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Biomedical subjects

M Green

Publications and source records attributed to M Green.

At least 1,009 records · Page 56Linked to original sources
PubMed1966

The effects of ventilation of dogs with different gas mixtures on airway calibre and lung mechanics.

1. Dead space (CO(2)-front method), lung compliance, cervical tracheal volume change and total lung resistance were measured simultaneously in anaesthetized dogs, paralysed or open-chest, and the responses to nerve section and stimulation and to ventilation of the dogs with different gas mixtures were studied.2. Bilateral cervical vagotomy changed all four parameters in a way consistent with airway dilation, and bilateral vagal stimulation had the opposite actions. A weak airway dilator role was indicated for the sympathetic nerves.3. Ventilation with 4% CO(2), 8% CO(2) or 10% O(2) changed all four parameters as if the airways had constricted, and 100% O(2) caused oppossite, but weaker, responses.4. The responses to the three airway constricting gas mixtures were present, but reduced in intensity, after bilateral cervical vagotomy and some even weaker responses were present after additional bilateral sympathectomy.5. During restoration of airway smooth muscle tone by electrical stimulation of the distal ends of the cut vagus nerves, administration of CO(2)-rich or hypoxic gas mixtures had no greater effect than during controls with vagi cut but without stimulation.6. No dilator responses to hypercapnia or hypoxia were seen, either in innervated or denervated trachea and airways.

Animals↗
PubMedDate not supplied

Analysis of morphine and its 3- and 6-glucuronides by high performance liquid chromatography with fluorimetric detection following solid phase extraction from neonatal plasma.

A rapid, sensitive and simple to operate high performance liquid chromatographic method for the simultaneous determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in plasma is described. The drug and its metabolites were extracted from plasma using commercially available reversed phase octylsilane bonded silica columns (1 mL Bond Elut C8, 50 mg). Chromatographic separation of morphine and its metabolites was achieved using a mobile phase, consisting of 2 mM sodium dodecyl sulphate in 0.05% phosphoric acid:acetonitrile (71.5:28.5 by volume), at a flow-rate of 1.2 mL/min, in conjunction with a Waters Nova-Pak C18 column (300 x 3.9 mm). The analytical column was used in combination with a Guard-Pak module containing a Nova-Pak C18 Guard-Pak insert. Using fluorescence detection (excitation 245 nm, emission 335 nm), plasma levels in the region of 5-10 micrograms/L for the drug and its metabolites can be detected with only 200 microL of plasma. The method has been applied to studies of the disposition of morphine and its metabolites in premature neonates requiring mechanical ventilation who were receiving the drug intravenously; preliminary findings in patients at steady state are presented.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Spatial variation of natural radiation and childhood leukaemia incidence in Great Britain.

This paper describes an analysis of the geographical variation of childhood leukaemia incidence in Great Britain over a 15 year period in relation to natural radiation (gamma and radon). Data at the level of the 459 district level local authorities in England, Wales and regional districts in Scotland are analysed in two complementary ways: first, by Poisson regressions with the inclusion of environmental covariates and a smooth spatial structure; secondly, by a hierarchical Bayesian model in which extra-Poisson variability is modelled explicitly in terms of spatial and non-spatial components. From this analysis, we deduce a strong indication that a main part of the variability is accounted for by a local neighbourhood 'clustering' structure. This structure is furthermore relatively stable over the 15 year period for the lymphocytic leukaemias which make up the majority of observed cases. We found no evidence of a positive association of childhood leukaemia incidence with outdoor or indoor gamma radiation levels. There is no consistent evidence of any association with radon levels. Indeed, in the Poisson regressions, a significant positive association was only observed for one 5-year period, a result which is not compatible with a stable environmental effect. Moreover, this positive association became clearly non-significant when over-dispersion relative to the Poisson distribution was taken into account.

Air Pollution, Indoor↗
PubMedDate not supplied

Pharmacotherapy of the hospitalized young adult schizophrenic patient.

The authors surveyed pharmacotherapy in a group of hospitalized 18 to 35-year-old young adult patients (N = 286) with a DSM-III diagnosis of schizophrenia. Drug use comparisons were made between patients with a 180 day or less hospitalization (short-stay, N = 226) and those with a 366+ day hospitalization (long-stay, N = 60). Psychotropic drug usage during the initial 180 and most-recent 180 days of treatment of the long-stay group was compared with the total episode of the short-stay group. Antiepileptic, antidepressant, lithium and anxiolytic/sedative/hypnotic agents, were used in significantly more of the long-stay than short-stay patients. This increase was not observed between the two groups for the initial 180 days of the long-stay group but was observed during the most recent 180 days of treatment. Antipsychotic mean daily doses and patterns of use in the two length of stay groups were similar. Chlorpromazine (CPZ) dosage was significantly increased in long-stay patients compared with short-stay patients (P less than .05).

Adult↗
PubMedDate not supplied

Influence of lung volume and rib cage configuration on transdiaphragmatic pressure during phrenic nerve stimulation in man.

Transdiaphragmatic pressure was recorded during bilateral supramaximal percutaneous phrenic nerve stimulation at 1 Hz (twitch Pdi) to investigate the effect of lung volume and rib cage configuration on diaphragm contractility in man. Stimulations were performed in 5 normal supine subjects at resting end expiration (FRC) and at lung volumes above and below FRC, during relaxation against a closed airway and during isovolume manoeuvres. Twitch Pdi at FRC was 24.4 cm H2O. At lung volumes above FRC, twitch Pdi decreased by 7.04 +/- 3.2 cm H2O per litre of volume change. At lung volumes below FRC, twitch Pdi increased by 12.4 +/- 8.6 cm H2O per litre of volume change. When the diaphragm was lengthened during an isovolume manoeuvre at FRC, twitch Pdi increased. A similar relationship between lung volume and twitch Pdi was obtained during stimulations performed with abdominal binding. These results demonstrate that the pressure developed by the diaphragm during phrenic nerve stimulation is significantly affected both by increases and decreases in lung volume and by the rib cage configuration at which stimulation is performed.

Adult↗