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Biomedical subjects

G R Standen

Publications and source records attributed to G R Standen.

At least 37 records · Page 2Linked to original sources
PubMed1996

Evaluation of a new, integral, whole blood filter (RS2000) system for prestorage leucodepletion of SAG-M red cells.

Residual donor leucocytes are responsible for many adverse transfusion reactions. Prestorage leucodepletion may ameliorate these effects and enhance product quality. We studied a bottom and top (BAT) system incorporating an integral filter for whole blood leucodepletion. Our evaluation assessed leucodepletion efficiency as well as in vitro SAG-M red cell quality and storage characteristics. Sixty-six units of blood were collected; test units into the Optipac-pLuS system and controls into the standard triple pack configuration. Test units were held for 4-6 h at room temperature (rt) or 12-18 h at 4 degrees C. The mean leucocyte counts for the SAG-M red cells in the quality and storage trial were 0.6 x 10(6) (rt hold), 0.05 x 10(6) (4 degrees C hold) and 2500 x 10(6) (controls). We observed no significant differences between the groups for Na+, ATP, 2,3-DPG, glucose, lactate and pH during the 49 d storage. The control group, however, showed a greater increase in haemolysis and K+ with time. Autologous in vivo 24 h red cell recovery, after 42 d storage, was > 75%. Adjustment of processing parameters in subsequent studies gave leucodepleted SAG-M red cells with minimal cell loss (9.19%) plus acceptable haemoglobin content (46-76 g/U) and haematocrit (54-62%). This system achieved > 3.5 log leucodepletion with all but one unit containing < 1 x 10(6) leucocytes. The product quality is good and the system suitable for routine use in blood centres.

Blood Component Removal↗
PubMed1996

Postmortem diagnosis of Factor V Leiden from paraffin wax embedded tissue.

Activated protein C resistance resulting from Factor V Leiden is an important inherited thrombophilia disorder which is found in 3.5% of people in the UK. The genetic defect can be detected using the PCR and the diagnosis can be made postmortem from paraffin wax embedded tissue. The presence of Factor V Leiden should be sought in all cases of unexplained sudden death resulting from venous thromboembolism.

Journal Article↗
PubMed1996

UHG-based mutation screening in type 2B von Willebrand's disease: detection of a candidate mutation Ser547Phe.

We have recently described a novel mutation screening technique for the diagnosis of type 2B von Willebrand's disease (vWD). Analysis involves the use of a synthetic universal heteroduplex generator (UHG). To test the validity of the technique, we have applied UHG screening to seven type 2B vWD patients of previously unknown genotype. Characteristic heteroduplex patterns for Arg543Trp and Val553Met mutations were found in three patients and one patient, respectively. A fifth patient gave a novel pattern and direct sequencing revealed a hitherto unreported candidate mutation (Ser547Phe) 8 bases downstream of an "identifier" deletion in the UHG molecule. The two remaining patients gave normal heteroduplex patterns; an Arg578Gln mutation was identified by PstI digestion in one individual and no mutation could be identified in the sequence covered by the UHG in the final patient. Using a combination of UHG technology and restriction analysis, over 85% of type 2B vWD patients can be rapidly diagnosed by genotype.

Amino Acid Sequence↗
PubMed1995

Human Rh D monoclonal antibodies (BRAD-3 and BRAD-5) cause accelerated clearance of Rh D+ red blood cells and suppression of Rh D immunization in Rh D- volunteers.

The use of prophylactic anti-D to prevent Rh D immunization in Rh D- women and subsequent hemolytic disease in Rh D+ infants is widespread, but has led to shortages of the anti-D Ig. With the aim of substituting monoclonal anti-D for Rh D prophylaxis, we have compared the abilities of monoclonal and polyclonal anti-D to clear Rh D+ red blood cells (RBCs) infused into Rh D- male volunteers and to suppress Rh D immunization. Two human monoclonal antibodies (MoAbs), BRAD-3 (IgG3) and BRAD-5 (IgG1), produced from stable Epstein-Barr virus-transformed B-lymphoblastoid cell lines, were selected because of their proven in vitro activity in promoting RBC lysis in antibody-dependent cell-mediated cytotoxicity assays. RBC clearance was assessed by intravenous injection of 3 mL of 51chromium-labeled D+ RBCs into 27 volunteers 48 hours after intramuscular injection of monoclonal or polyclonal anti-D. Further 3-mL injections of unlabeled D+ cells were administered at 6 and 9 months to induce immunization. Blood samples were taken throughout the 12-month period of study for the serologic detection of anti-D. The mean half-life (t50%) of RBCs in 7 recipients of 300 micrograms BRAD-5 (5.9 hours) was similar to that in 8 recipients of 500 IU polyclonal anti-D (5.0 hours), whereas D+ cells were cleared more slowly in some of the 8 subjects injected with 300 micrograms BRAD-3 (mean t50% 12.7 hours) and in 1 individual administered 100 micrograms BRAD-3 (t50% 41.0 hours). The rate of RBC clearance in both groups administered 300 micrograms monoclonal anti-D correlated with the amount of antibody bound per cell, determined by flow cytometry. There was no evidence of primary immunization having occurred in any subject after 6 months of follow-up. Five of 24 subjects produced anti-D after one or two further injections of RBCs, confirming that they were responders who had been protected by the monoclonal or polyclonal anti-D administered initially. Four of these responders were recipients of monoclonal anti-D (3 BRAD-3, 1 BRAD-5). One individual who received BRAD-5 produced accelerated clearance of D+ RBCs at the third unprotected RBC challenge but did not seroconvert. This study shows that the human MoAbs BRAD-3 and BRAD-5 can prevent Rh D immunization, and indicates that they may be suitable replacements for the polyclonal anti-D presently used in prophylaxis of Rh D hemolytic disease of the newborn.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Acute promyelocytic leukaemia (M3): relapse with acute myeloblastic leukaemia (M2) and dic(5;17) (q11;p11).

Secondary leukaemia following treatment of M3 acute promyelocytic leukaemia (APL) is a rare event. We describe a patient in remission following chemotherapy for APL who relapsed with M2 acute non-lymphoblastic leukaemia (ANLL). The original t(15;17) (q22;q21) chromosome translocation was lost and replaced by a clone containing a dic(5;17) (q11;p11) abnormality. Southern genomic analysis demonstrated re-arrangements of the retinoic acid receptor varies; is directly proportional to (RAR varies; is directly proportional to) and PML genes in the APL blasts at presentation but not in the M2 ANLL marrow at relapse. The significance of unbalanced 5;17 translocations as markers for therapy-related secondary leukaemia is discussed.

Blotting, Southern↗
PubMed1995

Prestorage white cell reduction in saline-adenine-glucose-mannitol red cells by use of an integral filter: evaluation of storage values and invivo recovery.

BACKGROUND: Prestorage white cell (WBC) reduction in blood components may decrease the incidence of adverse reactions and improve component quality. A bottom-and-top system with an integral third-generation WBC-reduction filter has been studied. STUDY DESIGN AND METHODS: Whole blood was collected from 30 healthy donors: from 20 by using a blood container system with an integral filter and from 10 controls by using a standard blood container system. Ten test units were buffy coat-depleted, stored for 72 hours at 4 degrees C, and then filtered, while an additional 10 test units were buffy coat-depleted and filtered at room temperature within 8 hours of collection. All units were stored at 4 degrees C for 42 days and sampled weekly. RESULTS: The mean WBC content of the 72-hour, 4 degrees C units was 0.33 x 10(6), that of the room-temperature units was 2.6 x 10(6), and that of the buffy coat-depleted controls was 460 x 10(6) (p < 0.0005). No significant differences were found among lactate, glucose, sodium, potassium, and plasma hemoglobin levels in the three groups. ATP and 2,3 DPG levels were significantly better preserved in control units than in 72-hour, 4 degrees C units (p = 0.016 and p = 0.032, respectively), but not better than in the room-temperature units. Significant differences were observed between pH values in filtered units and both groups of test units (p = 0.016). In biologic terms however, these differences were small. Red cells from an additional eight healthy volunteer donors were processed by an 8-hour room-temperature method and stored for 35 days. Studies in vivo 24-hour recovery of autologous red cells were performed by transfusing a radiolabeled (51Cr plus 131I-albumin) aliquot after 35 days' storage. Good recovery (mean > 80%) was found by both the single- and double-isotope-label methods. Recovery was significantly greater when calculated by the single-isotope method (p = 0.02). CONCLUSION: The combination of buffy coat removal and filtration in the blood container system with an integral filter achieved effective WBC reduction (> or = 3 log10 reduction from whole blood) without biologically significant detriment to in vitro or in vivo storage values.

Adenine↗
PubMed1995

Factor XIIIA Calgary: a candidate missense mutation (Leu667Pro) in the beta barrel 2 domain of the factor XIIIA subunit.

Molecular analysis performed on a Canadian family with congenital factor XIII deficiency revealed a homozygous missense mutation (Leu667Pro) in exon 14 of the A subunit gene in three affected siblings. The mutation results from a T-to-C transition at nucleotide position 2087 and generates a new Msp1 restriction site. Digestion of an amplified fragment containing exon 14 with this restriction enzyme enabled the heterozygous allele to be identified in both parents (who were third cousins) and three other family members. SSCP analysis detected no additional mutations in the coding or consensus splice sequences of the A subunit gene. The mutant nucleotide substitution was absent in 60 normal alleles and 10 unrelated patients with XIIIA deficiency. Leu667 is located in the carboxyl terminal beta barrel 2 domain of the A subunit molecule. Computer modelling based on 3D crystallographic data predicts that the mutant protein has aberrant folding and is likely to be rapidly degraded following translation.

Factor VIIIa↗
PubMed1995

Rapid genotype analysis in type 2B von Willebrand's disease using a universal heteroduplex generator.

A new diagnostic technique based on DNA heteroduplex analysis has been used to identify specific point mutations in the von Willebrand's factor (vWF) gene of patients with von Willebrand's disease type 2B. Molecular analysis in these patients has shown previously that their mutations are clustered in a short region of sequence in exon 28 of the vWF gene. The principle of the method involves heteroduplex formation between amplified genomic sequence containing the defect and an exon 28 vWF gene universal heteroduplex generator (UHG). The UHG is a synthetic vWF gene exon 28 homologue which contains a number of sequence mismatches designed to generate allele specific heteroduplexes for each type 2B mutation. Individual mutant genotypes are identified by characteristic banding patterns following polyacrylamide minigel electrophoresis. The technique is rapid, simple, inexpensive, and is ideally suited for adoption by non-specialist haematology laboratories for screening purposes.

Base Sequence↗
PubMed1994

Autoimmune neutropenia manifesting as recurrent oral ulceration.

There are many causes of recurrent oral mucosal ulceration, particularly gastrointestinal, mucocutaneous, and hematologic disease. The present report details the features of a patient with recurrent oral ulceration caused by autoimmune neutropenia.

Autoimmune Diseases↗
PubMed1994

Genetic analysis in a female manifesting haemophilia B.

A 5 year old female child presented with a psoas haematoma as the first manifestation of haemophilia B. Molecular genetic studies were performed to investigate the inheritance of the disorder and the mechanisms by which females may express the haemophilia B phenotype are discussed.

Child, Preschool↗
PubMed1993

Telomeric associations in a patient with B-cell prolymphocytic leukaemia.

Telomeric associations were determined in bone marrow preparations from a patient with B-cell prolymphocytic leukaemia and a clonal isochromosome of the long arm of chromosome 17. Thirteen associations involved 16 chromosome arms, with preferential involvement of the short arm of chromosome 19 and the long arm of 17.

Aged↗
PubMed1993

Wiskott-Aldrich syndrome: no evidence of chromosome instability.

Patients with the immune deficiency disorder Wiskott-Aldrich syndrome (WAS) have an increased risk of malignancy, most notably non-Hodgkins lymphoma. To determine whether this susceptibility is due to chromosome instability, cytogenetic analysis was performed on phytohemagglutinin-stimulated lymphocytes from five patients with this disorder. Compared to matched controls, no excess of chromosome aberrations or structural rearrangements was identified. This study does not, therefore, support the view that WAS is a chromosome instability syndrome.

Adolescent↗
PubMed1993

Factor XIII ABristol 1: detection of a nonsense mutation (Arg171-->stop codon) in factor XIII A subunit deficiency.

Molecular analysis has been performed on a patient with coagulation factor XIII A subunit deficiency. A previously published genomic sequence indicates that exon 4 of the factor XIII A subunit gene contains two TaqI restriction sites within which arginine (CGA)-->stop (TGA) nonsense mutations are possible. Oligonucleotide primers were therefore used to amplify exon 4 by the polymerase chain reaction. TaqI digestion of the 326 base pair (bp) product derived from normal genomic DNA yielded expected fragments of 244, 73 and 9 bp in size. In the case of the patient, however, an additional fragment of 253 bp was present. Direct sequence analysis showed that the 5' TaqI site had been lost from one allele by a C-->T transition at nucleotide 598. Family studies demonstrated the mutation in the patient's father but no other first-degree relatives. This is the third independent mutation described in the factor XIII A subunit gene and the first to be identified in a patient compound heterozygous for the disorder.

Adult↗
PubMed1993

Clonality of chronic neutrophilic leukaemia associated with myeloma: analysis using the X-linked probe M27 beta.

AIMS: To determine whether myeloid proliferation was monoclonal or polyclonal in a woman with chronic neutrophilic leukaemia and myeloma. METHODS: The X-linked probe, M27 beta was used to determine the clonality of the neutrophil population by analysis of restriction fragment length polymorphisms and X inactivation pattern. RESULTS: A polyclonal pattern of X inactivation was obtained for the neutrophil population in this patient. CONCLUSION: The myeloid expansion in chronic neutrophilic leukaemia associated with myeloma represents a polyclonal reactive response to the plasma cell clone rather than a co-existent myeloproliferative disorder.

Aged↗