Biomedical subjects

A Cheng

Publications and source records attributed to A Cheng.

At least 73 records · Page 4Linked to original sources

PubMed1999

The effect of fenofibrate on insulin sensitivity and plasma lipid profile in non-diabetic males with low high density lipoprotein/dyslipidaemic syndrome.

Non-diabetic males, particularly those with very low levels of high density lipoprotein (HDL) type cholesterol and high levels of very low density type lipoprotein (VLDL), are associated with insulin resistance and decreased insulin sensitivity. The evidence that elevation of HDL cholesterol and diminution of triglycerides with drugs, with improvement in insulin sensitivity is still lacking. In the treatment of the dyslipidaemic syndromes with hypolipidaemic drugs, the associated metabolic abnormality of insulin resistance/sensitivity has to be addressed. We investigated the degree of decreased insulin sensitivity in 23 patients with low HDL and/or raised triglycerides by measuring the fasting, first and second hour insulin levels during an oral glucose tolerance test (OGTT) and repeated the measurements after a 6-month course of fenofibrate. The insulin levels were correlated with the OGTT, blood pressure, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides measured before and at the end of the trial. The serum insulin at the second hour of the OGTT fell from 100.79 +/- 42.79 mU/l to 54.56 +/- 25.43 mU/l (P < 0.0005) even though there was no change in the blood glucose level at this point. Our study shows that fenofibrate (Lipanthyl) 300 mg daily significantly raises the pretreatment low HDL cholesterol (from 0.64 +/- 0.1 mmol/l to 0.99 +/- 0.2 mmol/l) as well as lowers the triglyceride level (from 2.17 +/- 1.1 mmol/l to 1.43 +/- 0.64 mmol/l) in patients with low HDL/dyslipidaemic syndrome. The data also support the conclusion that treatment with fenofibrate increases insulin sensitivity as measured by the corresponding insulin levels of the OGTT in the study subjects who presented with very low HDL cholesterol level. There was also a decrease in blood pressure readings in our study subjects. Throughout the trial, there was no significant change in body weight or exercise level in the subjects studied.

Adult↗

PubMed1999

[A pharmacokinetic study of teniposide in intraperitoneal chemotherapy of ovarian cancer].

The objectives of this study were to determine the characteristics of pharmacokinetics of teniposide (VM-26) instilled intraperitoneally with three dosages (100 mg, 150 mg and 200 mg) and to evaluate its toxicity. Twelve patients with ovarian cancer were divided into three groups: teniposide 100 mg i.p., 5 patients; teniposide 150 mg i.p., 5 patients; and teniposide 200 mg i.p., 2 patients. Samples of ascitic fluid, blood and urine were collected after administration of these drugs in 24 hours. Concentrations of teniposide were determined with high-performance liquid chromatographic procedure. The results showed that the data collected from peritoneum and plasma were found to conform to a two-compartment open model. The peak concentration (Cmax) and the area under the curves (AUC) in peritoneal cavity and plasma were dose-dependent. The ratios of Cmax and AUC between peritoneal fluid and plasma varied within 13.46 +/- 1.89 and 7.65 +/- 2.03 respectively. The elimination half-lives (T1/2 beta) in the peritoneum and plasma of teniposide were 5.28 +/- 0.95 and 6.64 +/- 2.73 hours respectively. The volume of peritoneal distribution and its clearance were lower than those of plasma (P < 0.001). The side effects were mild and were not dependent on drug dosage. The results suggest that teniposide as an intraperitoneal therapeutic agent offers some advantages in the treatment of ovarian cancer. The tumor tissues and peritoneal growths could be bathed in a high concentration of teniposide. Teniposide is safe, reasonable in intraperitoneal chemotherapy and shows prospects in the treatment of ovarian cancer.

Adult↗

PubMed1998

Fostriecin-mediated G2-M-phase growth arrest correlates with abnormal centrosome replication, the formation of aberrant mitotic spindles, and the inhibition of serine/threonine protein phosphatase activity.

Fostriecin, a structurally unique phosphate ester, is presently under evaluation in clinical trials to determine its potential use as an antitumor drug in humans. Fostriecin has been reported as having inhibitory activity against DNA topoisomerase type II and protein phosphatases implicated in cell-cycle control. However, the relative contribution of these mechanisms to the antitumor activity of fostriecin has not yet been elucidated. In this study, after confirming that fostriecin is a potent inhibitor of serine/threonine protein phosphatase type 2A and a weak inhibitor of serine/threonine protein phosphatase type 1, we show that fostriecin inhibits approximately 50% of the divalent cation independent serine/threonine protein phosphatase (PPase) activity contained in whole cell homogenates of Chinese hamster ovary cells at concentrations associated with antitumor activity (1-20 microM). Investigations into the cellular effects produced by fostriecin treatment reveal that 1-20 microM fostriecin induces a dose-dependent arrest of cell growth during the G2-M phase of the cell cycle. Immunostaining of treated cells indicates that growth arrest occurs before the completion of mitosis and that fostriecin-induced growth arrest is associated with the aberrant amplification of centrosomes, which results in the formation of abnormal mitotic spindles. The "mitotic block" induced by fostriecin is reversible if treatment is discontinued in <24 h. However, after approximately 24-30 h of continuous treatment, growth arrest is not reversible, and treated cells die even when placed in fostriecin-free media. Correlative studies conducted with established PPase inhibitors reveal that, when applied at concentrations that inhibit PPase activity to a comparable extent, both okadaic acid and cantharidin also induce aberrant centrosome replication, the appearance of multiple aberrant mitotic spindles, and G2-M-phase growth arrest. These studies add additional support to the concept that PPase inhibition underlies the antitumor activity of fostriecin and suggest that other type-selective PPase inhibitors should be evaluated for potential antitumor activity.

Alkenes↗

PubMed1998

A critical evaluation of the planning target volume for 3-D conformal radiotherapy of prostate cancer.

PURPOSE: To determine an adequate planning target volume (PTV) margin for three-dimensional conformal radiotherapy (3D CRT) of prostate cancer, the uncertainties in the internal positions of the prostate and seminal vesicles (SV) and in the treatment setups were measured. METHODS AND MATERIALS: Weekly computed tomography (CT) scans of the pelvis (n=51) and daily electronic portal images (n=1630) were reviewed for eight patients who received seven-field 3D CRT for prostate cancer. The CT scans were registered in three dimensions to the original planning CT scan using commercially available software to measure the center-of volume (COV) motion of the prostate and SV. The daily portal images were registered to the corresponding simulation films to measure the setup displacements. The standard deviation (SD) of the internal organ motions was added to the SD of the setups in quadrature to determine the total uncertainty. Positive directions were left, anterior, and superior. Rotations necessary to register the CT scans and portal images were minimal and not further analyzed. RESULTS: The mean motion for the COV of the prostate+/-the SD was 0+/-0.9 mm in the left-right (LR), 0.5+/-2.6 mm in the anterior-posterior (AP), and 1.5+/-3.9 mm in the superior-inferior (SI) directions. The mean motion for the COV of the SV+/-the SD was 0.3+/-1.7 mm in the LR, 0.7+/-3.8 mm in the AP, and 0.9+/-3.5 mm in the SI directions. For all patients the mean isocenter displacement+/-the SD was 0+/-3.1 mm in the LR, 1.4+/-3.0 mm in the AP, and -0.4+/-2.1 mm in the SI directions. The total uncertainty for the prostate was 3.2 mm, 4.0 mm, and 4.4 mm in the LR, AP, and SI directions, respectively. For the SV, the total uncertainty was 3.5, 4.8, and 4.1 mm in the LR, AP, and SI directions, respectively. CONCLUSIONS: PTV margins of 10 to 16 mm are required to encompass all (99%) possible positions of the prostate or SV during 3D CRT. PTV margins of 7 to 11 mm will encompass the measured uncertainties with a 95% probability. PTV margins of 5 mm may not adequately cover the intended volume.

Humans↗

PubMed1998

Use of angiotensin-converting enzyme inhibitors as monotherapy and in combination with diuretics and calcium channel blockers.

Angiotensin-converting enzyme (ACE) inhibitors have earned an important place in medical therapy since their discovery about two decades ago. This family of drug has grown tremendously since the introduction of captopril in 1981. There are currently more than 14 ACE inhibitors in the world and 9 are available in the United States. Although these agents share many similarities, they differ in their pharmacokinetic properties, approved indications, and cost. This paper provides guidance for selection of ACE inhibitors by examining the pharmacokinetics, pharmacodynamics, drug interactions, adverse effects, and cost of these agents. Combination products of ACE inhibitors with either diuretics or calcium channel blockers also are reviewed.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1998

A simple mechanical mixer for small viscous lipid-containing samples.

The construction and performance characteristics of a simple device for rapid and convenient hydration and mixing of small volumes (10-500 microliters) of viscous hydrated lipid samples for use in X-ray diffraction/scattering and other applications are described. The mixer has been used successfully over the past several years in studies of the equilibrium properties of lipid mesophases and of the kinetics and mechanism of phase transitions. It is a low dead-volume (3.6-11.2 microliters) device that was built to facilitate maximal transfer of homogeneously hydrated lipid from the mixer into 1 mm diameter X-ray capillaries with minimal loss of water during transfer and sample manipulation. The device consists of inexpensive, commercially available parts, the most important of which are two microsyringes joined by a small-bore coupling needle. Also described in this report is a technique for determining the water content of the small volume, hydrated samples prepared with the mixer and an accessory for conveniently heating and/or degassing samples during mixing. Inadvertent sample heating that occurs during mixing is described.

Lipids↗

PubMed1998

A prospective cohort study of blood donors: methodological issues in the investigation of injuries and chronic diseases.

Blood donors have made important contributions to research, most notably in cross-sectional seroprevalence studies. The proposed New Zealand Blood Donors Health Study is a prospective cohort study of 30,000 New Zealand donors designed to investigate the determinants of common injuries, cardiovascular disease and cancer. While robust from an analytic perspective, the execution of prospective cohort studies in many settings is impeded by methodological, economic and organisational barriers. We examined the operational considerations of implementing a large-scale cohort study at a transfusion centre and evaluated measures taken to optimise data collection procedures. A pilot study of 1,000 participants revealed donor motivation to participate in this research was high (91% response rate). Comprehensive exposure data on lifestyle, behavioural and psychosocial factors were obtained from 95% of participants. Substantial heterogeneity in levels of potential risk factors was noted among respondents. Detailed dietary habit information and a study blood sample were obtained from 67% and 100% of participants, respectively. Study recruitment and baseline data collection was feasible during routine donor visits with minimal interruption to donor centre staff and procedures. We conclude the study design and characteristics of the regional donor program enhance the efficiency and significance of the proposed research.

Adolescent↗

PubMed1998

Pharmacodynamic evaluation of factors associated with the development of bacterial resistance in acutely ill patients during therapy.

The selection of bacterial resistance was examined in relationship to antibiotic pharmacokinetics (PK) and organism MICs in the patients from four nosocomial lower respiratory tract infection clinical trials. The evaluable database included 107 acutely ill patients, 128 pathogens, and five antimicrobial regimens. Antimicrobial pharmacokinetics were characterized by using serum concentrations, and culture and sensitivity tests were performed daily on tracheal aspirates to examine resistance. Pharmacodynamic (PD) models were developed to identify factors associated with the probability of developing bacterial resistance. Overall, in 32 of 128 (25%) initially susceptible cases resistance developed during therapy. An initial univariate screen and a classification and regression tree analysis identified the ratio of the area under the concentration-time curve from 0 to 24 h to the MIC (AUC[0-24]/MIC) as a significant predictor of the development of resistance (P < 0.001). The final PK/PD model, a variant of the Hill equation, demonstrated that the probability of developing resistance during therapy increased significantly when antimicrobial exposure was at an AUC[0-24]/MIC ratio of less than 100. This relationship was observed across all treatments and within all organism groupings, with the exception of beta-lactamase-producing gram-negative organisms (consistent with type I beta-lactamase producers) treated with beta-lactam monotherapy. Combination therapy resulted in much lower rates of resistance than monotherapy, probably because all of the combination regimens examined had an AUC[0-24]/MIC ratio in excess of 100. In summary, the selection of antimicrobial resistance appears to be strongly associated with suboptimal antimicrobial exposure, defined as an AUC[0-24]MIC ratio of less than 100.

Acute Disease↗

PubMed1998

The Syk protein tyrosine kinase is essential for Fcgamma receptor signaling in macrophages and neutrophils.

The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fcgamma receptor (FcgammaR)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk-/- embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to FcgammaR engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by FcgammaR but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the FcgammaR gamma chain, as well as Erk2 activation, was compromised in Syk-/- macrophages after FcgammaR stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from FcgammaRs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.

Abdomen↗

PubMed1998

In vitro and animal validation of bromine-76-bromodeoxyuridine as a proliferation marker.

UNLABELLED: The potential of 76Br-bromodeoxyuridine as a PET tracer for characterizing proliferation potential was investigated in multicellular tumor aggregates and in healthy rats and pigs. METHODS: Bromine-76-bromide was produced by proton irradiation of a 76Se-enriched target using a 17-MeV cyclotron and recovered by thermal diffusion. Bromine-76-BrdU was prepared from the corresponding trimethylstannate by an oxidative bromination. Multicellular aggregates from a carcinoid cell line and two bladder cancer cell lines were co-incubated with 76Br-BrdU and 3H-thymidine and the uptake and DNA incorporation analyzed. About 0.5 MBq 76Br-BrdU were injected in the tail vein of unanaesthetised Sprague-Dawley rats. Two to 36 hr later they were decapitated and the radioactivity concentration and fraction of radioactivity incorporated into DNA determined in five different organs and the blood. Parallel studies were performed in animals pretreated with hydroxyurea. In separate experiments, rats were given an injection of 76Br-bromide and organ uptake was evaluated after 20 hr. PET studies were performed in two pigs and the uptake in different organs was investigated after injection of 76Br-BrdU. In these studies, diuresis was induced by furosemide and mannitol and radioactivity in blood and organs was followed during 10 hr. RESULTS: In the cell aggregates, 30%-90% of the radioactivity was extracted in the DNA fraction. A good correlation was found between 76Br-BrdU and 3H-thymidine with respect to total uptake and DNA fraction. The DNA fraction increased from 2-10 hr after incubation. With in vivo injection in the rat, relatively high uptake of radioactivity was found in all organs, unrelated to the degree of DNA synthesis. However, inhibition by hydroxyurea occurred only in the spleen and intestines, organs which also showed a high degree of incorporation of 76Br-BrdU into DNA. In the pig, the highest in vivo uptake was observed in the red bone marrow and the intestines. In these organs, 70%-80% of the radioactivity was recovered in the DNA fraction. The concentration of radioactivity in the heart, liver and kidney was 3-10 times lower, and here the DNA fraction accounted for 10%-20% of the radioactivity. The decay-corrected radioactivity in blood and nonproliferating organs decreased with diuresis with a half-life of 13 and 16 hr, respectively. CONCLUSION: It is suggested that the radioactivity uptake as seen after the administration of 76Br-BrdU, is constituted by two parts: one relating to incorporation into DNA and one existing as free 76Br- or metabolites of 76Br-BrdU. If sufficient time has passed, 76Br- dominates other metabolites. A correct assessment of DNA-incorporated radioactivity using PET with 76Br-BrdU is not trivial and can only be made with due correction for 76Br-, using either a complementary investigation after hydroxyurea pretreatment (in animal studies) or a separate 76Br-bromide investigation. Alternatively, the free bromide can be eliminated partially through forced diuresis.

Animals↗

PubMed1997

NEAR's flyby of 253 mathilde: images of a C asteroid

On 27 June 1997, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 1212 kilometers of asteroid 253 Mathilde. Mathilde is an irregular, heavily cratered body measuring 66 kilometers by 48 kilometers by 46 kilometers. The asteroid's surface is dark (estimated albedo between 0.035 and 0.050) and similar in color to some CM carbonaceous chondrites. No albedo or color variations were detected. The volume derived from the images and the mass from Doppler tracking of the spacecraft yield a mean density of 1.3 +/- 0.2 grams per cubic centimeter, about half that of CM chondrites, indicating a porous interior structure.

Journal Article↗

PubMed1997

Fostriecin, an antitumor antibiotic with inhibitory activity against serine/threonine protein phosphatases types 1 (PP1) and 2A (PP2A), is highly selective for PP2A.

Fostriecin, an antitumor antibiotic produced by Streptomyces pulveraceus, is a strong inhibitor of type 2A (PP2A; IC50 3.2 nM) and a weak inhibitor of type 1 (PP1; IC50 131 microM) serine/threonine protein phosphatases. Fostriecin has no apparent effect on the activity of PP2B, and dose-inhibition studies conducted with whole cell homogenates indicate that fostriecin also inhibits the native forms of PP1 and PP2A. Studies with recombinant PP1/PP2A chimeras indicate that okadaic acid and fostriecin have different binding sites.

Alkenes↗

PubMed1997

Genomic organization of the human PP4 gene encoding a serine/threonine protein phosphatase (PP4) suggests a common ancestry with PP2A.

Serine/threonine protein phosphatase type 4 (PP4) belongs to a family of okadaic acid and microcystin-LR-sensitive protein phosphatases. In this study, we report the cloning and characterization of the human PP4 gene. The gene spans about 10 kb and includes one untranslated and eight translated exons. The 5' flanking region of the gene is rich in G and C (60.1%) and lacks TATA and CAAT boxes. Sequence analysis of the 5'-flanking region reveals potential binding sites for transcription factors SP1, AP1, AP2, and several gamma-IRE-CS sites. Two transcription initiation sites were mapped by ribonuclease protection analysis, one to 54 and the other to 84 bp upstream of the ATG initiation codon. PCR analysis of a human/rodent somatic cell hybrid panel maps PP4 to chromosome 16, and comparison of the PP4 gene structure with that of PP2A and PP1 suggests that PP4 is more closely related to PP2A than PP1.

Amino Acid Sequence↗

PubMed1997

The amino terminus of JAK3 is necessary and sufficient for binding to the common gamma chain and confers the ability to transmit interleukin 2-mediated signals.

JAK3 is a protein tyrosine kinase that specifically associates with the common gamma chain (gammac), a shared subunit of receptors for interleukin (IL) 2, 4, 7, 9, and 15. Patients deficient in either JAK3 or gammac presented with virtually identical forms of severe combined immunodeficiency (SCID), underscoring the importance of the JAK3-gammac interaction. Despite the key roles of JAK3 and gammac in lymphocytic development and function, the molecular basis of this interaction remains poorly understood. In this study, we have characterized the regions of JAK3 involved in gammac association. By developing a number of chimeric JAK3-JAK2 constructs, we show that the binding specificity to gammac can be conferred to JAK2 by transferring the N-terminal domains of JAK3. Moreover, those JAK3-JAK2 chimeras capable of binding gammac were also capable of reconstituting IL-2 signaling as measured by inducible phosphorylation of the chimeric JAK3-JAK2 protein, JAK1, the IL-2 receptor beta chain, and signal transducer and activator of transcription 5A. Subsequent deletion analyses of JAK3 have identified the N-terminal JH7-6 domains as a minimal region sufficient for gammac association. Furthermore, expression of the mutant containing only the JH7-6 domains effectively competed with full-length JAK3 for binding to gammac. We conclude that the JH7-6 domains of JAK3 are necessary and sufficient for gammac association. These studies offer clues toward a broader understanding of JAK-mediated cytokine signaling and may provide a target for the development of novel therapeutic modalities in immunologically mediated diseases.

3T3 Cells↗

PubMed1997

Three-dimensional organization of a human water channel.

Aquaporins (AQP) are members of the major intrinsic protein (MIP) superfamily of integral membrane proteins and facilitate water transport in various eukaryotes and prokaryotes. The archetypal aquaporin AQP1 is a partly glycosylated water-selective channel that is widely expressed in the plasma membranes of several water-permeable epithelial and endothelial cells. Here we report the three-dimensional structure of deglycosylated, human erythrocyte AQP1, determined at 7 A resolution in the membrane plane by electron crystallography of frozen-hydrated two-dimensional crystals. The structure has an inplane, intramolecular 2-fold axis of symmetry located in the hydrophobic core of the bilayer. The AQP1 monomer is composed of six membrane-spanning, tilted alpha-helices. These helices form a barrel that encloses a vestibular region leading to the water-selective channel, which is outlined by densities attributed to the functionally important NPA boxes and their bridges to the surrounding helices. The intramolecular symmetry within the AQP1 molecule represents a new motif for the topology and design of membrane protein channels, and is a simple and elegant solution to the problem of bidirectional transport across the bilayer.

Aquaporin 1↗

PubMed1997

Ice-binding mechanism of winter flounder antifreeze proteins.

We have studied the winter flounder antifreeze protein (AFP) and two of its mutants using molecular dynamics simulation techniques. The simulations were performed under four conditions: in the gas phase, solvated by water, adsorbed on the ice (2021) crystal plane in the gas phase and in aqueous solution. This study provided details of the ice-binding pattern of the winter flounder AFP. Simulation results indicated that the Asp, Asn, and Thr residues in the AFP are important in ice binding and that Asn and Thr as a group bind cooperatively to the ice surface. These ice-binding residues can be collected into four distinct ice-binding regions: Asp-1/Thr-2/Asp-5, Thr-13/Asn-16, Thr-24/Asn-27, and Thr-35/Arg-37. These four regions are 11 residues apart and the repeat distance between them matches the ice lattice constant along the (1102) direction. This match is crucial to ensure that all four groups can interact with the ice surface simultaneously, thereby, enhancing ice binding. These Asx (x = p or n)/Thr regions each form 5-6 hydrogen bonds with the ice surface: Asn forms about three hydrogen bonds with ice molecules located in the step region while Thr forms one to two hydrogen bonds with the ice molecules in the ridge of the (2021) crystal plane. Both the distance between Thr and Asn and the ordering of the two residues are crucial for effective ice binding. The proper sequence is necessary to generate a binding surface that is compatible with the ice surface topology, thus providing a perfect "host/guest" interaction that simultaneously satisfies both hydrogen bonding and van der Waals interactions. The results also show the relation among binding energy, the number of hydrogen bonds, and the activity. The activity is correlated to the binding energy, and in the case of the mutants we have studied the number of hydrogen bonds. The greater the number of the hydrogen bonds the greater the antifreeze activity. The roles van der Waals interactions and the hydrophobic effect play in ice binding are also highlighted. For the latter it is demonstrated that the surface of ice has a clathratelike structure which favors the partitioning of hydrophobic groups to the surface of ice. It is suggested that mutations that involve the deletion of hydrophobic residues (e.g., the Leu residues) will provide insight into the role the hydrophobic effect plays in partitioning these peptides to the surface of ice.

Amino Acid Sequence↗

PubMed1997

Warfarin skin necrosis in a postpartum woman with protein S deficiency.

BACKGROUND: Warfarin-induced skin necrosis is a rare and dangerous complication affecting 0.01-0.1% of patients on warfarin. Deficiencies in protein C or protein S in association with other factors have been implicated in its etiology. No report has described this disorder in the immediate postpartum period in patients with protein S deficiency. CASE: A 1-week postpartum woman with known protein S deficiency presented with skin necrosis after a previously uneventful course of warfarin. CONCLUSION: Reduced levels of free protein S during the antepartum and immediate postpartum periods predispose protein S-deficient women to warfarin skin necrosis. Previously uncomplicated courses of warfarin do not obviate the possibility of skin necrosis with future warfarin administrations. Initiation of low-dose warfarin with heparin can reduce the likelihood of this disorder.

Adult↗

PubMed1997

Recovery of extra plasma during preparation of platelet concentrates using a new centrifugation support.

During blood component preparation of standard blood donations a major loss of plasma occurs whenever platelet concentrates (PC) are produced, especially when the platelets are prepared by the platelet-rich plasma (PRP) method. This loss is partly due to the use of plasma for resuspension of the platelet pellet but the main loss is associated with the slow first spin used to prepare PRP. This slow first spin results in an undesirably low haematocrit and a red-cell concentrate which contains a large volume of trapped plasma which is lost to the fractionation plant. We have developed a method of recovering most of this plasma from the soft-spun red cells by including the red-cell concentrate (RCC) in the second spin during preparation of the platelet pellet. To allow recovery of the second spin plasma from the half-full RCC bag we have developed a simple bag support, the Perth BagRap. Development of the method proved difficult due to the high g forces but the final technique evolved was simple and inexpensive. The method was easily introduced into routine use and resulted in a 53% increase in plasma per three-product unit.

Blood Donors↗