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Biomedical subjects

S Rowlands

Publications and source records attributed to S Rowlands.

At least 55 records · Page 3Linked to original sources
PubMed1982

Transmission of the quantum interaction of erythrocytes.

The previously demonstrated long-range quantum mechanical interaction between human erythrocytes suspended in plasma also occurs with artificial media. Certain macromolecules dissolved in phosphate-buffered saline will transmit the interaction provided their concentration is above a minimum. Extended macromolecules transmit the interaction, whereas a compact macromolecule (albumin) does not.

Cell Communication↗
PubMed1982

Resistance to the Brownian movement of red blood cells on flat horizontal surfaces.

The movements of red blood cells (RBC), suspended in plasma, on plastic, glass, rhodium metal plate, siliconized glass, and siliconized rhodium were recorded on ciné-film and analyzed. Values for the drag coefficient were calculated, using Einstein's theory on Brownian movement, and compared with the theoretical Stokes' hydrodynamic drag. The difference between the computed and Stokes' values gave the frictional coefficient or resistance resulting from the interaction of the cells with the test surface. Of the three uncoated test surfaces, plastic was found to have the least interaction with the RBC. The frictional coefficient for plastic was found to be 1.75 X 10(-7) N s m-1 compared with a value of 2.82 X 10(-7) N s m-1 for rhodium metal, which had the largest interaction. Upon siliconization of the test surfaces, the interaction decreased by 40%. Reduction in the pH of the suspending plasma increased the interaction between the cells and the uncoated test surfaces, but the pH effect diminished when the surfaces were siliconized.

Cell Adhesion↗
PubMed1982

A quantum mechanical interaction of human erythrocytes.

Theory predicts that the membrane potential will polarize membrane molecules and cause them to vibrate coherently at a frequency of approximately 10(11) HZ. If the supply of metabolic energy exceeds a minimum value, membrane phonons may condense their momentum into a single "giant" vibrational mode. At 10(11) HZ ionic screening is small up to distances of approximately a micrometre, so forces of a range several orders of magnitude longer than chemical forces can arise. These forces may be attractive or repulsive depending on frequency. They should occur in every metabolically active membrane and may control macromolecular transport and enzyme-substrate interactions. We find that normal human erythrocytes in plasma form rouleaux faster than Brownian motion predicts. When cells are fixed in glutaraldehyde or are metabolically depleted, or if the membrane potential is brought to zero, the rate of aggregation agrees with Brownian theory. When the metabolically depleted cells are revived or if the membrane potential is restored, then the interaction returns.

Biomechanical Phenomena↗
PubMed1982

Rubella screening: organization and incentive.

Women aged 15-44 in a total population of 13,300 were screened for rubella immunity. Seventy-one per cent of the women at risk responded to a letter asking them to attend for a blood test, and of these nearly two thirds were screened. Practice expenditure on the programme was three times greater than income. We suggest a simpler, cheaper way of screening which involves minimal extra work and where an age-sex register is not required. We propose the introduction of a higher item-of-service payment for rubella vaccination.

Adolescent↗
PubMed1980

The volume of the human erythrocyte and plasma alkaline phosphatase activity.

Changes in mean red cell count (RCC), mean cell volume (MCV) and plasma alkaline phosphatase activity (ALP) were observed in a group of 33 normal male university students at a 7-week interval. Linear regression analysis shows a negative linear relationship between changes in RCC and MCV (r = -0.77, P less than 0.0005) while a positive correlation was found for changes both in ALP activity and in MCV (r = +0.37, P less than 0.025). Multiple regression analysis indicates that 70% of the variation in MCV could be accounted for by changes in RCC and plasma ALP activity (r = +0.84, P less than 0.0025).

Adult↗
PubMed1980

Intravascular hemolysis in acute mountain sickness.

A case of acute mountain sickness (AMS) is described of a fit young man while on a climbing expedition in Mexico. The subject exhibited intravascular hemolysis in addition to normal AMS symptoms. This case is reported in the hope that others will look for and report the presence or absence of intravascular hemolysis on climbing expeditions.

Acute Disease↗
PubMed1980

Red blood cell count (RCC) and volume (MCV) of three subjects in a hypobaric chamber.

Measurements of red blood cell count (RCC) and mean corpuscular volume (MCV) were made on three subjects during a 42-h continuous exposure to low barometric pressure. RCC varied insignificantly in two subjects, but increased steadily with time in the third. MCV decreased appreciably (12-14%) in all three subjects 5 h after exposure to the low pressure but returned close to baseline values after 40 h. It is concluded that 1) short exposures to low barometric pressures result in a reduction in red cell size; 2) increased red cell production in response to low oxygen levels shows individual variations.

Adult↗
PubMed1979

Erythrocyte volume and count: a linear relation descriptive of population differences.

In a sample of 215 adult males the mean red cell volume decreases linearly with increasing red cell concentration. The mean corpuscular volume and the red cell count are found uncorrelated with age of subject. Of these subjects 69 are identified as smokers and 114 as nonsmokers. Linear regression analysis shows negative linear relation for the smoking-defined groups, with slopes judged to be no different. When the regression lines are constrained to be parallel the line for smokers is displaced upward by 2.7 fl. No difference is found in mean corpuscular haemoglobin concentration or reticulocyte count. Haematocrit, haemoglobin, mean corpuscular haemoglobin are also reported. Viscosity of blood is greater in smokers. Optical determination of cell volume and area confirms the linear relation of volume and count.

Adolescent↗
PubMed1977

Electronic measurement of red cell flow in micropipettes.

The velocity of human erythrocytes in flow-through tubes of diameter less than 5 mum is measured as a function of driving pressure. The electrical resistance in the lumen of the tube increases when a cell is present, so a pulse can be generated of length inversely proportional to velocity. In the apparatus described the pulses and driving pressure are fed to a computer which derives the correlation between pressure and velocity. Experiments confirm that the resistance to flow of erythrocytes in a narrow tube is substantially the same as that of the suspending medium. The apparatus is being used to study the effects of changes in erythrocyte deformability on flow.

Capillaries↗
PubMed1975

The stages of osmotic haemolysis.

The haemolysis of individual human erythrocytes has been observed using an inverted microscope and cine-camera. 2. With each permeant (glycerol, propylene glycol, ethylene glycol, urea and water) haemolysis is a multistage process. The stages are swelling, popping, reduction in volume possibly accompanied by ion leakage and, finally, haemoglobin leakage. 3. The classical haemolysis time (Th) is made up of a swelling time (Tsw) and a stress time (Tst). Tst is not negligible and with the faster permeants it may occupy more than 75% of the haemolysis time. 4. The stress time can also be divided into two parts: a K+ leak time (TK) during which the cell shrinks and a time (THb) during which haemoglobin is leaving the cell. THb occupies a substantial part of Th, from 25 to 65%, and is relatively longer in fast haemolysis. 5. There is a wide spread in the permeability coefficient to glycerol in a population of erythrocytes. The distribution is compatible with a Gaussian distribution. The mean permeability is 1-79 X 10(-6) cm/sec and the S.D. is +/0 0-45 X 10(-6) cm/sec. 6. The correlation between haemolysis time and swelling time for individual erythrocytes is poor, especially for fast haemolysis. Consequently, a measure of the distribution of haemolysis time does not give a related distribution of the swelling time or of the calculated permeability for individual erythrocytes.

Cell Membrane Permeability↗
PubMed1975

Flow through the bile duct after cholecystectomy.

The human bile duct has no intrinsic motility, but following cholecystectomy, flow through the bile duct is governed by the intraductal pressure generated by the liver, by the resistance to flow through the duct and sphincter at the terminal end of bile duct and by intraduodenal pressure. Pressure-flow experiments were performed upon 50 patients with biliary T-tube drainage following cholecystectomy and choledochostomy; nine patients had also undergone transduodenal sphincterotomy. Saline solution was introduced into the bile duct at controlled pressures, ranging from zero to 30 centimeters of water, while recordings were made of the flow rate of saline solution, intraduodenal pressure and respiratory movements. Although the flow rate of saline solution increased as its perfusion pressure was increased, three types of variation in flow were also recorded: rhythmic arrests of flow, occurring four to eight times per minute, believed to be due sphincteric contractions; nonrhythmic arrests of flow, lasting up to one minute, believed to be due to sphincteric contraction, and variations in flow associated with changes in intraduodenal pressure. The resistance to the flow of saline solution and the variations in flow rate were also similar in the patients who had undergone sphincterotomy. This study supports the view that sphincteric activity is present followingcholecystectomy, that the choledochal sphincter has rhythmic activity which differs from that of duodenal motility and that sphincter probably opens and closes continuously in a rhythmic manner during fasting periods in patients who have undergone cholecystectomy.

Bile Ducts↗