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Biomedical subjects

G Russell

Publications and source records attributed to G Russell.

At least 217 records · Page 12Linked to original sources
PubMed1976

The effect of several diphosphonates on acid phosphohydrolases and other lysosomal enzymes.

Diphosphonates are known to inhibit bone resorption in tissue culture and in experimental animals. This effect may be due to their ability to inhibit the dissolution of hydroxyapatite crystals, but other mechanisms may be important. Since lysosomal enzymes have implicated in the process of bone resorption, we have examined the effect of several phosphonates and of a polyphosphate (P20,2) on lysosomal hydrolases derived from rat liver and rat bone. Dichloromethylene diphosphonate strongly inhibited acid beta-glycerophosphatase (EC 3.1.3.2) and acid p-nitrophenyl phosphatase (EC 3.1.3.2) and to a lesser degree (in descending order) acid pyrophosphatase (EC 3.1.3.-), arylsulfatase A (EC 3.1.6.1), deoxyribonuclease II(EC 3.1.4.6) and phosphoprotein phosphatase (EC 3.1.3.16) of rat liver. Inhibition of acid p-nitrophenyl phosphatase and arylsulfatase A was competitive. Ethane-1-hydroxy-1, 1-diphosphonate did not inhibit any of these enzymes, except at high concentrations. Neither dichloromethylene diphosphonate nor ethane-1-hydroxy-1, 1-diphosphonate had any effect on beta-glucuronidase (EC 3.2.1.31), arylesterase (EC 3.1.1.2) and cathepsin D (EC 3.4.23.5). Of several other phosphonates tested only undec-10-ene-1-hydroxy-1, 1-diphosphonic acid inhibited acid p-nitrophenyl phosphatase strongly, the polyphosphate (P20, I) had little effect. Acid p-nitrophenyl phosphatase in rat calvaria extract behaved in the same way as the liver enzyme and was also strongly inhibited by dichloromethylene diphosphonate, but not by ethane-1-hydroxy-1, 1-diphosphonate. It is suggested that the inhibition of bone resorption by dichloromethylene diphosphonate might be due in part to a direct effect of this diphosphonate on lysosomal hydrolases.

Acid Phosphatase↗
PubMed1976

Selection of skin tests in childhood asthma.

Skin tests have been applied to 161 asthmatic children seen consecutively at a paediatric respiratory clinic. To demonstrate whether a child's asthma is associated with a positive skin test it is suggested that only four extracts need be applied: house dust, house dust mite (D. farinae), grass pollens and a control.

Allergens↗
PubMed1976

Effective pulmonary capillary blood flow in infants with birth asphyxia.

Effective pulmonary capillary blood flow was measured on the first day of life in twenty term infants with birth asphyxia and twenty-five normal term infants. The infants studied showed no clinical or laboratory evidence of respiratory distress. The mean effective pulmonary capillary blood flow of 121 ml/kg/min in the birth asphyxia group was significantly lower than the mean of 162 ml/kg/min in the normal group. The possible relationship of birth asphyxia and pulmonary hypoperfusion in the aetiology of the idiopathic respiratory distress syndrome is discussed.

Asphyxia Neonatorum↗
PubMed1976

Practice effects for auditory localization: a test of a differentiation theory of perceptual learning and development.

Practice and transfer of practice in an auditory localization task were observed for three different information conditions (normal, transformed and reduced) to examine four aspects of Gibson's (1969) differentiation theory of perceptual learning and development. Support was found for the propositions that: (i) dimensions of difference, rather than prototypes, are learned; (ii) specificity is a more appropriate response measure than number of correct responses; (iii) perceptual learning will occur regardless of whether feedback is given or not; (iv) transfer of practice will be greater if dimensions of difference (as opposed to prototypes) are learned. It was also found that feedback during practice did not affect transfer. In an apparent contradiction though, specificity increased in the absence of dimension of difference. This increase was interpreted as being associated with the detection of non-task-related information and was seen as lending support to Gibson's hypothesis that, perceptual learning is motivated by intrinsic cognitive drive and is terminated by a reduction in subjective uncertainty.

Auditory Perception↗
PubMed1976

Effective pulmonary blood flow in preterm and light-for-date infants.

Using a method employing low concentrations (3%) of nitrous oxide, we measured effective pulmonary capillary blood flow (Qpc eff) in 23 preterm infants, 26 light-for-date infants, and 15 infants who were both preterm and light-for-date. All infants studied had no clinical or laboratory evidence of idiopathic respiratory distress syndrome (IRDS) and were studied before the age of 48 hours. The mean Qpc eff of 175 ml/kg/min in preterm infants (a group at high risk of developing IRDS), although significantly less than the mean of 214 ml/kg/min found in light-for-date infants (a group with a low risk of developing IRDS), was similar to that reported in normal term infants. The mean result for preterm, light-for-date infants was 189 ml/kg/min. No evidence was found that preterm infants were predisposed to IRDS as a consequence of preexisting pulmonary hypoperfusion.

Birth Weight↗
PubMed1976

Head position training with the cerebral palsied child: an application of biofeedback techniques.

A biofeedback training system has been developed for providing the cerebral palsied child with precise auditory and visual information regarding the spatial position of his head. The child actively practices correcting his head position by using feedback delivered through a mercury-switch device called a head position trainer. Twelve children have received clinical training and results are discussed in terms of feedback-sensitive, feedback-trained and feedback-learned, the results of treatment dictating the classification. It is concluded that the head position trainer is an effective sensory aid for the cerebral palsied child in the development of head control and position awareness. It is proposed that this system has excellent potential use as an adjunct to regular therapy programming in that it provides additional daily practice time and an objective method of recording the child's progress.

Cerebral Palsy↗
PubMed1975

Palmitic acid concentrations and lecithin/sphingomyelin ratios in amniotic fluid.

Palmitic acid concentrations and L/S ratios have been estimated in amniotic fluid specimens with and without centrifugation and cold acetone precipitation. Although the number of cases was small, both of these measurements in uncentrifuged fluid seemed to reflect only indirectly on lung maturation in normal pregnancy while with centrifuged fluid the L/S value predicted RDS in one infant more reliably than palmitic acid concentration.

Acetone↗
PubMed1975

Prenatal diagnosis and family studies in a case of propionicacidaemia.

In a family with a history of two neonatal deaths, propionicacidaemia was diagnosed retrospectively from stored plasma as the cause of the second death during the mother's next pregnancy. Amniocentesis was performed and a culture of amniotic cells was assayed for propionyl CoA carboxylase activity. The absence of any detectable propionyl CoA carboxylase activity allowed the prenatal diagnosis of propionicacidaemia to be made. Treatment with biotin and a modified aminoacid diet was started in the immediate postnatal period. Investigation of propionyl CoA carboxylase in leucocytes from the parents, siblings and other relations of the patient failed to demonstrate intermediate enzyme activities in even the parents, who were presumably heterozygotes for this condition.

Amino Acid Metabolism, Inborn Errors↗