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Biomedical subjects

C M Ramage

Publications and source records attributed to C M Ramage.

8 recordsLinked to original sources
PubMed2003

Mineral uptake in tobacco leaf discs during different developmental stages of shoot organogenesis.

Relationships between mineral uptake and tobacco shoot organogenesis were investigated during three morphogenic phases: phase 1, days 0-10, pre-meristem formation; phase 2, days 10-20, meristem initiation and formation; and phase 3, days 20-35, growth and differentiation of induced meristems into leafy shoots. The mineral content of both shoot-forming (SF) and non-shoot-forming (NSF) media was examined over the 35-day culture period. Both SF and NSF explants rapidly consumed iron during phase 1. Nitrate uptake in SF explants was high and independent of explant growth during phases 1 and 2, but greatest and strongly correlated with growth during phase 3. Phosphorus uptake was highest in SF explants during phases 2 and 3, and correlated with explant growth. Uptake of potassium, calcium and sulphur was strongly associated with explant growth during phase 3 whereas magnesium uptake was only poorly correlated with growth. Results from this study indicate that particular minerals may have an important role in regulating development as well as generally supporting growth.

Culture Media↗
PubMed1992

Interhospital transfers by helicopter: the first 50 patients of the Careflight project.

An interhospital helicopter transfer service was set up using a dedicated helicopter fitted with medical equipment and staffed by anaesthetists. The system proved to be safe and practical. Fifty patients were referred from 38 hospitals throughout the UK, with 84% of transfers preplanned. Patients were transferred a mean distance of 118 miles (range 35-397 miles) and there was no deterioration during transfer as measured by pre and post transfer sickness scores. Twenty-eight per cent of cases could not have been practically transferred by conventional means. The death rate of 20% was lower than that reported for specially equipped and staffed land transfer systems, which may indicate less physiological deterioration in the critically ill compared to road transfer. Dedicated helicopter transfer resulted in a 50% survival rate in patients with a sickness score over 18, a group found not to survive after land transfer. There was no correlation between distance moved and outcome. A helicopter transfer system using suitable equipment and staff is a practical and safe method of moving critically ill patients between hospitals, and may be preferable to land transfer for distances in excess of 25 miles.

Aircraft↗
PubMed1991

A new portable oxygen system using liquid oxygen.

Liquid oxygen provides both practical and financial advantages in comparison with compressed oxygen when transferring patients within and between hospitals. We describe a portable liquid oxygen system and evaluate its uses and shortcomings in this area.

Ambulatory Care↗
PubMed1980

The cardiovascular effect of vasopressin in relation to its plasma concentration in man and its relevance to high blood pressure.

The cardiovascular response and the changes of plasma arginine vasopressin (AVP) concentration following graded doses of AVP infused intravenously have been defined in six normal young men. The same measurements were also made during fluid deprivation in a patient with both nephrogenic diabetes insipidus and systemic hypertension. When, following AVP infusion, mean diastolic arterial pressure increased from 72 +/- 3 mmHg (SEM) to 78 +/- 2 mmHg (SEM) in the normal subject group, mean plasma AVP increased by 14.5 fmol/ml. When the patient was deprived of water, diastolic pressure increased, despite the fluid loss, from 90 to 105 mmHg, with a comparable increase of plasma AVP concentration of 15.3 fmol/ml. Further increases of plasma AVP concentration in either the normal subjects or in the patient were not associated with further increments of arterial pressure. We suggest that under pathophysiological circumstances in man plasma AVP concentrations may achieve levels which have a significant cardiovascular effect.

Adult↗
PubMed1978

Radioimmunoassay of arginine-vasopressin in human urine and its use in physiological and pathological states.

A highly specific radioimmunoassay for arginine-vasopressin (AVP) in human urine has been developed, with a detection limit of 2.2 fmol/ml. The mean recovery of added AVP was 99.5 +/- 3.1 (S.D.)% when correction was made for the fact that an inverse relationship was observed between the recovery of AVP and the osmolality of the urine. The intra- and interassay coefficients of variation were 3.5--7 and 2.5--10% respectively. Arginine-vasopressin remains stable in urine after repeated freezing and thawing after storage at 4 or 20 degrees C for up to 7 days and at -20 degrees C for more than 3 months. During unrestricted fluid intake in normal people, the mean rate of renal excretion of AVP was 95 +/- 68 (S.D.) fmol/min. An isosmotic reduction of 9% in the plasma volume increased the excretion of AVP to 259 +/- 147 (S.D.) fmol/min. At the height of water-induced diuresis the rate of excretion fell to 70 +/- 28 (S.D.) fmol/min. Fluid deprivation for 18 h produced a moderate but significant increase in mean excretion of AVP, to a value of 116 +/- 67 (S.D.) fmol/min. Patients with compulsive water drinking showed a normal relationship between urine osmolality and the rate of excretion of AVP. In pituitary diabetes insipidus, AVP was undetectable, whereas in hereditary nephrogenic diabetes insipidus a progressive increase in the rate of excretion of AVP was observed in response to dehydration. There was a wide variation in the rate of excretion of AVP (range 126--8704 fmol/min) in patients with unexplained hyponatraemia, presumed to be due to an inappropriate secretion of antidiuretic hormone. Despite this variation, the relationship between urine osmolality and the rate of excretion of AVP clearly differed from that observed in normal people.

Adult↗
PubMed1977

Vasovagal hypotension and vasopressin release.

Mild vasovagal hypotension occurred in two normal male volunteers during insertion of indwelling venous cannulae. In spite of a rapid intravenous fluid load (3.6-4.6 litres in 90 min) both subjects passed little urine for 100 min. When the experiment was repeated without vasovagal hypotension, a rapid large diuresis followed the fluid load. The prolonged oliguria after vasovagal hypotension was the result of vasopressin release. This was demonstrated by measuring vasopressin in the blood and urine and by observing the renal response to a water load. The observation in man that a mild transient hypotensive episode may reduce urine flow for 100 min has clinical significance.

Catheterization↗