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Biomedical subjects

I A Sutherland

Publications and source records attributed to I A Sutherland.

71 records · Page 4Linked to original sources
PubMed1987

Counter-current chromatography. Applications to the separation of biopolymers, organelles and cells using either aqueous-organic or aqueous-aqueous phase systems.

Counter-current chromatography is a form of liquid-liquid chromatography which uses low-speed centrifugation to hold one phase of an immiscible liquid pair stationary while the other is eluted through it. Two types of countercurrent chromatography are described: one suitable for preparative/analytical separation with aqueous-organic phase systems and the other for analytic fractionations using aqueous-aqueous phase systems. Applications of both processes are described, ranging from the purification of antibiotics, pesticides, and peptides to the fractionation of whole cells.

Animals↗
PubMed1987

Practical aspects of pulsatile LHRH therapy.

The availability of miniaturized portable infusion devices has enabled the development of another important method of inducing ovulation in women with clomiphene-resistant anovulatory infertility (Labrie et al, 1984; Mason et al, 1984; Armar et al, 1986a). When cases are carefully selected and accurate ultrasound monitoring is used, very impressive conception rates are achieved (Armar et al, 1986a). The treatment is simple, effective and safe.

Adult↗
PubMed1986

The dynamics of phase partition. A study of parameters affecting rat liver organelle partitioning in aqueous two-polymer phase systems.

Separation of subcellular organelles by two-phase partition is thought to reflect differential partition of the organelles between the two phases or between one of the phases and the interface. Studies by Fisher and colleagues [Fisher & Walter (1984) Biochim. Biophys. Acta 801, 106-110] suggest that cell separation by phase partition is a dynamic process in which the partition changes with time. This is mainly due to association of the cells with sedimenting droplets of one phase in the bulk of the other. Rat liver organelle partition was studied to determine whether the same dynamic behaviour is observed. Partition was clearly time-dependent during 24 h at unit gravity, and was also affected by altering the volume ratio of the two phases and the duration of phase mixing. These results indicate that, as with cells, the partition of organelles between phases is a dynamic process, and is consistent with the demonstration that organelles adhere to the phase droplet surfaces. Optimization of the volume ratio between phases may lead to significant processing economies. Organelle sedimentation in the upper phase was significantly faster than in the isoosmotic sucrose. Theoretical modelling of apparent organelle sizes indicates that aggregation occurs in the poly(ethylene glycol)-rich upper phase. This phenomenon is likely to limit the use of this technique in organelle separations unless means can be found to decrease aggregation.

Acetylglucosaminidase↗
PubMed1984

Subcellular fractionation of rat liver homogenates using two-polymer phase systems in a toroidal-coil centrifuge.

The principal organelles of rat liver homogenates were fractionated by two-phase partition chromatography using toroidal-coil centrifugation with a mixture of dextran T 500 and poly(ethylene glycol) 6000 in 0.26 M-sucrose containing 10 mM-sodium phosphate/phosphoric acid buffer, pH 7.4. The effects of varying the following parameters on organelle elution profiles, as reflected by their marker-enzyme activities, were studied: centrifuge speed; the composition and relative proportion of dextran-rich and poly(ethylene glycol)-rich phases in the eluent; flow rate; sample volume; homogenate concentration; helix diameter; tubing bore and the number of loops in the coil. Optimal resolution of the organelles was achieved with a toroidal coil of internal diameter 1.07 mm with a 4.55 mm helix diameter on a 0.42 m-diameter rotor running at 1000 rev./min. The eluent was prepared by combining, in a ratio of 93:7 (v/v), the poly(ethylene glycol)-rich upper phase and dextran-rich lower phase obtained from a phase mixture containing 3.3% (w/w) dextran and 5.4% (w/w) poly(ethylene glycol). The flow rate of the eluent was 14ml/h. Optimal conditions for separation of the organelles were evaluated. Resolution of plasma membrane and lysosomes was achieved. Separation of endoplasmic reticulum, which showed marked heterogeneity, from plasma membrane was also demonstrated. DNA and marker enzymes for peroxisomes, mitochondria and cytosol showed distinct elution profiles.

Animals↗
PubMed1984

A miniature infuser for the pulsatile administration of LHRH.

This paper describes a compact, battery-powered infuser that is light, unobtrusive and simple to operate. A novel direct-drive method is used to deliver intermittent boluses of hormone at predetermined time intervals via a special prefilled syringe. Normal pregnancy rates were achieved in anovulatory women when infused with luteinising hormone releasing hormone (LHRH).

Biomedical Engineering↗
PubMed1984

A new generation of pulsatile infusion devices.

A selection of pulsatile infusion devices suitable for administering LHRH are described. The principles of operation and control options of the different pumps are explained, including the new compact direct-drive syringe pump. The relative merits of these infusion systems are discussed and it is concluded that size, ease of use and range of application are paramount.

Gonadotropin-Releasing Hormone↗
PubMed1983

A new miniature, open-loop, extracorporeal insulin infusion pump.

This extracorporeal insulin infuser has been designed to be compact, simple to operate, and suitable either for clinical investigations of insulin-dependent diabetes mellitus or for long term treatment of the condition. A syringe driver of unconventional design is used, and the syringe will be available prefilled with insulin, specially formulated at standard strength for long term infusion. The device is electronically controlled to give variable rates of basal infusion, preset by switch and supplemented by bolus infusions demanded by pushbutton prior to meals. Sufficient insulin is carried in the syringe to meet the needs of most diabetics for at least a week without refilling, and the battery life is commensurately long. Signalling of the mealtime dose regime, and of alarm and failure conditions is by audible means. Insulin will most commonly be delivered subcutaneously, though other routes are possible.

Biomedical Engineering↗
PubMed1978

A cervimeter for continuous measurement of cervical dilatation in labour-preliminary results.

We briefly review instruments that have been used to measure cervical dilatation and describe the development of a new cervimeter. Curves derived from cervical dilatation and intrauterine pressure traces are presented in a form that clearly records the activity of the uterus and the response of the cervix to individual contractions. Our results suggest a new concept for behaviour of the cervix in labour.

Anthropometry↗
PubMed1976

The development of an instrument for monitoring dilatation of the cervix during labour.

The measurement of cervical dilatation during labour is of fundamental importance to the obstetrician as it indicates the progress of labour. This paper reviews instruments that have been used to measure cervical dilatation in the past and describes the development of an instrument, originally intended to measure both effacement of the cervix and cervical dilatation, but which, because of technical problems, resulted in an instrument measuring cervical dilatation only. The instrument is non-traumatic, accurate, and easy to apply. As well as the clinical application, the instrument has been found useful in studying mechanism of dilatation. Preliminary results have shown that the cervix opens in an oscillatory manner dictated by the strength and period of uterine contractions. It can even close slightly following a series of weak contractions. Further clinical trials are planned.

Cervix Uteri↗
PubMedDate not supplied

Meeting the problems of first-generation insulin infusion pumps: clinical trial of a new miniature infuser.

We designed and constructed a new miniature, open-loop insulin infusion pump specifically to overcome the problems of many first generation insulin infusers. Special features are small size, adjustable volumetric basal infusion rate, rapid electronically mediated prandial insulin boosts, facility for doubling and halving the basal infusion rate and/or prandial delivery, and alarms for low battery state, motor over-run, stoppage, and control circuit malfunction. The infuser takes a specially designed syringe prefilled with short-acting insulin, sufficient in most diabetic patients for at least 7 days treatment with 100 U/ml insulin. To test clinical efficacy nine insulin-dependent diabetic patients received continuous subcutaneous insulin infusion (CSII) with the new infuser for periods up to 6 mo. Four patients previously CSII-treated with a first-generation pump and five who were new to CSII achieved and maintained the expected degree of near-normoglycemia. There were no pump breakdowns and a questionnaire completed by patients during the study confirmed ease and simplicity of operation and an appreciation of the advantages of the new pump compared with one widely used first-generation infuser.

Adult↗