PubMed · 6814562
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R L Thomas. 1982. Tissue compensation--difference compensators.. https://doi.org/10.1259/0007-1285-55-659-859
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In-line leukocyte reduction filters (LRF) are available for use with an automated plateletpheresis (PPH) system. Initially, 62% of PPH units produced with such a filter (LRF6, N = 29) had postfiltration (POF) white blood cell (WBC) counts < 5 x 10(6), with a mean POF WBC of 42 x 10(6). In an attempt to decrease POF WBCs, PPH were rested 30 to 60 minutes before filtration with LRF6. A new, larger-volume LRF (LRF10) was also assessed for its efficiency of leukodepletion. A total of 625 PPH, 490 filtered with LRF6 and 135 with LRF10, were evaluated using prefiltration (PRF) and POF samples. Mean prefiltration WBC loads averaged 80 x 10(6) (range, 60-88 x 10(6)) using seven combinations of filters, collection software, and PRF rest periods. Ninety-three percent of PPH units rested prior to filtration with LRF6 (N = 237) had < 5 x 10(6) WBC POF, with a mean of 5 x 10(6) WBC POF. All PPH units filtered with LRF10 (N = 135), whether rested or not, had < 5 x 10(6) WBC POF, with a mean WBC count of 0.2 x 10(6) POF. Mean platelet (PLT) yields POF ranged from 3.1 to 3.4 x 10(11). A PRF rest decreased mean POF WBC counts in products filtered with LRF6. The LRF10 consistently produced PPH with < 5 x 10(6) WBC POF. Blood centers must thoroughly validate equipment utilized in the production of blood components.
On-line membrane plasma fractionation techniques have made semiselective removal of pathological macromolecules practical. However, several problems such as cryogel formation exist when the procedure is performed at ambient temperature. Cryogel formation takes place when heparinized plasma is cooled below 35 degrees C and when it tends to occlude the pore structure of the secondary filter membrane resulting in a poor molecular cut off of the macromolecular filter. Thermofiltration is one of the on-line plasma fractionation techniques used when warming plasma from 37 to 42 degrees C to prevent cryogel formation. Thermofiltration enhanced the performance of the lipofilter (Kuraray 4A) and demonstrated better molecular cut off between low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol than double filtration plasmapheresis (DFPP). An improved lipofilter (Kuraray 5A) has been developed and has shown better molecular cut off between LDL cholesterol and HDL cholesterol than the 4A filter. However, cryogel formation still occurred even using the 5A filter during the DFPP procedure. Thermofiltration maintains the performance of the secondary filter by preventing cryogel formation. Further studies are required to evaluate the enhanced performance of the 5A filter by thermofiltration.
A questionnaire was sent to all clinics in the Public Dental Health Service in Orebro County in 1989 and 1993. The survey comprised questions about X-ray film and developing technique. The questionnaire of 1993 was accompanied by questions on the type of dental X-ray film and collimator each dentist used, altogether 175 dentists. The results showed that Kodak Ektaspeed dental X-ray film was used by 53% of the dentists in 1993. The mean number of months to the expiry date for all film packages irrespective of film type increased from a mean of 7.5 months to a mean of 13 months from 1989 to 1993. Only 11% of the Ektaspeed film packages in 1989 had a base plus fog < or = 0.25, whereas the figure in 1993 was 30%. Rectangular collimation adjusted to the size-2 film (31 mm x 41 mm) was used by 36% of the dentists in 1993. In 1993, 88% of the clinics used automatic processing, and in 85% of the clinics both automatic and manual processing was used. The processing time and temperature varied greatly for both automatic and manual processing. The results indicate that film and developing procedures in Swedish general dental practice are not always in accordance with the recommendations and guidelines of the Swedish National Radiation Protection Institute (SSI) and that attempts should be made to improve dentists' behavior with regard to radiation safety. A major dose reduction would be achievable without jeopardizing diagnosis if the regulations of the SSI were followed by using the fastest available film and optimum developing procedures.(ABSTRACT TRUNCATED AT 250 WORDS)