemerythrin (from Themiste zostericola) and the monomeric N-ethylmaleimide derivatives of methemerythrin from P. gouldii and T. zostericola, in contrast, react rapidly with SDS. The products from denaturing of all proteins appear similar, having reduced alpha-helix content, very small absorbance in the 350-500 nm region and loss of anion or oxygen binding capacity. They do, however, retain the two irons, which can readily be removed with desferrioxamine B.

Animals↗
PubMed1985

Reaction of hemerythrin with disulfides.

The reactions of hemerythrin from Phascolopsis gouldii with the specific sulfhydryl reagents 5,5'-dithiobis(2-nitrobenzoate), 2,2'-dithiodipyridine, and 4,4'-dithiodipyridine were studied at 25 degrees C. Spectrophotometric measurements showed that 1 mol of disulfide reacted per protein subunit consistent with a single cysteine at residue 50. Reaction leads to dissociation of the octameric structure of the native protein to monomers. The first-order rate constants at 25 degrees C and pH 9.0 for reactions of methemerythrin [(1.5 +/- 0.3) X 10(-3) s-1] and metazidohemerythrin [(4.0 +/- 0.3) X 10(-3) s-1] are independent of both the concentration and the nature of the disulfide. The reactions of methemerythrin are strongly inhibited by ClO4-ion, which however has no effect on the rates of those of metazidohemerythrin. The first-order kinetic behavior is ascribed to a conformational change involving the protein controlling the reaction, and this slow change appears to dominate a number of the reactions of hemerythrin.

2,2'-Dipyridyl↗
PubMed1985

Radial artery cannulation and ischaemic damage: a review.

A review of the literature concerning ischaemic complications following radial artery cannulation suggests that the Allen test has little predictive validity. Other methods of assessing the ulnar collateral circulation are discussed.

Adult↗