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Biomedical subjects

B A Cross

Publications and source records attributed to B A Cross.

18 recordsLinked to original sources
PubMed1992

A major binding protein for leukemia inhibitory factor in normal mouse serum: identification as a soluble form of the cellular receptor.

A protein that specifically binds leukemia inhibitory factor (LIF) has been isolated from normal mouse serum by using four successive fractionation steps: chromatography on a LIF affinity matrix, anion-exchange chromatography, size-exclusion chromatography, and preparative native gel electrophoresis. The purified LIF-binding protein (LBP) is a glycoprotein with an apparent molecular mass of 90 kDa that specifically binds 125I-labeled murine LIF with an affinity comparable to that of the low-affinity cellular LIF receptor (Kd = 600 pM). N-terminal sequencing has identified this protein as a soluble truncated form of the alpha chain of the cellular LIF receptor. LBP is present in normal mouse serum at high levels (1 microgram/ml) and these levels are elevated in pregnant mice and reduced in neonatal mice. Since normal serum concentrations of LBP can block the biological actions of LIF in culture, LBP may serve as an inhibitor of the systemic effects of locally produced LIF.

Amino Acid Sequence↗
PubMed1979

Dependence of phrenic motoneurone output on the oscillatory component of arterial blood gas composition.

1. The hypothesis that respiratory oscillations of arterial blood gas composition influence ventilation has been examined. 2. Phrenic motoneurone output recorded in the C5 root of the left phrenic nerve and the respiratory oscillations of arterial pH in the right common carotid artery were measured in vagotomized anaesthetized dogs which had been paralysed and artificially ventilated. 3. The effect of a change in tidal volume for one or two breaths on phrenic motoneurone output was measured with the inspiratory pump set at a constant frequency similar to, and in phase with, the animal's own respiratory frequency. A reduction of tidal volume to zero or an increase by 30% led to a corresponding change of mean carotid artery pH level. The changes of carotid artery pH resulted in a change of phrenic motoneurone output, predominantly of expiratory time (Te) but to a lesser extent of inspiratory time (T1) and also peak amplitude of 'integrated' phrenic motoneurone output (Phr). Denervation of the carotid bifurcation blocked this response. 4. The onset of movement of the inspiratory pump was triggered by the onset of phrenic motoneurone output. When a time delay was interposed between them, the phase relationship between respiratory oscillations of arterial pH and phrenic motoneurone output altered. The dominant effect was to alter Te; smaller and less consistent changes of Phr and T1 were observed. 5. When the inspiratory pump was maintained at a constant frequency but independent of and slightly different from the animal's own respiratory frequency (as judged by phrenic motoneurone output), the phase relationship between phrenic motoneurone output and the respiratory oscillations of pH changed breath by breath over a sequence of 100-200 breaths, without change of the mean level of arterial blood gas composition. Te varied by up to 30% about its mean value depending on the phase relationship. Ti and Phr were also dependent on the phase relationship but varied to a lesser extent. The changes were comparable to the results obtained in paragraph 4. 6. It was concluded that phrenic motoneurone output is dependent in part on its relationship to the respiratory oscillations of arterial blood gas composition. 7. Information concerning a transient ventilatory disturbance is stored in the arterial blood in the form of an altered pattern of the respiratory oscillations of blood gas composition; this in turn can change breathing by an effect on the carotid bodies.

Action Potentials↗
PubMed1978

Discovery and application: lessons from animal research.

The cumbersome administrative machinery for agricultural research set up following the Rothschild Report is criticised and the view challenged that mission-oriented research is quicker, cheaper and more useful than problem-oriented research. Examples are give from two areas of biological study, corpus luteum physiology and cell membranes, to illustrate the rapid application of basic discoveries to livestock health and production.

Agriculture↗
PubMed1976

Animal, vegetable or cerebral: brains in agricultural production.

Recent developments in brain research seem to have passed unnoticed in veterinary and agricultural circles. Yet they have transformed views on the subject and, Dr Cross argues, made study of the brain mandatory for future advance in animal health and production.

Agriculture↗
PubMed1976

The effect of anaesthesia of the airway in dog and man: a study of respiratory reflexes, sensations and lung mechanics.

1. The effect of breathing an anaesthetic aerosol of 5% bupivacaine hydrochloride has been assessed in dog and man. 2. In the dog, the cough reflex was abolished and the Hering-Breuer inflation reflex severely impaired or abolished; breathing became slower and deeper; no pathological changes were found in the lungs of these dogs. 3. In man, no untoward effects resulted from a 10 min period of aerosol inhalation; there were no systematic effects on airway resistance or lung volumes and the cough reflex in response to either tactile or chemical (citric acid aerosol) stimulation was invariably abolished. The Hering-Breuer inflation reflex was impaired, but this was not associated with any change in resting ventilation. The Ve/CO2 response was enhanced after aerosol anaesthesia; subjects felt an exaggerated dyspnoea. The aerosol anaesthesia abolished the afferent pathway of a reflexly elicited bronchoconstriction in one subject. There was no effect on the ability to hold the breath, or on the quality of the associated sensation. 4. Control aerosols of sodium chloride solution or phosphate buffer produced no effects. Control experiments with intravenous infusions of bupivacaine proved that none of the effects could have been produced by systemic effects of the absorbed anaesthetic. 5. Plasma concentrations of bupivacaine in man did not exceed a recognized toxic level. The experiments demonstrate a safe reversible anaesthesia of the airways in man lasting for a period of 10-20 min.

Aerosols↗
PubMed1975

The effect of varying tidal volume on the associated phrenic motoneurone output:studies of vagal and chemical feedback.

Two groups of dogs were anaesthetised, paralysed and artificially ventilated using a respirator driven by the phrenic motoneurone output, electrically processed to resemble transpulmonary pressure. In one group, blood gases were maintained constant with closed-chest cardiopulmonary bypass; the second group were studied without "bypass". Therefore it was possible to determine the relative contributions of vagal and chemial feedback to the effect of altering the depth of an inspiration on the associated phrenic motoneurone output. Mono-exponential regressions between change of respirator gain and changes in both inspiratory time and peak amplitude of the processed phrenic signal were found for all dogs. The rate of rise of the processed phrenic signal usually changed in the direction of the change in respirator gain, suggesting the presence of vagal positive feedback during eupnoeic breathing. After vagotomy, all responses were absent in the "bypass" group and small in the "non-bypass" group. These experiments quantitate the role of pulmonary vagal afferent discharge, in phase with inspiration, in the regulation of phrenic motoneurone output in a closed-loop situation.

Animals↗
PubMed1975

Endocrine neurons.

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Action Potentials↗