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Biomedical subjects

A Roberts

Publications and source records attributed to A Roberts.

At least 307 records · Page 17Linked to original sources
PubMed1982

A scanning electron microscope study of the development of a peripheral sensory neurite network.

The formation of the sensory neurite plexus on the basal lamina of trunk skin in Xenopus embryos has been examined using the scanning electron microscope. It is formed by Rohon-Beard and extramedullary neurons which provide the first sensory innervation of the skin. By observing the distribution of growth cones on the inside surface of the skin of embryos at different ages, the development of the plexus has been followed and related to the development of sensitivity to sensory stimulation. The general features of the plexus are illustrated using a photomontage taken at x 1100. Measurements on neurites from this, and of growth cone orientations demonstrate a general ventral growth pattern with some small regional variations. Interactions of neurites within the plexus are examined. Neurites meeting at shallow angles tend to fasciculate, while those meeting at close to 90 degrees tend to cross each other. Angles of incidence and separation of neurites show few angles less than 30 degrees, which suggests that active adjustments occur after a growth cone meets or leaves another neurite. The observations allow comparison of behaviour of growing neurites in vivo and in vitro. Our evidence suggests that adhesion between growth cones and neurites is stronger than that between growth cones and the basal lamina of the skin.

Animals↗
PubMed1982

The development of the peripheral trigeminal innervation in Xenopus embryos.

The development of the ophthalmic, maxillary and mandibular nerves has been followed in Xenopus laevis embryos from the first emergence of growth cones from the trigeminal ganglia until the establishment of functional innervation of the skin or cement gland. The course of each main nerve is highly predictable and follows pre-existing openings between blocks of other tissues. The development of the mandibulary nerve was observed most easily. Like that of the other trigeminal nerves it falls into three stages: (1) A pioneer neurite emerges and a nerve forms as other, later neurites fasciculate with this. (2) On reaching the inside surface of the cement gland the neurites separate and penetrate holes in the basal lamina. (3) The neurites grow between the cells they will innervate and form free nerve endings. The scanning EM observations have been confirmed by electrical recordings from trigeminal neurones. The role of pioneer fibres and substrate guidance are discussed.

Action Potentials↗
PubMed1981

Amniotic fluid cholinesterase measurement as a rapid method for the exclusion of fetal neural tube defects.

Amniotic fluid total cholinesterase (ChE) and acetylcholinesterase (AChE) activities have been measured in 404 pregnancies without fetal malformation and 79 pregnancies associated with open neural-tube defects (NTDs). Neither measurement, either alone or in combination, gave complete separation of the two groups. However, measurement of ChE can be used to assess the probability that a woman is carrying a fetus with an open NTD. Since ChE can be measured within 15 minutes and shows at least 70% of women selected for amniocentesis by serum alpha-fetoprotein screening to have a less than 1 in 100 chance of carrying a fetus with an open NTD, we suggest that this test may be used in an amniocentesis clinic both to reassure women with normal pregnancies and to select probable abnormalities for immediate further investigation.

Acetylcholinesterase↗
PubMed1981

Non-O group 1 Vibrio cholerae gastroenteritis associated with eating raw oysters.

A cluster of five cases of non-O group 1 (non-O1) V. cholerae gastroenteritis occurred in one Florida locality during November 1979. Clinical findings included nausea, vomiting, and abdominal cramping in all affected persons; two had bloody diarrhea. All five persons gave a history of eating raw oysters within four days of onset of illness. A case-control study statistically associated the eating of raw oysters with development of illness (p = 0.0008); this finding was confirmed by a retrospective cohort study of patients hospitalized for diarrhea (p = 0.0001). Non-O1 V. cholerae organisms were isolated from oysters and water samples taken from areas where ill persons had obtained their oysters. In at least one instance the same serotype was isolated from a patient's stool specimen and from the water where the patient had obtained oysters. Non-O1 V. cholerae infection must be considered in the differential diagnosis of shellfish-associated gastroenteritis.

Adult↗
PubMed1981

Whooping cough in nursery school children.

This paper describes an outbreak of whooping cough in a nursery school during a large epidemic in West Glamorgan. Explosive outbreaks of whooping cough occurred in nursery schools in the area when the majority of children had not been vaccinated. It is recommended that the period of quarantine for whooping cough should be four weeks.

Child↗