PubMed Health⌕ Search

Biomedical subjects

T Robinson

Publications and source records attributed to T Robinson.

At least 19 recordsLinked to original sources
PubMed1992

Factor VIIa/tissue factor-catalyzed activation of factors IX and X on a cell surface and in suspension: a kinetic study.

The kinetics of activation of factor IX and factor X by factor VIIa was studied in the presence of various sources of tissue factor: (1) a surface membrane of human ovarian carcinoma cell line, OC-2008 (2) the cell lysate (of OC-2008) and (3) reconstituted purified human tissue factor. The rates of activation of factors IX and X were monitored in activation peptide release assays using tritiated substrates. The results indicate that the apparent Km values for factor IX and factor X were similar for a given tissue factor, but varied with tissue factor source. The source of tissue factor greatly influenced the apparent differences in Vmax for factors IX and X. When a surface of monolayer provided tissue factor, the Vmax of factor IX was only 2-3 fold lower than factor X, but when either a cell lysate or purified tissue factor was the source of cofactor activity, the difference in Vmax rose to about 8-10 fold. Although, the tissue factor apoprotein in the cells was expressed entirely on the outer surface membrane, the activity of tissue factor on the intact cell surface was 50 to 100-fold lower than in the lysed cell preparation.

Catalysis↗
PubMed1992

Dynamic and steady-state ventilatory and gas exchange responses to arm exercise.

Previous studies have suggested that, for the same power output, arm exercise requires higher oxygen uptake (VO2), carbon dioxide output (VCO2), and ventilation (VE) than leg exercise and that response kinetics are slower. To evaluate these differences, four healthy subjects performed a total of 95 arm cranking tests. Each subject performed several tests at each of three or four power outputs spaced evenly below the maximum the subject could sustain (average = 53 W). Breath-by-breath responses to identical stimuli were averaged. End-exercise blood lactate was determined at each power output. Responses were compared to leg exercise responses in these subjects (J. Appl. Physiol. 67:547-555, 1989). For power outputs unassociated with lactic acidosis, differences between steady-state VO2, VCO2, and VE responses for arm and leg exercise were not significant. At higher power outputs, the higher VO2, VCO2, and VE during arm exercise were well correlated with higher lactate. For power outputs not engendering lactic acidosis, the time constants (tau) for VO2, VCO2 and VE were not greatly different for arm than for leg exercise. For each variable, at higher power outputs tau became longer by an amount correlated with higher lactate level. Like leg exercise, the slower kinetics of VO2 and VE (but not VCO2) at higher power outputs were well described as a superimposed slower component. We conclude that both dynamic and steady-state responses of VE and gas exchange to arm exercise do not differ substantially from those to leg exercise so long as the power output does not elevate blood lactate.

Adult↗
PubMed1991

The formation of 3 alpha- and 3 beta-acetoxytropanes by Datura stramonium transformed root cultures involves two acetyl-CoA-dependent acyltransferases.

Tropine (tropan-3 alpha-ol) is an intermediate in the formation of hyoscyamine. An acyltransferase activity that can acetylate tropine using acetylcoenzyme A as cosubstrate has been found in transformed root cultures of Datura stramonium. A further acyltransferase activity that acetylates pseudotropine (tropan-3 beta-ol) with acetyl-coenzyme A is also present. These two activities can be partially resolved by anion-exchange chromatography, some fractions containing only the pseudotropine-utilizing activity. The basic properties of these two enzymes are reported and their roles in forming the observed alkaloid spectrum of D. stramonium roots discussed.

Acetyltransferases↗
PubMed1989

Totally implantable venous access systems in paediatric practice.

Forty seven totally implantable venous access systems have been inserted in 45 patients for the management of malignant disease (n = 29), haematological disorders (n = 5), and cystic fibrosis (n = 11). We report our experience with them and discuss the problems we have encountered during the past three years.

Adolescent↗
PubMed1989

Influence of work rate on ventilatory and gas exchange kinetics.

A linear system has the property that the kinetics of response do not depend on the stimulus amplitude. We sought to determine whether the responses of O2 uptake (VO2), CO2 output (VCO2), and ventilation (VE) in the transition between loadless pedaling and higher work rates are linear in this respect. Four healthy subjects performed a total of 158 cycle ergometer tests in which 10 min of exercise followed unloaded pedaling. Each subject performed three to nine tests at each of seven work rates, spaced evenly below the maximum the subject could sustain. VO2, VCO2, and VE were measured breath by breath, and studies at the same work rate were time aligned and averaged. Computerized nonlinear regression techniques were used to fit a single exponential and two more complex expressions to each response time course. End-exercise blood lactate was determined at each work rate. Both VE and VO2 kinetics were markedly slower at work rates associated with sustained blood lactate elevations. A tendency was also detected for VO2 (but not VE) kinetics to be slower as work rate increased for exercise intensities not associated with lactic acidosis (P less than 0.01). VO2 kinetics at high work rates were well characterized by the addition of a slower exponential component to the faster component, which was seen at lower work rates. In contrast, VCO2 kinetics did not slow at the higher exercise intensities; this may be the result of the coincident influence of several sources of CO2 related to lactic acidosis. These findings provide guidance for interpretation of ventilatory and gas exchange kinetics.

Adult↗
PubMed1988

Home intravenous antibiotic treatment in cystic fibrosis.

The prognosis for patients with cystic fibrosis who are colonised with Pseudomonas aeruginosa has improved as a result of the regular use of intravenous antibiotics; however, this necessitates long periods of hospitalisation. Home intravenous antibiotic treatment has potential advantages over hospital treatment. We describe our experience during the first 20 months of using a system of home intravenous antibiotic treatment in which a cystic fibrosis liaison sister has an essential role. Thirteen patients have received 40 courses of treatment. There were highly significant improvements in weight, respiratory function, and white cell count during home treatment. There was no significant difference in weight and forced expiratory volume in one second between the end of home treatment and the end of hospital treatment while forced vital capacity was better after home treatment. All patients preferred home treatment. The advantages of home visits by the cystic fibrosis liaison sister during treatment are emphasised.

Adolescent↗
PubMed1987

Comparison of four pancreatic extracts in cystic fibrosis.

Four different pancreatin products, Pancrease, Creon, Pancrex V Forte, and Pancreatin Merck, were compared in a random crossover trial in children with cystic fibrosis. The results of our study showed that patients who received Creon and Pancrease had fewer gastrointestinal symptoms than patients who received Pancrex V Forte and Pancreatin Merck. Fat absorption was significantly improved with Pancrease when compared with Pancrex V forte and Pancreatin Merck. Also the fat absorption with Creon was superior to that with Pancrex V Forte. There was no significant difference in fat absorption between Pancrease and Creon. Pancrex V Forte and Pancreatin Merck, or Pancreatin Merck and Creon. Faecal nitrogen content was less with both Creon and Pancrease compared with Pancreatin Merck. Creon and Pancrease allow the patient with cystic fibrosis to take a high energy diet without any dietary restrictions.

Adolescent↗
PubMed1986

Role of the supraoptic decussation in the development of asymmetry of brain function in the chicken.

The supraoptic decussation plays an important role in the development of asymmetry of brain function for visual discrimination learning in the chicken. Lesioning the decussation on day 2 has no effect on the asymmetry normally revealed by unilaterally treating either the left or right forebrain hemisphere with cycloheximide on day 4 of life. However, the lesion removes the asymmetry revealed by cycloheximide treatment on day 8 and reverses that revealed by treatment on day 10, albeit to a lesser extent. The asymmetry of learning performance between the left and right eyes present in untreated chickens tested monocularly in the second week of life is also removed by lesioning the supraoptic decussation. Thus, in the first week of life functional asymmetry is present but not dependent on left-to-right side coupling via the supraoptic decussation. The difference between lesioning during the first and second week of life may relate to the relative degree of maturation in the supraoptic decussation.

Age Factors↗
PubMed1986

A therapeutic feeding programme. I: Theory and practice of feeding.

Feeding problems are often commented on in the literature, but very little has been reported on the systematic examination of these problems. In the present study feeding disturbances were treated as part of a full diagnostic and treatment programme for disturbed children in a small residential psychiatric unit. The feeding programme was based on the early work of Clancy and colleagues in Australia, and consisted of offering the child food in a set situation by the same 'feeder'. A one-way screen was used for observation and video-recording. Three children are described in detail, and a striking effect was the immediacy of change in their feeding disturbances. It is stressed that early feeding difficulties of disturbed children can give rise or contribute to ever-widening faulty development.

Autistic Disorder↗
PubMed1986

A therapeutic feeding programme. II: Links with language and learning.

The feeding programme described in Part I of this study produced immediate change in the eating patterns of disturbed children, who then became available for learning and language development in a way they had not been previously. The authors give a broad outline of the principles and practice of functional learning, and the educational technique they used. They describe the language development of one child in detail, and the methods used. Follow-up details are also given for the three children described in Part I of the study.

Adolescent↗
PubMed1986

gamma-Aminobutyric acid receptor complex of insect CNS: characterization of a benzodiazepine binding site.

The specific binding of [N-methyl-3H]flunitrazepam ([3H]FNZP) to a membrane fraction from the supraoesophageal ganglion of the locust (Schistocerca gregaria) has been measured. The ligand binds reversibly with a KD of 47 nM. The binding is Ca2+-dependent, a property not found for the equivalent binding site in vertebrate brain. The pharmacological characteristics of the locust binding site show similarities to both central and peripheral benzodiazepine receptors in mammals. Thus binding is enhanced by gamma-aminobutyric acid (GABA), a feature of mammalian central receptors, whereas the ligand Ro 5-4864 was more effective in displacing [3H]FNZP than was clonazepam, which is the pattern seen in mammalian peripheral receptors. The locust benzodiazepine binding site was photoaffinity-labelled by [3H]FNZP, and two major proteins of Mr 45K and 59K were specifically labelled. In parallel experiments with rat brain membranes a single major protein of Mr 49K was labelled, a finding in keeping with many reports in the literature. We suggest that the FNZP binding site described here is part of the GABA receptor complex of locust ganglia. The insect receptor appears to have the same general organization as its mammalian counterpart but differs significantly in its detailed properties.

Affinity Labels↗