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Biomedical subjects

S Douglas

Publications and source records attributed to S Douglas.

At least 55 records · Page 3Linked to original sources
PubMed1993

Stabilization of von Willebrand factor in banked blood by leucocyte depletion.

The von Willebrand factor (vWf) activity, as measured by the ristocetin co-factor (vWf:RCo) and collagen binding (vWf:CBA) assays, declined progressively in standard blood units stored at 4 degrees C after a 2-day storage period. This loss of activity was accompanied by a loss and degradation of high molecular weight (HMW) vWf multimers. In studies using a paired design, filtration of blood with a high efficiency leucocyte-removal filter, prior to storage at 4 degrees C, led to significantly improved maintenance of vWf:RCo and vWf:CBA compared with unfiltered units (P < 0.01 after 8 days). Loss and degradation of HMW vWf decreased when blood was filtered prior to 4 degrees C storage. Filtration had no effect on vWf-associated activities when blood was stored at 22 degrees C for 10 days. These results indicate that part of the storage lesion of vWf in banked blood is due to leucocyte-mediated removal and degradation of HMW vWf. This has implications when specifying plasma for the production of vWF concentrates and may also play a role in the haemostatic lesion associated with massive transfusion of stored blood.

Blood Banks↗
PubMed1992

Modulation of fibrinogen content in cryoprecipitate by temperature manipulation during plasma processing.

In routine blood bank production of single-donation cryoprecipitate, the introduction of a 16-hour hold at 4 degrees C, with the frozen plasma units packed into polystyrene containers, resulted in plasma prethaw temperatures of -4 degrees C to -8 degrees C. This in turn resulted in cryoprecipitate fibrinogen levels that were 214 percent of those obtained when units were thawed immediately after removal from -30 degrees C storage. In scale-model production of factor VIII concentrate, plasma warmed from -30 to -10 to -15 degrees C over 18 hours before pooling and thawing yielded cryoprecipitate fibrinogen levels that were 66 percent of those found in plasma warmed to -2 to -5 degrees C over the same period. Processing -30 degrees C plasma without a warming period led to cryoprecipitate fibrinogen levels that were 40 percent of those obtained from plasma warmed to -2 to -5 degrees C. These differences were accentuated after purification of the cryoprecipitates to an intermediate-purity factor VIII concentrate. These results suggest that simple modifications in production methods allow the fibrinogen content of cryoprecipitate to be tailored to specific uses.

Blood Banks↗
PubMed1992

Red cell and platelet concentrates from blood collected into half-strength citrate anticoagulant: improved maintenance of red cell 2,3-diphosphoglycerate in half-citrate red cells.

This study confirms previous work suggesting equivalent in vitro properties in blood components prepared from donations collected into half-citrate preservative (HCPD) compared to components derived from donations collected into standard citrate-phosphate-dextrose (CPD) preservatives. In addition, red cell products harvested from HCPD donations showed significantly improved maintenance of pH over storage, and this was reflected in improved maintenance of intracellular 2,3-diphosphoglycerate (2,3-DPG). This effect was observed in whole blood and in red cells suspended in a phosphate-containing additive solution (Tuta AAS). Collection into HCPD also improved 2,3-DPG maintenance in red cell concentrates processed following an 18-hour hold at 22 degrees C. These improvements were less pronounced in red cells suspended in a non-phosphate-containing medium (Fenwal Adsol) in which a higher pH was maintained even in units collected in CPD. Platelets harvested from HCPD blood and suspended in plasma showed equivalent quality to platelets from standard donations. Some deterioration of platelet properties was observed when HCPD platelets were stored in a non-citrate synthetic medium. Together with data indicating improved coagulation factor stability, these results suggest that collection into HCPD improves stored blood quality and may also allow logistical benefits in blood component preparation.

2,3-Diphosphoglycerate↗
PubMed1992

Acute tubular necrosis: diagnosis, treatment, and nursing implications.

Acute tubular necrosis (ATN) is the most common cause of acute renal failure. Early recognition of patients who are at risk for ATN can prevent or improve the course of ATN. Acute renal failure is classified as prerenal, intrinsic, or postrenal disease. ATN is classified as a type of intrinsic renal disease. The clinical course of ATN is divided into the renal failure phase, diuretic phase, and recovery phase, with each phase having distinct symptoms and laboratory findings. Diagnosis of ATN often is complicated and confusing; understanding of laboratory findings can facilitate the critical care nurse's ability to assess those at risk for ATN. The care and treatment of the patient with ATN is complicated, and specific treatments are discussed in detail. The critical care nurse can play a vital role in identifying the patient at risk, preventing the development of ATN in those at risk, and providing appropriate care for those who develop ATN.

Humans↗
PubMed1991

Improved in-vitro quality of platelet concentrates stored in a dextrose-free synthetic medium.

The licensed balanced salt solution Plasma-Lyte, buffered with a clinical solution of sodium bicarbonate, was evaluated as a suspending fluid for platelet concentrates. Platelets suspended in this medium showed better pH maintenance over 5 days of storage compared to platelets stored in plasma (7.0 vs 6.45, P < 0.001). This was reflected in improvements in in-vitro indicators of platelet viability-hypotonic shock response (79 vs 48%, P < 0.05), aggregation to paired agonists (86 vs 62%, P < 0.05); and platelet size distribution (104 vs 119%, P < 0.001). Dissolved bicarbonate measurement showed less depletion of bicarbonate in the synthetic medium compared to plasma, which suggests a lower rate of lactate formation. A synthetic medium containing dextrose showed inferior platelet storage characteristics when compared to the plasma-lyte/bicarbonate medium in a paired study (Day 5, pH 6.53 vs 6.9, P < 0.05). The results suggest that utilization of substrates other than dextrose allows platelets to metabolize without the accumulation of lactate that leads to pH drops during storage in plasma, and continue to support the feasibility of storing platelets in a non-plasma environment.

Bicarbonates↗
PubMed1990

Use of plasma with high levels of ionised calcium in the production of model scale coagulation factor concentrates.

We have attempted to exploit the Ca2(+)-dependent stability of factor VIII in producing factor VIII concentrates of higher yield. Plasma levels of ionised calcium were increased in two ways: (a) whole blood collection into half-strength citrate CPD anticoagulant, leading to free Ca2+ levels of ca 120 microM and (b) apheresis collection of plasma which was then recalcified to free Ca2+ levels of ca 300 microM under heparin cover. Coagulation factor concentrates were prepared using model versions of our industrial scale manufacturing methods. Factor VIII yield was increased through low citrate collection. This did not compromise factor IX yield or thrombogenic potential. Use of recalcified heparinised plasma did not lead to any improvement in factor VIII yield and resulted in a marked drop in factor IX recovery, possibly from interference by heparin of factor IX binding in ion-exchange chromatography. The benefits accruable through the use of half-strength citrate CPD anticoagulant support the continued evaluation of this preservative in large scale blood collection and fractionation. The deleterious effects of heparin in charge-mediated plasma fractionations may pose serious difficulties in harvesting vitamin K dependent factors.

Anticoagulants↗
PubMed1990

Localization of beta-phycoerythrin to the thylakoid lumen of Cryptomonas phi does not involve a signal peptide.

Recent investigations have shown that, in cryptomonads, the phycobiliproteins are located within the thylakoid lumen rather than on the stromal side of this membrane as found in cyanobacteria and red algae. To examine possible mechanisms involved in targeting this protein to the thylakoid lumen, the plastid-encoded cpeB gene from Cryptomonas phi was sequenced. This gene encodes an open reading frame of 177 amino acids that is highly similar to known beta-phycoerythrin proteins. cpeB is expressed as a monocistronic transcript of approximately 680 bases. The genes for the alpha subunits of phycoerythrin are not co-transcribed with cpeB nor located anywhere near it. No evidence of amino- or carboxy-terminal extensions or interior modifications involved in directing the Cryptomonas beta-phycoerythrin into the lumen of the thylakoid could be detected. These data suggest that a novel mechanism may be involved in directing cryptomonad biliproteins to the thylakoid lumen.

Amino Acid Sequence↗
PubMed1989

Oral health promotion for institutionalised elderly.

The purpose of the present study was to develop and evaluate educational approaches specifically for improvement of oral hygiene behaviour amongst institutionalised elderly. A sample of 201 residents, 48-99 yr of age (mean age 82 yr), was selected from four different institutions in Lothian, Scotland. A clinical examination and a structured interview were conducted immediately before and 2 months after the termination of the programme. The four institutions were blind to the examiner and randomly allocated to a control group or one of the three programmes; 1) active involvement of staff only; 2) active involvement of residents only; 3) active involvement of both residents and staff. The programme comprised three 1-h sessions at monthly intervals in groups of five to six residents or members of staff. The analysis of the results showed poor oral health and oral hygiene, high objective need for oral care but low perceived need. The programme had little impact on most of the included variables and only about half of the participants remembered the programme 2 months after its termination. The implications of the study are that groups of elderly need to be differentiated further so that only well and not confused elderly participate in programmes such as this and less well and confused elderly receive regular professional support with oral hygiene.

Aged↗
PubMed1989

Microtitre plate measurement of platelet response to hypotonic stress.

The conventional method of assessing the platelet response to hypotonic stress (HSR) was adapted to allow microtitre plate technology to be used. After water is added to a platelet suspension two sequential readings are taken at 414 nM on a vertical microplate reader. The difference between the second (three minutes) and the first (one minute) was defined as the HSR. This method allowed the relation between platelet concentrate pH and viability to be confirmed, and an HSR value for use in quality control was established. The method correlated well with the conventional technique and permitted measurement of undiluted samples as well as of products with a high free haemoglobin concentration.

Blood Platelets↗
PubMed1989

Clinical nurse specialist: a facilitator for clinical research.

The role of the clinical nurse specialist is continuing to expand to include participation in clinical research. There is, however, a lack of clinical researchers available to conduct nursing research. A clinical nurse specialist with a joint appointment between a clinical and an academic setting can facilitate clinical research through collaboration. Such collaborative efforts can result in improved patient care and nursing practice. This article describes several major collaborative models used to join the academic and practice settings and discusses their strengths and weaknesses. It also describes in detail a collaborative approach in which the clinical nurse specialist play a more pivotal role by acting as a facilitator for the collaboration. We discuss the formation of the collaborative team, the roles of the participants, and the research plan of the team. Suggestions for implementing this model in other settings are offered.

Clinical Nursing Research↗
PubMed1987

Detection of prostaglandins by high-performance liquid chromatography after conversion to p-(9-anthroyloxy)phenacyl esters.

p-(9-Anthroyloxy)phenacyl bromide (panacyl bromide) undergoes rapid reaction with the carboxyl group of prostaglandins in the presence of N,N-diisopropylethylamine in acetonitrile-tetrahydrofuran (4:1). The resulting prostaglandin panacyl esters are strongly uv absorbing with a lambda max at 253 nm and an epsilon of 174,280 in acetonitrile. The lower limit of detection of prostaglandins was approximately 200 pg with uv detection (254 nm) and about 30 pg with fluorescent detection (exitation 253 and emission 445 nm) using normal-phase HPLC. The reactivity of panacyl bromide with 23 prostaglandins as well as prostaglandins released by human lung tissues was investigated.

Chemical Phenomena↗
PubMed1986

Drink tea, America!

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Cariostatic Agents↗