Search PubMed⌕ Search

Biomedical subjects

J F Morris

Publications and source records attributed to J F Morris.

At least 181 records · Page 10Linked to original sources
PubMed1977

The effect of fixation conditions on the ultrastructural appearance of gastrin cell granules in the rat gastric pyloric antrum.

The ultrastructural appearance of gastrin cell (G cell) granules was studied after different fixation procedures. When the pH of prefixation was varied there was greater preservation of the electron density of granule cores after acidic (pH 5.0 and 6.0) than after neutral or alkaline (pH 7.0 and 8.0) prefixation. Increasing duration of prefixation at pH 7.3 resulted in progressive loss of electron density of the granule core with swelling and occasional rupture of the limiting membrane. In tissues where most granules had been rendered electron lucent by fixation, those granules remaining dense cored were preferentially located close to the Golgi zone. These findings indicate that the electron density of G cell granules is profoundly affected by conditions of fixation, and that immature granules are more resistant to loss of core density than mature granules. They also suggest that the gastrin granule in vivo, like other polypeptide granules, may have a "solid", osmotically inactive core.

Animals↗
PubMed1976

Assay of plasma 25-hydroxy vitamin D.

A radio-competitive protein-binding assay for 25-hydroxy vitamin D3 (25-OHD3) is described using diluted plasma from patients with vitamin D deficient osteomalacia as the binding protein. The 25-OHD3 is extracted from plasma with ethanol and assayed directly without further purification. An incubation of two hours is used to give suitable binding. The lower detection limit of the assay is approximately 23 pg, the intra-assay coefficient of variation is 5.4% and the inter-assay variation 15%. Tth a mean of 26.9 mug/l. Levels of plasma 25-OHD3 are undetectable in patients with vitamin D deficient osteomalacia and greater than 110 mug/l in patients taking large doses of vitamin D2.

Binding, Competitive↗
PubMed1976

Clinical comparison of two electronic spirometers with a water-sealed spirometer.

Two electronic spirometers which use a hot-wire anemometer to measure air flow were clinically compared with a water-sealed spirometer. The forced vital capacity (FVC), the forced expiratory volume in one second (FEV1), the FEV1/FVC%, the mean forced expiratory flow between 200 and 1,200 ml of the FVC, the mean forced expiratory flow during the middle half of the FVC, the mean forced expiratory flow between 75 and 85 percent of the FVC, and the maximum voluntary ventilation were determined for a group of 67 subjects. Techniques are described for connecting the spirometers in series to permit evaluation by human subjects or by syringe injection. High correlation coefficients generally were obtained when comparing the electronic spirometers with the water-sealed spirometer, but the actual range of percent difference was greater than 11 percent in all spirometric tests. The results indicate the need for systematic evaluation of electronic spirometers to characterize their deviation from accented standards. Frequent calibration is necessary to maintain consistent performance.

Adolescent↗
PubMed1976

Hormone storage in individual neurosecretory granules of the pituitary gland: A quantitative ultrastructural approach to hormone storage in the neural lobe.

A quantitative ultrastructural study of the neurosecretory granules in the neural lobe of the rat was performed in order to calculate the number of such granules in the neural lobe and thus, provided all hormone is intragranular, to derive the hormone content of individual granules. The results suggest that the gland contains 1 - 44 X 10(10) granules and that an individual granule (mean diameter 160 nm) contains about 84000 hormone molecules. The errors involved in the many measurements made are analysed, and the calculated value for the amount of space available for each hormone molecule within the granule is shown to agree well with independently reported data for the expected size of a molecule of protein-hormone complex, and for the size of subunits visualized in freeze-etched material. These results are compatible with exclusive intragranular hormone storage as a 'solid' core, and the physical form that this core might take is discussed. The data are used to express what is known of hormone turnover and release in terms of the numbers of granules involved. Comparison of different parts of the neural lobe suggests that, apart from the most anterior part of the gland, there is little regional variation in quantitative aspects of granule storage in the neural lobe.

Animals↗
PubMed1976

Distribution of neurosecretory granules among the anatomical compartments of the neurosecretory processes of the pituitary gland: a quantitative ultrastructural approach to hormone storage in the neural lobe.

The distribution of neurosecretory granules in various anatomical compartments of neurosecretory axons of the neural lobe of the rat pituitary has been studied. Apart from the most anterior tip of the gland, where granules are largely restricted to undilated axons and a few 'swellings', the proportional compartmental storage of granules is essentially homogeneous for the rest of the gland: 13% of granules are found in undilated axons, 31% in axonal 'endings' (which contain microvesicles and abut the basement membrane) and 55% in axonal 'swellings' (which are devoid of significant numbers of microvesicles). These values indicate that the 'endings' contain a much greater proportion of the total number of granules stored in the neural lobe than would be predicted if the readily releasable pool of hormone were composed of all the granules in the 'endings'. Some further constraint on granule release either physiological or anatomical (e.g. the position of the granule in relation to the plasmalemma of the 'ending') must be operative.

Animals↗
PubMed1976

Spirometry in the evaluation of pulmonary function.

Spirometry should be more widely used in routine examinations. Equipment should meet the individual physician's or hospital's needs and include either a dependable water-sealed spirometer or an easily calibrated and accurate electronic spirometer. Justifiable concern over the reliability of electronic spirometers has resulted in requests to determine performance standards for these medical devices. Predicted normal standards must apply to the particular spirometer. Recommended tests are those of vital capacity (VC), forced vital capacity (FVC), one-second forced expiratory volume (FEV(1)), the ratio of one-second forced expiratory flow (FEF200-1200) and forced midexpiratory flow (FEF25-75 percent). The maximum voluntary ventilation (MVV) test may be useful for evaluation of work disability and detection of extrathoracic obstruction. Additional consideration may be given to measurements of total lung capacity (TLC) to discriminate between restrictive and obstructive impairment and the forced end-expiratory flow (FEF75-85 percent) to detect mild small airway obstruction. At this time, flow-volume curves measurement cannot be justified for routine clinical use.

Humans↗
PubMed1975

Movement of neurosecretory product through the anatomical compartments of the neural lobe of the pituitary gland. An electron microscopic autoradiographic study.

Electron-microscope autoradiographs have been prepared from the neural lobes of the pituitary glands of rats which had received intracisternal injections of [35S] cysteine at various times before gland removal. The rate of appearance and disappearance of autoradiographically demonstrable radioactivity in the neural lobe closely paralleled that previously determined, biochemically, for radioactive hormones and neurophysins. Radioactivity was appreciably associated with the undilated parts of neurosecretory axons only during the first few hours after injection of the label. The axonal dilations were subdivided into those in which small vesicles could be seen ("endings") and those in which no small vesicles could be seen ("swellings"). Radioactivity appeared first in "endings" and then in progressively larger and larger profiles of "swellings". It appeared that newly arrived granules were found close to the limiting membrane of the nerve swelling and that as time progressed they moved deeper and deeper into the swelling. On the basis of the results, suggestions were made for an anatomical explanation of the readily-releasable pool of hormone which has been demonstrated pharmacologically.

Animals↗
PubMed1975

Endocrine neurons.

Explore the source record for details and available documents.

Action Potentials↗
PubMed1975

Normal values and evaluation of forced end-expiratory flow.

A new spirometric measurement was performed with 803 healthy, nonsmoking men and women. Using the forced vital capacity curves, the forced end-expiratory flow (FEF75-85%) had a negative correlation with age and a positive correlation with height. Prediction formulas and nomograms were constructed. Comparison with the forced mid-expiratory flow (FEF25-75%) showed generally larger correlation coefficients for physical characteristics and coefficients of variation for the FEF75-85%. Expressing both the FEF75-85% and FEF25-75% as ratios of forced vital capacity did not improve the coefficients. The mean flow rates of 75 male smokers were compared with 213 non-smokers 30 to 49 years of age. The FEF75-85% significantly distinguished between a group of smokers and a group of nonsmokers, but the FEF25-75% showed no significant difference. In 9 patients with presumed peripheral airways disease, FEF25-75% ranged from 70 to 110 per cent of predicted normal but FEF75-85% was 30 to 72 per cent of predicted. An extensively studied control group of 22 healthy, asymptomatic, nonsmoking subjects had FEF75-85% values of 80 to 163 per cent of predicted. Both small groups of 9 patients and 22 control subjects had FEF75-85% values within 1.65 standard error of estimate. In subgroups of 319 persons, use of 75 per cent of predicted mean for FEF75-85% was of greater value in attempting to screen normal from abnormal population than using 1.65 standard error of estimate. The FEF75-85% is suggested as a useful simple ventilatory test to detect early obstructive pulmonary disease.

Adult↗