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Biomedical subjects

M B Smith

Publications and source records attributed to M B Smith.

At least 163 records · Page 9Linked to original sources
PubMed1982

Quantitative aspects of red cell size variation during pregnancy.

Red cell volume distribution curves may be readily obtained using electronic cell counters, and the proportion of cells that deviate from the normal population may be determined. In this study, we report the results of red cell volume distribution analyses in pregnant and non-pregnant females. The relationship between red cell volume distribution and other red cell indices is also studied. Statistical analysis showed good correlation between various Channelyzer parameters and red cell indices including Hb, RCC, MCV, MCH, and MCHC. A significant proportion of pregnant patients showed abnormal red cell volume distribution curves particularly in the latter half of pregnancy. During the latter half of pregnancy there was an increased proportion of microcytic cells in 8% of patients and evidence for macrocytosis was found in 67% of patients. In general there was good correlation between stages of gestation and Channelyzer parameters associated with macrocytosis. It is suggested that analysis of red cell size, which may be simply performed with minimal quantities of blood and inconvenience using the Channelyzer, could give insight into those conditions associated with variation in red cell size including iron deficiency and folate deficiency in pregnancy and it is conceivable that repeated estimations of these parameters could obviate the need for blanket administration of haematinics to the pregnant patient.

Adult↗
PubMed1981

Antenatal diagnosis of homozygous beta thalassaemia in Mediterraneans in Australia.

Facilities for the antenatal diagnosis of homozygous beta thalassaemia have recently become available in Australia and in this paper, data from a series of 18 pregnancies examined at The Royal Women's Hospital, Melbourne, are analysed. Fetal blood was collected by fetoscopy and adequate samples were obtained in 16 cases (89%). In 5 pregnancies, fetal blood was shown to have a marked reduction in beta globin production (beta/alpha synthesis less than 0.030) and these pregnancies were terminated. Two pregnancies (11%) were lost in the immediate post-fetoscopy period and in a third pregnancy, neonatal death followed premature labour at 26 weeks' gestation. Seven babies were delivered normally at 36-40 weeks' gestation and cord blood studies excluded homozygous thalassaemia in all cases. The remaining pregnancy has yet to be delivered.

Australia↗
PubMed1980

A 19F nuclear magnetic resonance study of the interaction between cytochrome c and cytochrome c peroxidase.

The reaction between ferrocytochrome c and yeast cytochrome c peroxidase was studied using cytochrome c derivatives specifically trifluoroacetylated at single lysine amino groups. The only modifications that decreased the reaction rate were those of lysines immediately surrounding the heme crevice, lysines 13, 25, 79, and 87. Modification of lysines 22, 55, 88, and 99 had no effect on the reaction. The 19F chemical shifts of the cytochrome c derivatives trifluoroacetylated at lysines 13, 79, and 87 were not changed upon complex formation with cytochrome c peroxidase, indicating that no detectable conformational changes occurred. The cytochrome c trifluoroacetyl groups had the same T1 values in the paramagnetic fluorocytochrome c peroxidase complex as in the diamagnetic reduced form of the complex, indicating that they were more than 2.3 nm from the paramagnetic iron atom in cytochrome c peroxidase. This is consistent with a separation of at least 1.5-2.0 nm between the iron atom of cytochrome c and the iron atom of cytochrome c peroxidase.

Animals↗
PubMed1980

Use of specific trifluoroacetylation of lysine residues in cytochrome c to study the reaction with cytochrome b5, cytochrome c1, and cytochrome oxidase.

The preparation, purification, and characterization of four new derivatives of cytochrome c trifluoroacetylated at lysines 72, 79, 87, and 88 are reported. The redox reaction rates of these derivatives with cytochrome b5, cytochrome c1 and cytochrome oxidase indicated that the interaction domain on cytochrome c for all three proteins involves the lysines immediately surrounding the heme crevice. Modification of lysines 72, 79, 87 had a large effect on the rate of all three reactions, while modification of lysine 88 had a very small effect. Even though lysines 87 and 88 are adjacent to one another, lysine 87 is at the top left of the heme crevice oriented towards the front of cytochrome c, while lysine 88 is oriented more towards the back. Since the interaction sites for cytochrome c1 and cytochrome oxidase are essentially identical, cytochrome c probably undergoes some type of rotational diffusion during electron transport.

Cytochrome c Group↗
PubMed1980

Electrode effectiveness during transcutaneous motor stimulation.

Four types of electrodes were evaluated for clinical effectiveness in electrically stimulating the quadriceps muscles to gain knee extension for time periods lasting up to 4 days. These electrodes included self-adhering pregelled pads, solvent-activated conductive tape, carbonized conductive silicone rubber, and felt-covered metal plates. The electrodes were compared for ability to produce knee extension torque, electrical impedance, ease of application, durability, comfort, and skin reactivity. Felt-pad electrodes soaked in tap water or saline produced the highest mean torque and lowest electrical impedance, which made them excellent choices for single session stimulation. Carbon-rubber electrodes with either gel produced slightly less torque, slightly higher impedances, and only minor skin reactions. They were relatively easy to apply, and the majority remained intact for the duration of the study period. They were found to be most suitable for prolonged functional electrical stimulation of the quadriceps. Stimulation using pregelled electrodes produced the lowest torque, and they displayed consistently higher electrical impedance. Even though they were easiest to apply and survived better than the other electrodes, they also produced the most skin reactions. The torque and electrical impedance of the activated-tape electrodes were extremely variable and unpredictable, and the process of application was long and involved, making them clinically impractical for either long or short stimulation.

Adult↗
PubMed1980

A survey of a clear triethanolamine hand soap in contact lens-wearing optometry students.

A survey was performed to determine the effectiveness of a clear triethanolamine soap in contact lens wearing optometry students. The soap appeared to leave little or no residue on fingers and as a result on lenses. The survey indicated that unscented clear triethanolamine soap is an excellent adjunct to the hand cleaning procedure of contact lens patients.

Contact Lenses↗
PubMed1979

Increased thermal stability of proteins in the presence of sugars and polyols.

Sugars and polyols stablize proteins against heat denaturation. Scanning calorimetry was used to obtain a quantitative estimate of the degree of stabilization. Solutions of ovalbumin, lysozyme, conalbumin, and alpha-chymotrypsinogen were heated at a constant rate, and the temperature of the maximum rate of denaturation was estimated (Tm). Addition of a sugar or polyol raised Tm. The magnitude of the stabilizing effect (delta Tm) depended on both the nature of the protein and the nature of the sugar or polyol, ranging from 18.5 degrees C for lysozyme at pH 3 in the presence of 50% (w/w) sorbitol to 0 degrees C for conalbumin at pH 7 in 50% glycerol solution. It is argued that this stablization is due to the effects of sugars and polyols on hydrophobic interactions. The strength of the hydrophobic interaction was measured in model systems in sucrose and glycerol solutions. Sucrose and glycerol strengthened the pairwise hydrophobic interaction between hydrophobic groups; however, they reduced the tendency for complete transfer of hydrophobic groups from an aqueous to a nonpolar environment. The extent of stabliziation by different sugars and polyols is explained by their different influences on the structure of water. The difference between the partial molar volume of the sugar or polyol and its van der Waals volume was used as a rough quantitative measure of the structure-making or structure-breaking effect. There was a linear relationship between this quantity and delta Tm.

Calorimetry, Differential Scanning↗
PubMed1979

Quantitative studies of Hb Bart's levels and red cell indices in alpha thalassaemia trait in Mediterraneans.

Haemoglobin Bart's was detected and quantitated in 42 babies during a survey of cord blood from neonates of Mediterranean origin. The distribution of Hb Bart's levels for the group appeared to be bi-modal, with modes at 2.0% and 5.5%. Haematological data obtained from 21 babies during the first week of life showed a highly significant reduction in average MCV (86.3 +/- 7.7 fl) and MCH (27.8 +/- 6.0 pg) in comparison with a control group of babies. However, there was no significant correlation between these parameters and Hb Bart's levels. Haematological data were available on 57 parents of the Hb Bart's babies and HbH preparations were positive in 28 cases (49%). Examination of red cell indices showed a highly significant reduction in the average MCV and MCH of parents with positive HbH preparations, and a diagnosis of alpha-thalassaemia (based on the presence of HbH inclusion bodies and reductions in MCV and/or MCH) was made in at least one parent in the majority of couples with both partners tested, suggesting that alpha-thalassaemia trait in people of Mediterranean origin is generally associated with detectable haematological changes.

Cyprus↗
PubMed1979

The influence of pilocarpine and atropine on pentobarbital-induced nystagmus in the New Zealand white rabbit.

Nystagmus, induced by intravenous pentobarbital in rabbits, increased in frequency and amplitude as a result of intravenous pilocarpine administration. In seven of nine animals anesthetized with pentobarbital but not showing eye movements, pilocarpine injection elicited nystagmus. In all rabbits, nystagmus was terminated by subsequent intravenous administration of atropine, indicating that the parasympathetic nervous system contributes to nystagmus observed in barbiturate treated animals. The results reported here are of value in their implication for an understanding of the physiologic mechanisms which underlie eye movement disorders commonly observed in barbituarate intoxicated individuals.

Anesthesia↗
PubMed1978

Incidence of alpha-thalassaemia in Australian population of Mediterranean origin.

Cord blood from 6578 neonates of Mediterranean origin born at The Royal Women's Hospital, Melbourne, over a five-year period was screened for alpha-thalassaemia by haemoglobin electrophoresis for haemoglobin Bart's (Hb Bart's), and 47 cases of the abnormal haemoglobin were detected (an over-all incidence of 0.71%). Hb Bart's was detected in Turks (2.9%), Cypriots (2.8%), Egyptians (2.0%), Lebanese (0.8%), Greeks (0.7%), Italians (0.5%), and Yugoslavs (0.2%). The mean level of Hb Bart's for the group was 4.6%. Four cases of alpha/beta thalassaemia were also detected during this survey.

Australia↗
PubMed1978

Effect of specific lysine modification on the reduction of cytochrome c by succinate-cytochrome c reductase.

The reduction of cytochrome c by succinate-cytochrome c reductase was studied at very low cytochrome c concentrations where the reaction between cytochrome c1 and cytochrome c was rate limiting. The rate constant for the reaction was found to be independent of ionic strength up to 0.1 M chloride, and to decrease rapidly at higher ionic strength, suggesting that the interaction between cytochrome c1 and cytochrome c was primarily electrostatic. The reaction rates of cytochrome c derivatives modified at single lysine residues to form trifluoroacetylated or trifluoromethylphenylcarbamylated cytochromes c were studied to determine the role of individual lysines in the reaction. None of the modifications affected the reaction at low ionic strength, but at higher ionic strength the reaction rate was substantially decreased by modification of those lysines surrounding the heme crevice, lysine-8, -13, -27, -72, and -79. Modification of lysine-22, -25, -55, -99, and -100 had no effect on the rate. These results indicate that the binding site on cytochrome c for cytochrome c1 overlaps considerably with that for cytochrome oxidase, suggesting that cytochrome c might undergo some type of rotational diffusion during the electron-transport process.

Animals↗
PubMed1978

Quantitation of globin chains using cellulose acetate electrophoresis: analysis of fetal globin chain production.

A technique involving the quantitative estimation of globin chains using cellulose acetate electrophoresis is described, and applied to the analysis of fetal globin chain production. When cord blood was analyzed, there was poor correlation between the globin chain ratios namely beta/alpha, gamma/alpha and beta/gamma ratios with either age or weight of newborn babies between 36-40 weeks gestation: best correlations were obtained for the beta/gamma ratio against weight (P less than 0.05). However, there was highly significant correlation between the various globin chain ratios and either age or weight of the newborn infant up to 12 weeks of age (P less than 0.001). This technique allows visual demonstration and quantitation of abnormal haemoglobins in a single procedure.

Aging↗