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Biomedical subjects

A M Davie

Publications and source records attributed to A M Davie.

6 recordsLinked to original sources
PubMed2005

Introduction to competition between continuous cultures of Phaeodactylum tricornutum and Dunaliella tertiolecta.

When the diatom, Phaeodactylum tricornutum, and the microalga, Dunaliella tertiolecta, are cultured together in a chemostat at dilution factors of approximately 0.5 day-1, the diatom develops the higher population density. At dilution factors above 1.2 day-1 the inability of the diatom to assimilate nutrient as fast as it flows into the chemostat results in the microalga generating the larger population. This change in population densities is accompanied by an increase in the chlorophyll content of the diatom and a decrease in the chlorophyll content of the microalga. Two species of phytoplankton can coexist when they compete for nutrient in a chemostat providing they do not otherwise interact. When the species do interact coexistence in a stable steady state is possible providing intraspecies interactions exceed the interactions between the species. Both species adjust their consumption to minimise the concentration of nutrient in the chemostat and their growth is modified to match the dilution factor of the flow.

Adaptation, Physiological↗
PubMed1979

The 'singles' method for segregation analysis under incomplete ascertainment.

Li & Mantel (1968) proposed a simple new method of segregation analysis under complete ascertainment. This paper shows that, with a slight modification, the method is also valid under incomplete ascertainment. The assumptions concerning ascertainment are discussed and the method compared with the maximum likelihood method and Weinberg's proband method.

Genetic Diseases, Inborn↗
PubMed1978

On effects of relaxed selection in familial disorders.

Theoretical predictions are made of the effect of improved treatments, with consequent increase in fertility of affected individuals, on the frequency of familial disorders. Multifactorial inheritance and some two-locus models are considered. (Changes for simple Mendelian disorders have been estimated previously by many authors.) It is estimated that, with two-locus or multifactorial models, an increase in frequency per generation of not more than a few per cent of the frequency of a disorder may be expected. The greatest increase will be in the first generation following introduction of the new treatment.

Gene Frequency↗
PubMed1976

International collaborative study of the spinal muscular atrophies. Part 1. Analysis of clinical and laboratory data.

There is considerable variation in age of onset, though in over three-quarters of cases onset is before 4 years of age. A febrile episode, often of viral origin, may be present at the time of onset and might possibly be of aetiological significance, perhaps by precipitating the disease in a genetically predisposed individual. Reduced fetal movements and floopiness at birth are present in about one third of those cases where the onset is in early childhood. It would seem that when the onset is before 4 years of age, and particularly if the child has never been able to sit without support, the prognosis is much worse than in cases where the onset is after the age of 4 years. The proximal limb muscles are predominantly affected and muscle tone is usually reduced but pseudohypertrophy is uncommon. Rarely are the cranial nerves affected. Muscle fasiculations are present in about half the cases. Almost 10% of cases appear to be mentally retarded. With regard to the EMG findings, spontaneous activity, reduced full effort pattern increased potential amplitude and duration and increased motor unit territory appear to be the most reliable diagnostic criteria. Routine histological evidence of neurogenic atrophy seems to be a more reliable diagnostic criterion than muscle histochemistry. However, this may be only reflect the way in which the data were selected, that is, from cases where a muscle biopsy showed evidence of neurogenic atrophy on routine histology. Finally the serum level of creatine kinase is rarely very high and in more than half the cases it is normal. The CSF chemistry is always normal.

Creatine Kinase↗
PubMed1976

International collaborative study of the spinal muscular atrophies. Part 2. Analysis of genetic data.

Most of the cases in the present study are of the juvenile onset, proximal form of spinal muscular atrophy. The results of the study indicate that the majority of these cases are due to one or more autosomal recessive genes, with very few being inherited as a dominant trait. Affected individuals very widely in the severity of the disease. When 2 or more sibs are affected, they tend to be similar as regards severity, but there are a substantial number of sibships in which this is not so. The data are consistent with either a single gene, with a wide range of expressivity due to the effects of other genes and/or environmental influences, or 2 or more genes, but with considerable overlap in their expression.

Adolescent↗