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Biomedical subjects

R A Kahn

Publications and source records attributed to R A Kahn.

At least 145 records · Page 8Linked to original sources
PubMed1971

Effects of sodium warfarin on capillary ultrastructure.

The fine structure of capillaries from warfarin-treated animals has been compared with that from normal animals. Capillaries from treated animals show marked cytoplasmic changes characterized by loss of ground substance and decreased organelle content. The pathogenesis for these observations is postulated.

Animals↗
PubMedDate not supplied

The fate of bacteria introduced into whole blood from which platelet concentrates were prepared and stored at 22 or 4C.

Bacteria were intentionally introduced into units of whole blood. Platelet concentrates (PC) which were made from these units were stored at either room temperature (22 C) or at 4 C. In order to isolate small numbers of bacteria from a PC (i.e., 1 to 10 organisms per ml), substantial contamination (42 to 125 organisms per ml) of the whole blood was required. If the PC were stored at room temperature, all organisms except Pseudomonas aeruginosa, which was apparently killed, grew out of control within 48 hours. Storage of PC at 4 C resulted in the general maintenance of bacterial numbers. Since gross contamination of PC has only occasionally been reported, we conclude that past reports of modest contamination of platelet concentrates are primarily sampling artifacts.

Bacteria↗
PubMedDate not supplied

Storage of platelet concentrates.

The American National Red Cross has initiated a cooperative clinical study designed to evaluate the therapeutic effectiveness of fresh platelets and platelets stored at 4 or 22 C for up to 72 hours. Preliminary results, in confirmation of earlier work, indicate an inverse relationship between platelet count and bleeding time in patients with thrombocytopenia transfused with fresh platelets. Also, the observed rise in platelet count immediately following transfusion of fresh platelets is generally maintained for four to eight hours after which time it declines significantly.

Blood Cell Count↗
PubMedDate not supplied

Optimum centrifugation conditions for the preparation of platelet and plasma products.

Units of whole blood were centrifuged for various periods of times and at various speeds to prepare platelet-rich plasma. It was found that several sets of centrifugation conditions resulted in an optimum yield of platelets and plasma. This optimum was approximately 8.3 x 10(10) platelets in 245 ml of plasma. When platelet-rich plasma was centrifuged, a maximum of approximately 95 per cent of the platelets could be recovered in the concentrate. Although this maximum was also achieved by several sets of centrifugation conditions, the most efficient method was 3,800 RPM (3731 x g) for four minutes at speed.

Blood Cell Count↗
PubMedDate not supplied

The fate of bacteria in frozen red cells.

Units of blood were intentionally contaiminated with suspensions of either Aerobacter aerogenes, Escherichia coli, Bacillus subtilis, Enterobacter cloacae, Pseudomonas aeruginosa, Sarcina lutea, Seratia marcesens, Staphylococcus epidermidis, Streptococcus faecalis, Paracolabacterum aerogenoides (Enterobacter hafriae), Mima polymorpha or Acinetobacter- calcoaceticus. When inoculation was made prior to glycerolization, the subsequent glycerolization, freezing, thawing, and deglycerolization resulted in roughly a two log reduction in the number of bacteria. When inoculation was made with a final concentration of between 10(1) and 10(5) organisms per milliliter, immediately following deglycerolization or following washing without glycerolization and freezing, no increase in the number of bacteria was seen after 72 hours storage at 4 C. Three of the 12 organisms studied decreased in number during 72 hours of storage. These data suggest that the current 24-hour limit on the post-thaw storage of frozen red blood cells may be unnecessarily restrictive.

Bacteria↗
PubMedDate not supplied

The effect of refreezing previously frozen-deglycerolized red blood cells.

Frozen red blood cells, once thawed and washed, must be used within 24 hours or discarded. In this study, three units of blood underwent two freeze-thaw cycles. It was shown that red blood cell survival, ATP, and 2,3-DPG were not adversely effected. The data suggest that previously frozen red blood cells should be refrozen, rather than discarded, if not used within 24 hours of deglycerolization.

Adenosine Triphosphate↗
PubMedDate not supplied

The impact of converting to an all frozen blood system in a large regional blood center.

We studied the impact of converting to an all frozen blood system in a large regional blood center. Several basic assumptions were made including the availability of a sterile docking device which would increase the shelf life of deglycerolized blood to 72 hours. Our study indicated that the most economical manner in which to implement such a program would be to supply deglycerolized blood to all hospitals transfusing more than 500 units per year and to provide frozen units to hospitals transfusing less then this amount (those hospitals would deglycerolize the blood they use). The estimated total cost of the proposed conversion was 3.9 million dollars or a 76 per cent increase over the present operation. Relative to our present fee structure, the average cost of a unit of blood would increase 80 per cent if only frozen or deglycerolized red blood cells were distributed.

Blood Banks↗
PubMedDate not supplied

Effects of prolonged room temperature holding of whole blood intended for preparation of components.

Current FDA regulations require that platelet concentrates must be prepared within four hours of whole blood collection. To determine if this time period was critical for the harvesting of viable platelets and other blood components, whole blood was held at room temperature for four, six or eight hours after which various components were prepared. Our results indicate that up to eight hours storage had no detrimental effect on platelet yield, recovery in vivo or lifespan. AHF activity, supernatant hemoglobin and red blood cell ATP were also unaffected.

Adenosine Triphosphate↗