The effect of temperature on the flow of diluted blood [Hct = 0.21], through 5 mu m Nuclepore filters, is described by the Arrhenius equation with an energy of activation of 27.7 kJ/mol. Plasma, diluted with PBS, is almost three times less sensitive to temperature, with an energy of activation of 9.8 kJ/mol, while red cells are of intermediate sensitivity, with an energy of activation of 14.7 kJ/mol. The most sensitive elements to changes in temperature are leukocytes, with energies of activation of 31 kJ/mol and 35 kJ/mol for fast-flowing leukocytes (granulocytes and lymphocytes) and slow-flowing leukocytes (monocytes) respectively. Hence, the major determinants of the decline in filterability of blood through micropore filters are the leukocytes. This effect is compounded when blood is kept for 10 minutes or more at 10 degrees C due to activation of granulocytes, which leads to permanent pore blocking when the affected blood is filtered at room temperature. The combination of increased passage time of leukocytes through peripheral areas at abnormally low temperatures and subsequent activation might influence the flow of blood in non-affected tissues. The effect of temperature on the filterability of red blood cells through 3 mu m filters is not described by the Arrhenius equation and the deviations are seen as a gradual change of slope rather than a sharp break between two straight lines. The data are consistent with a gradual shift in rate limiting step away from the entry event into pores, which dominates at low temperature but becomes progressively less important at elevated temperatures. The changing parameter is probably the volume of the red cell, which is less important when flow is measured through 5 mu m pores.

Erythrocytes↗

PubMedDate not supplied

Characterization of leukocytes by filtration of diluted blood.

From the known numbers and properties of normal blood cells, it is apparent that the analysis of the flow of diluted blood, through micropore filters, should allow calculation of the properties of leukocytes without the need for their prior purification. The number and transit time of a "slow" leukocyte population can be deduced by fitting the flow, of diluted blood through 5 microns membranes over about 150 s, to the appropriate mathematical model, which is chosen by the use of a suitable statistical test--the runs test. This population of leukocytes equates numerically with the monocyte population of normal blood; cells have a transit time, through 5 microns pores, of 27.7 +/- 10.9 s. The remaining "fast" leukocytes represent the sum of granulocytes and lymphocytes; their flow properties can be deduced from the measured initial flow rate of diluted blood and the estimated properties of the red blood cells. The properties of the red cells can be assessed from filtration of purified suspensions with any concentration of cells from 0.52 x 10(9)/ml to 3.0 x 10(9)/ml. The transit times for red cells and granulocytes/lymphocytes, in blood diluted with about an equal volume of buffer, are 1.36 +/- 0.17 ms and 1.48 +/- 0.33 s, respectively. The transit times of blood cells, through 5 microns pores, are therefore inversely related to their numbers in blood.

Cell Size↗

PubMedDate not supplied

Semiconstrained total elbow arthroplasty in the context of treated previous infection.

Previous infection has been considered a strict contraindication to implantation or reimplantation of an elbow prosthesis. The purpose of this study was to investigate whether these patients can in fact be successfully treated with a prosthetic arthroplasty given previous treatment of the infection. Ten consecutive prosthetic arthroplasties performed in patients with documented infections in the elbow were retrospectively reviewed. Seven of the patients had infectious complications of total elbow arthroplasties that led to resection. Two patients had previous infections from septic joints and 1 from open reduction internal fixation. The median interval of time from infection treatment to final implant was 45 months (3.8 years). All arthroplasties were performed by the same surgeon with a modified Coonrad-Morrey, semiconstrained prosthesis. Patients were monitored for clinical signs of infection including radiographic and serologic studies and clinical evaluation based on the Mayo Elbow Performance Score. Mean surveillance was 4 years (range 2.8 to 5.4 years). Eight of the 10 cases have not shown signs of infection at the latest assessment. Two have had recurrent infections. The time interval from the original infection to latest implantation did not correlate with infection recurrence. Among those 8 without recurrent infection, 7 had excellent and 1 had satisfactory results according to the Mayo Elbow Performance Score. The recurrent infections were rated as failures. The average score was 32 before and 81 after surgery. The average pain score was 15 before surgery, and the average postoperative pain score was 40. Salvage of previously infected elbows with prosthetic arthroplasty can provide excellent results in a significant proportion of patients. Although the procedure offers superior functional outcomes compared with the alternative treatment options, it is technically demanding.

Aged↗

PubMedDate not supplied

Haematology and coagulation indices in paired samples of arterial and venous blood from patients with arterial disease.

To investigate whether there are differences in haematology and coagulation indices in arterial and venous plasma, and whether those changes related to damage to the endothelium in atherosclerosis, we obtained blood samples from 22 subjects undergoing diagnostic angiography. There were no differences in any of the 15 routine haematological indices measured. There were no differences in prothrombin time, activated partial thromboplastin time, fibrinogen, tissue plasminogen activator, D-dimer, leucocyte elastase, soluble P-selectin or von Willebrand factor. In venous samples, von Willebrand factor was lower in serum than in plasma (p < 0.0001). Levels of the tissue plasminogen activator/plasminogen activator inhibitor-1 (tPA/PAI-1) complex were markedly higher in arterial blood than in venous blood (p = 0.004) and plasma viscosity was higher in venous blood (p = 0.0014). Consequently, with the exception of viscosity and the tPA/PAI complex, we can find no differences in arterial blood compared to venous blood which can contribute to the debate regarding the mechanism of damage to arterial endothelial cells but the relative protection of venous endothelial cells from injury in atherosclerosis.

Adolescent↗