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Biomedical subjects

M W Rampling

Publications and source records attributed to M W Rampling.

49 records · Page 3Linked to original sources
PubMed1976

The sulphite precipitation method for fibrinogen measurement; its use on small samples in the presence of fibrinogen degradation products.

A technique based on precipitation by sodium sulphite (Na2SO3) has been developed for measuring the fibrinogen concentration of small (100 mul) samples. This technique offers technical advantages over the thrombin-clotting method, especially when measuring dilute solutions. Measurements made with the sulphite technique on fibrinogen solutions on plasma samples were not significantly different from those obtained with the thrombin-clotting method.

Fibrin Fibrinogen Degradation Products↗
PubMed1975

Observations on the effect of CO2 and temperature on the sickling phenomenon.

The explanation of the effect of CO2 on the sickling phenomenon has, in the past, been based solely on the alteration of the oxygen affinity of haemoglobin induced by the CO2, and hence solely on the oxygen saturation of the haemoglobin. A re-investigation of this phenomenon, reported here, shows that this explanation is inadequate; rather, a full explanation requires the use of Perutz's hypothesis that the haemoglobin molecule can exist in various conformationally distinct states, the relative concentrations of which are dependent not only on the oxygen saturation of the molecules but also on other factors such as pH and 2,3-diphosphoglycerate (DPG) concentration. The effect of temperature on the sickling phenomenon is explained in a similar fashion. Low temperature is found to have no effect on the morphology of irreversibly sickled cells.

Anemia, Sickle Cell↗
PubMed1975

A comparison of the effects of incubation on cells containing haemoglobin S or haemoglobin A.

1. A centrifugal packing technique has been used to investigate the effect of incubation on the flexibility of erythrocytes containing normal (Hb A) or sickle-cell (Hb S) haemoglobin. The effects on cell morphology and on the reversibility of morphological changes were also investigated. 2. The two types of cell reacted similarly to incubation. Sickling of the Hb-S was shown not to be responsible for the production of irreversibly deformed cells in these circumstances. 3. It is concluded that for both cell types the membrane inflexibility, cellular deformation and morphological irreversibility induced by the incubation were due to metabolic depletion.

Cell Membrane↗
PubMedDate not supplied

Flash freezing of erythrocyte suspensions.

Freezing whole blood in bulk usually results in severe cellular destruction through the action of ice crystals and osmotic effects in the freezing liquid. The potential of flash freezing blood aerosols onto a liquid nitrogen surface as a means of inhibiting cellular damage was studied in this work. Three commercial spraying devices were employed to spray-freeze either whole blood or concentrated erythrocyte suspensions, using hydroxyethyl starch (HES) as a cryoprotectant. The integrity and viability of the processed cells were assessed by measuring gross rheological properties and the extent of hemolysis. Cells were found to be susceptible to the very high shear stresses imposed by some of the spraying devices. Bulk freezing of blood, even in the presence of cryoprotectant, resulted in complete cellular destruction. Whereas flash freezing was capable of substantially reducing the level of hemolysis to 12.6% and preserving the cellular deformability.

Aerosols↗
PubMedDate not supplied

Blood rheology and cardiovascular risk factors in type 1 diabetes: relationship with microalbuminuria.

Whole blood and plasma viscosity, erythrocyte aggregation and deformability, plasma fibrinogen, lipids, lipoproteins, apolipoproteins, and measures of blood glucose control were compared between 21 Type 1 diabetic patients with microalbuminuria (overnight albumin excretion rate 30-200 micrograms min-1) and 21 patients with albumin excretion below this range matched for age, sex, and duration of diabetes. Patients with microalbuminuria had significantly higher glycosylated haemoglobin (9.4 +/- 1.6 (+/- SD) vs 7.9 +/- 1.8% (normal range 5.0 to 7.6%)), total-cholesterol (5.6 +/- 1.1 vs 4.6 +/- 1.3 mmol l-1), apolipoprotein B (0.82 +/- 0.21 vs 0.66 +/- 0.14 g l-1), and apolipoprotein B:A1 ratio (0.58 +/- 0.18 vs 0.50 +/- 0.15) than those without microalbuminuria (all p less than 0.05). HDL-cholesterol was also raised (1.71 +/- 0.46 vs 1.43 +/- 0.37 mmol l-1, p less than 0.05). Lipoprotein(a) concentration was possibly higher in the microalbuminuric group (median (95% Cl) 105 (82-140) vs 72 (52-114) mg l-1, p = 0.06). No differences were seen in any of the rheological measurements. These results confirm the presence of potentially atherogenic lipoprotein changes in Type 1 diabetic patients with microalbuminuria, but suggest that altered blood rheology does not predate the development of nephropathy.

Adult↗
PubMedDate not supplied

PTFE, collars, and patches.

The results of PTFE grafts to crural vessels have been sufficiently poor for some surgeons to consider primary amputation for critical ischemia in the absence of suitable lengths of autologous vein from arm or leg. However, the results of two anastomotic techniques using a short segment of interposed vein, are encouraging. We have attained 1-year patency rates of 74% (n = 72) using PTFE with the Taylor patch technique (personal communication) and 47% (n = 27) using PTFE with Miller collar anastomoses to distal crural vessels. To investigate the hemodynamic benefit of these techniques, they have been tested (using a pulsatile flow model incorporating standard pressure, viscosity, graft and vessel length, and anastomotic angle) against a standard end-to-side PTFE anastomosis to cadaver internal mammary artery. There was no significant difference in flow between the anastomotic methods. Downstream resistance was dictated by the diameter of the recipient vessel providing a vein interposition technique was used (r greater than .80), but this relationship was lost if a direct PTFE-arterial anastomosis was performed (r = .06), suggesting additional anastomotic resistance in the latter. This constitutes experimental evidence to suggest that direct PTFE-arterial anastomosis risks hemodynamically important technical errors, which are avoidable by the use of either the Miller collar or Taylor patch.

Anastomosis, Surgical↗