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Biomedical subjects

B Murray

Publications and source records attributed to B Murray.

At least 55 records · Page 3Linked to original sources
PubMed1995

Variation in N-linked carbohydrate chains in different batches of two chimeric monoclonal IgG1 antibodies produced by different murine SP2/0 transfectoma cell subclones.

Two chimeric human/murine monoclonal antibodies were constructed by substitution of the murine constant regions with human gamma 1 and kappa constant regions for heavy and light chains, respectively. The chimeric human/murine molecules are anti-idiotypic antibodies, meaning that they were directed against the antigen binding site in the variable region of another antibody. Antibody batches were produced under identical production conditions, using two selected SP2/0 myeloma cell subclones, which produce chimeric antibodies with different variable regions, but identical constant regions. Several samples were collected during the production of the antibodies in hollow-fibre reactors. The heavy chain, but not the light chain, of the two different chimeric IgG1 antibodies is glycosylated. Structural analysis of the enzymically released N-linked carbohydrate chains by 1H-NMR spectroscopy, as well as by chromatographic profiling, demonstrated that the collection of N-glycans comprises a small amount of monoantennary, and for the greater part diantennary structures. The N-glycans are completely (alpha 1-->6)-fucosylated at the innermost GlcNAc residue. The antennae of the neutral diantennary N-glycans are built up from GlcNAc beta 1-->2, Gal beta 1-->4GlcNAc beta 1-->2 or Gal alpha 1-->3G alpha 1 beta 1-->4GlcNAc beta 1-->2 elements, whereas the antennae of the neutral monoantennary carbohydrate chains have only (beta 1-->2)-linked GlcNAc residues. Galactosylation of the GlcNAc beta 1-->2Man alpha 1-->6 branch occurs four times more frequently than that of the GlcNAc beta 1-->2Man alpha 1-->3 branch, independently of the production batch. A small amount of the diantennary N-glycans are mono- or disialylated, carrying N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc), exclusively (alpha 2-->6)-linked to beta Gal. Analysis of the different production batches demonstrates that the structures of the N-linked carbohydrate chains are identical in the two chimeric antibodies, but that the relative amounts of the major oligosaccharide components, the degree of sialylation and the molar ratio of Neu5Ac to Neu5Gc varies with the SP2/0 cell subclone, and only slightly with cell age.

Animals↗
PubMed1995

Adaptation to high-fat diets: effects on eating behaviour and plasma cholecystokinin.

Twelve male subjects took part in a study to investigate the effects of overfeeding a high-fat diet (19.17 MJ/d; 58% energy from fat) for 2 weeks on plasma cholecystokinin (CCK) levels, food intake, and subjective feelings of hunger and fullness. Before and after the diet, subjects completed a 2-week weighed dietary inventory, formal measurements of food intake from a pre-selected appetizing evening meal were carried out, and blood samples were taken after a standard breakfast for measurement of CCK. Hunger and fullness were rated on visual analogue scales before and after each of these meals and at evening meals during the diet period. Following the high-fat diet there was a small non-significant increase in food intake from the pre-selected meal (6919 (SE 615) kJ v. 6405 (SE 540) kJ; P = 0.1) and a significant increase in the average daily food consumption measured from the diaries (10.25 (SE 0.49) MJ/d v. 9.59 (SE 0.62) MJ/d; P = 0.05). Corresponding trends of increasing feelings of hunger and declining fullness also occurred over the study period. Plasma CCK responses to the standard breakfast were raised following the diet (1285 (SE 153) v. 897 (SE 78) pM min; 3 h integrated CCK production post v. pre diet; P < 0.01) with the major differences observed at 90 and 120 min following the meal. These results suggest that the increase in food intake may be related to a down-regulation in putative CCK receptors responsible for food intake. Elevated CCK levels might suggest a corresponding down-regulation in CCK receptors responsible for feedback inhibition of CCK release.

Adaptation, Physiological↗
PubMed1995

Parametrization of head-scatter factors for rectangular photon fields using an equivalent square formalism.

Head-scatter factors of symmetric square and rectangular fields (field center on the central beam axis) defined by the upper (Y) and lower (X) jaws for 6 and 15 MV photon beams from 2300CD and 600C accelerators (Varian Associates, Inc., Palo Alto, CA) were measured, as well as those for fields shaped by the Y jaws and the multileaf collimator (MLC) of the 2300CD. For rectangular fields, the head-scatter factor for the field (x = a and y = b) was different from that for the field (y = a and x = b). This difference was 2% -3% for fields defined by conventional collimators when [formula, see text] was large, and became 4%-5% when the MLC and YT jaws were used to shape the fields with the X jaws retracted. In order to calculate values for head-scatter factors of rectangular fields accurately using an equivalent square formalism, the side of the equivalent square should be obtained with different weights for lower and upper jaws, as proposed by Vadash and Bjärngard [Med. Phys. 20, 733-734 (1993)]. Our measurements demonstrate that the relative weight (G) of upper and lower jaws is strongly dependent on their distances from the x-ray source, while the beam energy has little effect on the value of G. We further show that G can be calculated simply from these distances. An analytical representation for head-scatter factors of square and rectangular fields is also developed in this paper. The quality of this representation was judged by the root-mean-square (rms) deviation from measured head-scatter factors, which ranged from 0.11%-0.27%.

Head↗
PubMed1995

Safety and efficacy of increasing wintertime vitamin D and calcium intake by milk fortification.

We studied the safety and efficacy of milk fortified with vitamin D3 and calcium. Over the winter, we conducted a double-blind, placebo-controlled trial of fortified milk (12 micrograms vitamin D3 and 1525 mg calcium per litre) compared to unfortified milk (0.3 micrograms vitamin D3 and 1270 mg calcium per litre) in 102 adults (aged 17-54 years). Serum 25-hydroxyvitamin D [25(OH)D], ionized calcium, and creatinine were measured at baseline and after intervention. Fortification reduced the seasonal decline in serum 25(OH)D concentrations by > 50%. In the fortified group, serum 25(OH)D decreased by 15 nmol/l from 77 +/- 35 nmol/l to 62 +/- 26 nmol/l (p < 0.001). In the control group, serum 25(OH)D fell by 31 nmol/l from 85 +/- 38 nmol/l to 54 +/- 25 nmol/l (p < 0.001). We suggest that milk enriched with vitamin D be provided in high-latitude European countries to diminish the wintertime fall in serum 25(OH)D.

Adolescent↗
PubMed1994

Evidence implicating both slow- and fast-conducting fibers in the rewarding effect of medial forebrain bundle stimulation.

A behavioral version of the collision test was used to determine whether reward-relevant neurons directly link self-stimulation sites in the lateral hypothalamic (LH) and ventral tegmental (VTA) areas. Five male rats served as subjects. Trains of conditioning (C) and test (T) pulses were delivered to the two stimulation sites, each site receiving one of the pulses from each pair. The C-T interval was varied from 0.2-17.3 ms, and the effectiveness of the paired pulse stimulation was estimated by comparing the rate-number curve obtained at each C-T interval to rate-number curves obtained with trains of evenly spaced single pulses delivered via one electrode. For 4 of the subjects, stimulation effectiveness increased with the C-T interval, and the form of this increase was similar regardless of which electrode delivered the C-pulses. These increases in effectiveness are consistent with recovery from collision block in reward-relevant fibers stimulated at both sites. The domain of the rising portion of the effectiveness versus C-T interval curve spanned 2.2-7.7 ms. Such a gradual rise suggests that the directly stimulated substrate is composed of fibers with a wide range of conduction velocities and/or refractory periods. The discrepancy between these gradually rising collision curves and the steeply rising curves obtained in previous collision studies may have been due to inadequate sampling of the rate-number function in the earlier studies.

Animals↗
PubMed1994

(-)-Deprenyl alters the survival of adult murine facial motoneurons after axotomy: increases in vulnerable C57BL strain but decreases in motor neuron degeneration mutants.

The effect of (-)-deprenyl on the survival of axotomized adult murine facial motoneurons was investigated. Previously, (-)-deprenyl was shown to increase the number of rat facial motoneurons (FMns) surviving after axotomy at postnatal day 14, apparently by compensating for the loss of muscle-derived trophic factor. In the present study, three different strains of adult mice--A/J, C57BL/6J, and a congenic substrain of the C57BL/6J mice, the C57BL/Mnd mutants--underwent unilateral facial nerve transection. FMns were counted from serial sections taken through the entire length of the facial nuclei ipsilateral and contralateral to the facial nerve transections in animals sacrificed 21 days after axotomy. Subgroups of C57BL/6J and Mnd mutants were treated with either saline or 1.0 mg/kg (-)-deprenyl for 21 days. Another subgroup of Mnd mutants were treated with the metabolites of (-)-deprenyl, a mixture of (-)-amphetamine and (-)-methamphetamine, at a dosage equimolar to 1.0 mg/kg (-)-deprenyl. The number of surviving facial motoneurons in the A/J strain was 90% of unlesioned, control values which supports previous findings that adult FMns receive adequate trophic support and thus can survive loss of muscle-derived trophic support. In the C57BL/6J strain, the facial motoneuron survival was 35% and (-)-deprenyl increased the survival to 50.5%. Mnd mutants showed 62.4% survival; however, (-)-deprenyl decreased the number of motoneurons to 54.9% and amphetamine and methamphetamine treatment further decreased the motoneuron survival to 41.1%. These findings show that FMns in the Mnd mutants and their parental strain, C57BL/6J mice, show greater vulnerability to axotomy as compared to other adult strains of mice. The vulnerability is similar to that found in early postnatal life. (-)-Deprenyl increases the survival of the axotomized C57BL/6J FMns but its major metabolites, (-)-methamphetamine and (-)-amphetamine, further decrease FMn survival in the C57BL/Mnd mutants, possibly due to the induction of neurotoxic proteins causing programmed neuronal death. The efficacy of (-)-deprenyl in increasing the survival of damaged neurons would be expected to decrease as dosage increased above the dosage sufficient to induce maximum neuronal rescue (approximately 0.01 mg/kg) but would decrease as the dosage exceeded that necessary to produce toxic concentrations of the metabolites of (-)-deprenyl (1.0 mg/kg in this study).

Amphetamine↗
PubMed1994

Plasma P-selectin is increased in thrombotic consumptive platelet disorders.

P-selectin is a 140-kD protein found in the alpha-granules of platelets and the Weibel-Palade bodies of endothelial cells that on cell activation is expressed on the cell surface and also secreted into the plasma. The secreted form of P-selectin, like plasma P-selectin, differed from platelet membrane P-selectin in that its molecular mass was approximately 3 kD lower under reducing conditions. Both the secreted and plasma forms of P-selectin contained cytoplasmic sequence as determined by Western blot analysis with an affinity-purified rabbit anti-P-selectin cytoplasmic peptide antibody. We have measured plasma P-selectin and beta-thromboglobulin (beta TG) concurrently in (1) patients with consumptive thrombotic disorders, including disseminated intravascular coagulation (DIC), heparin-induced thrombocytopenia (HIT), and thrombotic thrombocytopenic purpura (TTP)/haemolytic uremic syndrome (HUS); (2) patients with idiopathic thrombocytopenic purpura (ITP); and (3) healthy controls. Patients with DIC, HIT, and TTP/HUS, but not ITP, had significantly elevated plasma P-selectin and beta TG levels when compared with their age-matched healthy controls. The increased plasma P-selectin and beta TG in patients with thrombotic disorders were likely to be the result of in vivo platelet and endothelial cell damage or activation. We also found that avoidance of veno-occlusion and other tedious measures customarily taken during blood collection and sample preparation to prevent in vitro platelet activation did not affect plasma P-selectin assay results. In addition, plasma P-selectin levels were not influenced by the presence of renal failure or heparin administration. These results indicate that plasma P-selectin may be a useful new marker for thrombotic diseases.

Adult↗
PubMed1993

The prevalence of microalbuminuria and associated risk factors in a population with insulin-dependent diabetes mellitus.

The prevalence of microalbuminuria was studied in a clinic population of patients with insulin-dependent diabetes mellitus [IDDM] with disease duration longer than 5 years. 75 patients were included in the study, 23 patients (30.7%) had microalbuminuria and 2 patients (2.7%) had macroalbuminuria. Comparison of the clinical and laboratory characteristics of patients with microalbuminuria (n = 23) to patients with normoalbuminuria (n = 50) showed no differences with respect to age, duration of diabetes, blood pressure, presence of retinopathy and glycosylated haemoglobin. The mean glomerular filtration rate (GFR) was higher in the microalbuminuric group than in the normoalbuminuric group (125 +/- 45 ml/min compared to 99 +/- 32 ml/min; P < 0.05). In a multiple regression model excluding patients with macroalbuminuria the following predictors of albumin excretion rate (AER) were identified: systolic blood pressure, glycosylated haemoglobin and GFR. Since microalbuminuria is common in Irish patients with IDDM, we suggest that AER should be determined as part of the annual routine screen. Stricter control of blood pressure and glycaemia should be considered.

Adult↗
PubMed1993

Is cholecystokinin a satiety hormone? Correlations of plasma cholecystokinin with hunger, satiety and gastric emptying in normal volunteers.

This study was designed to test the putative role of plasma cholecystokinin (CCK) in eating behaviour by examining the relationships between bioassayed plasma CCK concentrations and rated sensations of satiety and hunger following the ingestion of an appetizing nutrient-dense meal and between plasma profiles of CCK and scintigraphically determined gastric emptying in nine healthy male volunteers. Mean plasma CCK levels from the whole group showed a significant negative correlation with mean hunger ratings (r = -0.64) and a positive correlation with fullness (r = +0.68). However, there was considerable interindividual variation and negative correlations with hunger were only seen in three out of nine subjects and positive correlations with fullness in four out of nine subjects. In contrast, there was a strong relationship between the plasma CCK produced over the first 2 h after the meal and the half time for gastric emptying of the meal (r = -0.81). These data do not support a direct role for circulating levels of CCK in the control of hunger and satiety following a meal. Instead, the strong correlation with gastric emptying is compatible with release of CCK in response to nutrient delivery into the small intestine.

Cholecystokinin↗
PubMed1993

New home-delivered training prospects for people with disabilities.

The 'Home-Delivered Training Project' set out to test the viability of providing training in Information Technology to people with physical disabilities in their homes, using computers and modem links. The course included core modules on business applications software and optional modules on more specialist applications. The computer-based approach to instruction included computerized monitoring of student progress, the provision of on-line tutorial support as well as computerized test administration and marking. The 20 course participants, who lived in locations throughout Ireland, were unable to attend conventional training centres because of their limited mobility or other restrictions arising from their disabilities. They differed considerably in terms of disability type, educational qualifications and experience with computers. All but one of them completed the course successfully and were awarded certificates which are recognized in Ireland and the United Kingdom. Overall, they were very positive about the course, mainly because they could undertake it in their homes at a flexible pace to suit their learning patterns and the requirements of their disabilities. They recognized, however, that studying at home required a self-disciplined study routine which was not always easy to maintain. The fact that they were awarded an internationally recognized qualification on completion of the course was an important motivating factor, as it made the course relevant in terms of their employment aspirations.

Accreditation↗
PubMed1993

Preliminary studies on the gastrointestinal responses to fatty meals in obese people.

Studies were carried out on eight obese (BMI 30-34.6 kg/m2) and seven age and sex-matched normal weight volunteers (BMI 20-25 kg/m2) to investigate the gastric emptying, mouth to caecum transit time (MCTT), plasma cholecystokinin (CCK) and sensory responses to high (30 g margarine; 1327 kJ (317 kcal)) and low (301 kJ (72 kcal)) fat soups. Gastric emptying was measured by gamma scintigraphy, MCTT was measured by the breath hydrogen technique, plasma CCK was measured using a bioassay technique and subjective sensations were recorded on visual analogue scales. The high fat meal emptied more slowly than the low fat meal in both the normal subjects (t1/2 = 86.3 +/- 9.2 vs. 36.7 +/- 2.8 min) but there were no differences in the emptying of either meal between the two groups of subjects. Increasing the fat content of the meal did not affect the mouth to caecum transit time (MCTT) in either group, nor were there differences between the groups in MCTT (180 +/- 23 vs. 188 +/- 35 min, normal vs. obese MCTT after low fat soup; 228 +/- 17 vs. 227 +/- 29 min, normal vs. obese MCTT after high fat soup). Despite similar rates of gastric emptying, the obese group showed a higher CCK production following the high fat meal than the normal weight group (540.4 +/- 65.9 vs. 336.9 +/- 51.4 pmol.min, 2 h integrated CCK production, obese vs. normal; P < 0.05). The obese group also reported feeling less hungry throughout the study than the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Purification and biochemical characterization of non-myristoylated recombinant pp60c-src kinase.

To obtain sufficient material for the biochemical and biophysical study of pp60c-src, we have utilized a recombinant pp60c-src baculovirus lacking the myristoylation site at codon 2. On infection of Sf9 cells, this virus produced large amounts of soluble non-myristoylated pp60c-src. The use of non-myristoylated pp60c-src (1) increases production of pp60c-src compared with the wild-type protein, (2) facilitates purification, (3) yields a stable product and (4) allows biochemical studies in the absence of detergents. Up to 20 mg of pp60c-src of greater than 95% purity has been purified from 6 litres of Sf9 cells grown in a bioreactor. One major and multiple minor forms of pp60c-src were separated by Mono Q f.p.l.c. Isoelectric focusing of purified pp60c-src species revealed heterogeneity, some of which could be attributed to differences in the tyrosine phosphorylation state of the enzyme. Kinetic analysis of non-myristoylated pp60c-src kinase in the presence of Mg2+ gave Km values for angiotensin II and ATP of 2 mM and 30 microM respectively and a Vmax. of 620 nmol/min per mg. The kinetic constants and metal ion preferences of a number of copolymers and peptide substrates have been compared. Polylysine and poly(GLAT), which was not phosphorylated by the pp60c-src kinase, dramatically activated autophosphorylation of Tyr-416, suggesting a conformation modulation of pp60c-src by charged polymers. This finding implies that Tyr-527 dephosphorylation is not sufficient for full activation of pp60c-src in vitro.

Amino Acid Sequence↗
PubMed1992

Development of solid-phase enzyme-linked immunosorbent assays for the determination of epidermal growth factor receptor and pp60c-src tyrosine protein kinase activity.

Solid-phase ELISAs for the determination of EGF receptor (EGF-R) and pp60c-src tyrosine protein kinase activity are described. The methods were developed and optimized using purified recombinant EGF-R intracellular domain (ICD) and pp60c-src tyrosine protein kinases. A standardized assay that utilizes poly (GluNa-Tyr)4:1 as substrate and a monoclonal antiphosphotyrosine antibody for detection is described. Assay conditions for both enzymes were optimized with respect to substrate and ELISA plate-coating condition, divalent metal ion preferences, enzyme concentration, apparent kinetic constants for ATP, and reaction linearity. Following standardization, a number of reference tyrosine protein kinase inhibitors were tested in the ELISAs and compared to results obtained using solution-phase radioactive tyrosine protein kinase assays, which are based on the transfer of 32P from [gamma-32P]ATP to synthetic substrate. To enable a comprehensive comparison, IC50 values obtained in the ELISA were compared with values obtained in radioactive assays using both the holo-EGF-R and EGF-R ICD kinases. No substantial qualitative differences between these assays were seen. For many routine tyrosine protein kinase assays, semiquantitative or qualitative measurement of TPK activity is adequate. For such purposes, the ELISAs would be an attractive alternative to radioactive assays.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

An ELISA capture assay for the E7 transforming proteins of HPV16 and HPV18.

ELISA capture assays were established for the E7 transforming proteins of HPV16 and HPV18, based on a range of previously characterised polyclonal and monoclonal antibodies. No cross-reactivity was observed in the ELISAs between HPV18 E7 and HPV16 E7. Immunoreactive E7 protein (iE7) was measured in a series of HPV-transformed cell lines, and ranged from 0.6 to 17.7 ng iE7/mg cell protein. iE7 was labile at 22 degrees C (t1/2 = 37 min) but relatively more stable at 4 degrees C (t1/2 = 210 min). HPV16 E7 protein at concentrations from 0.10 to 0.69 ng iE7/mg cell protein was detected in 5 of 13 smears from women with abnormal cervical cytology. Assay of E7 protein may play a role in the detection of HPV-induced cervical lesions with malignant potential.

Animals↗
PubMed1992

Handedness in childhood autism shows a dissociation of skill and preference.

Hand preference and hand skill were assessed in 20 children with autism, 20 normal controls and 12 children with mental retardation. 90% of the normal controls and 92% of the children with mental retardation showed concordance for hand preference and hand skill (i.e. the preferred hand was also the more skillful), whereas only 50% of the children with autism showed concordance of preference and skill, the remaining 50% preferring to use the hand which was less skillful. Children with autism also showed a lesser degree of handedness and a lesser degree of consistency than the other groups, although this was unrelated to the discordance of skill and asymmetry. A developmental model of handedness is proposed in which the development of handedness as preference is ontogenetically prior to the development of handedness as skill asymmetry, such that in normal children the development of skill asymmetry occurs as a secondary consequence of the establishment of preference. The causal sequence is disrupted in autism, so that although preference is established, it does not subsequently result in concordant skill asymmetry.

Autistic Disorder↗