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Biomedical subjects

A P Norman

Publications and source records attributed to A P Norman.

At least 19 recordsLinked to original sources
PubMed1997

Excitatory interactions between antagonistic motor neurones underlying locust kicking and jumping during maturation after the adult moult.

There is a change in the synaptic connections between motor neurones that underlie locust kicking and jumping during maturation following the adult moult. The fast extensor tibiae (FETi) motor neurone makes monosynaptic excitatory connections with flexor tibiae motor neurones that have previously been implicated in maintaining flexor activity during the co-contraction phase of jumping, in which energy generated by the muscles of a hind leg is stored. The amplitude of the FETi spike decreases when repetitively activated, and this decrement is larger in locusts immediately following the adult moult than in mature locusts. The decrement in the FETi spike is correlated with a greater decrease in the amplitude of the flexor excitatory postsynaptic potential (EPSP) in newly moulted locusts and in turn with the failure of these locusts to kick or jump. The results presented here indicate that the developmental change in the connections between the motor neurones contributes to the change in behaviour following the moult.

Animals↗
PubMed1996

Proprioceptive feedback in locust kicking and jumping during maturation.

Campaniform sensilla monitor the forces generated by the leg muscles during the co-contraction phase of locust (Schistocerca gregaria) kicking and jumping and re-excite the fast extensor (FETi) and flexor tibiae motor neurones, which innervate the leg muscles. Sensory signals from a campaniform sensillum on the proximal tibia were compared in newly moulted locusts, which do not kick and jump, and mature locusts which readily kick and jump. The activity pattern of FETi during co-contraction was mimicked by stimulating the extensor tibiae muscle. Less force was generated and the spike frequency of the sensory neurone from the sensillum was significantly lower in newly moulted compared to mature locusts. Depolarisation of both FETi and flexor motor neurones as a result of sensory feedback was consequently less in newly moulted than in mature locusts. The difference in the depolarisation was greater than the decrease in the afferent spike frequency suggesting that the central connections of the afferents are modulated. The depolarisation could generate spikes in FETi and maintain flexor spikes in mature but not in newly moulted locusts. This indicates that feedback from the anterior campaniform sensillum comprises a significant component of the drive to both FETi and flexor activity during co-contraction in mature animals and that the changes in this feedback contribute to the developmental change in behaviour.

Aging↗
PubMed1993

Cathepsin D levels in primary breast cancers: relationship with epidermal growth factor receptor, oestrogen receptor and axillary nodal status.

Cathepsin D and the epidermal growth factor receptor (EGFr) have both been proposed as poor prognostic markers in breast cancer. We have compared the tumour cytosolic cathepsin D level with EGFr and oestrogen receptor (ER) levels and the axillary node status of 131 patients with operable breast cancer, to see if EGFr and cathepsin D are co-regulated. Cathepsin D level was measured using a two-site immunoradiometric assay kit. No correlation was found between the level of cathepsin D and EGFr, ER or nodal status. Since the raised level of cytosolic cathepsin D was not related to EGFr, it may be that measuring the level of both of these markers in the same sample will give additional prognostic information.

Biomarkers, Tumor↗
PubMed1980

Proteus vulgaris agglutination by cystic fibrosis sera.

The factor in sera of patients with cystic fibrosis (CF) and their parents which agglutinates Proteus vulgaris has characteristics similar to those of IgG antibody to this organism. Sera of patients without CF who have P. vulgaris infections agglutinate the organism similarly. At present there are too many false-positives in a control population for the test to be widely useful for heterozygote identification.

Adult↗
PubMed1979

Intestinal bile salts in cystic fibrosis: studies in the patient and experimental animal.

The quantitative and qualitative distribution of bile salts in the duodenal juice of 13 patients with cystic fibrosis (CF) was studied after a test meal. The effects of triolein (TO), bovine serum albumin (BSA), and ricinoleic acid (RA) on the absorption of taurocholate (TCA) in the distal ileum of the rat in vivo was also studied. The mean (and ranges) of total bile salt concentrations, glycine: taurine conjugate ratios, and percentage of dihydroxy bile salts in the patients with CF and pancreatic insufficiency were 3.5 (1.3--6.6) mmol/l, 8.6 (greater than 10-3.1), and 37 (10--60) compared with control values of 7.4 (3.0--16.0) mmol/l, 3.0 (1.3--4.5), and 61 (52--70) respectively. The differences between the control and CF values were statistically significant (P less than 0.01--P less than 0.001). Three of the 13 CF patients had total bile salt concentrations less than 2 mmol/l, 8 had much higher glycine: taurine ratios, and 8 had a reduced percentage of dihydroxy bile salts. In 2 patients with normal pancreatic enzyme activities, duodenal bile salts were both quantitatively and qualitatively normal. TO (10 and 30 mmol/l), BSA (3%), and RA (5 mmol/l) had no inhibitory effect on the ileal absorption of TCA. These results show pronounced abnormalities of duodenal juice bile salts in CF with pancreatic insufficiency consistent with a broken enterohepatic circulation (EHC); such abnormalities may contribute to defective lipid absorption in CF. The data in the experimental animal do not support the suggestion that unhydrolysed dietary substrates play a role in the pathophysiology of the broken EHC.

Adolescent↗
PubMed1977

Prevention of eczema.

In a prospective study of the development of reaginic allergy, infants of allergic parents were either subjected to an allergen-avoidance regimen from birth for six months or managed conventionally. The group on the allergen-avoidance regimen had less eczema at six months and one year than did the control group at six months. They also had a lower mean serum-total-IgE level at six weeks.

Allergens↗
PubMed1977

The relationship between chest radiographic scores and respiratory function tests in children with cystic fibrosis.

Chest radiographic scores and respiratory function on 80 sets of results from 50 patients with Cystic Fibrosis were analyzed. Chest radiographic scores were assessed independently using the method of Chrispin and Norman. Respiratory function tests were found to correlate well with the chest radiographic score, the best correlation being with the forced expiratory volume in 0.75 sec. to forced vital capacity ratio F.E.V. 0.75/ F.V.C. (r = -0.674 n = 80 p less than 0.001).

Adolescent↗
PubMed1976

Cystic fibrosis.

Explore the source record for details and available documents.

Adolescent↗
PubMed1976

Follow-up study of small-for-dates babies.

A group of small-for-dates full-term babies whose intra-uterine growth was followed by serial ultrasonic cephalometry were examined at a mean age of 4 years. Those children whose skull growth had begun to slow in utero before 34 weeks' menstrual age were more likely to have a height and weight less than the 10th centile. When the onset of growth failure had occurred before 26 weeks there was a lower developmental quotient at follow-up using the Griffiths extended scales. Prolonged slow growth in utero therefore seems to be followed by slow growth and development after birth.

Birth Weight↗
PubMed1976

Cystic fibrosis heterozygosity in the pathogenesis of allergy.

47% of cystic fibrosis (C.F.) heterozygotes had positive prick skin tests of 1 or more of 9 antigens and 53% had histories of allergic disease, both occurring significantly more often than in a control group. Since 1 in 20 of the population are C.F. carriers, this would contribute to allergy in the community.

Allergens↗
PubMed1976

Predisposing factors and the development of reaginic allergy in infancy.

In a prospective study of fifty-eight newborn infants of parents with reaginic allergy, twenty-seven developed eczema and twenty-eight positive prick tests to one or more of six antigens during the first year of life. These reaginic manifestations were related to presymptomatic transient IgA deficiency. The development of positive skin tests was also related to HLA A1 B8, and to season of birth. The order of frequency of positivity was Dermatophagoides, grass pollens, cat fur, feathers and cow's milk. The skin tests were often positive in infants in whom serum IgE was not detected. The eczema disappeared and the skin tests became negative in some infants at the end of the first year. This work suggests that sensitization in the new-born period is important in the subsequent development of disease.

Antibodies↗