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Biomedical subjects

C P Stowell

Publications and source records attributed to C P Stowell.

At least 19 recordsLinked to original sources
PubMed2005

What happened to blood substitutes?

Concerns about the safety and adequacy of the blood supply have fostered twenty years of research into the so-called "blood substitutes" among them the oxygen carriers based on modified hemoglobin. Although none of these materials has yet been licensed for use in North America or Europe, the results of research and clinical trials have increased our understanding of oxygen delivery and its regulation. In particular, the examination of the basis for the vasoactivity observed with some of the hemoglobin based oxygen carriers has led to the insight that several colligative properties of hemoglobin solutions, such as their diffusion coefficient for oxygen, viscosity and colloid oncotic pressure, are important determinants of efficacy.

Animals↗
PubMed2002

A prospective, randomized clinical trial of universal WBC reduction.

BACKGROUND: Recipient exposure to allogeneic donor WBCs results in transfusion complications for selected populations of recipients. Whether or not WBC reduction should be universally applied is highly controversial. STUDY DESIGN AND METHODS: In a general hospital, a randomized, controlled clinical trial of conversion to universal WBC reduction was conducted. Patients (11%) with established medical indications for WBC-reduced blood were not eligible. All other patients who required transfusion were assigned at random to receive either unmodified blood components or stored WBC-reduced RBCs and platelets. Analysis for each patient was restricted to the first hospitalization. RESULTS: All eligible patients (n = 2780) were enrolled. Three specified primary outcome measures were not different between the two groups: 1) in-hospital mortality (8.5% control; 9.0% WBC-reduced; OR, 0.94 [95% CI, 0.72-1.22]; p = 0.64); 2) hospital length of stay (LOS) after transfusion (median number of days, 6.4 for control and 6.3 for WBC-reduced; p = 0.21); and 3) total hospital costs (median, $19,500 for control and $19,200 for WBC-reduced, p = 0.24). Secondary outcomes (intensive care LOS, postoperative LOS, antibiotic usage, and readmission rate) were not different between the two groups. Subgroup analysis based on patient age, sex, amount of blood transfused, or category of surgical procedure showed no effect of WBC reduction. Patients who received WBC-reduced blood had a lower incidence of febrile reactions (p = 0.06). CONCLUSION: A beneficial effect of conversion from selective to universal WBC reduction was not demonstrated.

Adolescent↗
PubMed1999

An open-label, randomized study to compare the safety and efficacy of perioperative epoetin alfa with preoperative autologous blood donation in total joint arthroplasty.

A multicenter, randomized, open-label, parallel-group study was conducted to compare the safety and efficacy of perioperative recombinant human erythropoietin (Epoetin alfa) with the safety and efficacy of preoperative autologous donation (PAD) in total joint arthroplasty. A total of 490 patients scheduled for total joint (i.e., hip or knee) surgery and having hemoglobin (Hb) levels > or = 11 to < or = 13 g/dL were randomized to receive weekly doses of subcutaneous Epoetin alfa on preoperative Days -21, -14, and -7, and on the day of surgery, or to participate in a PAD program. The mean baseline Hb level in both groups was 12.3+/-0.6 g/dL, increasing to 13.8 g/dL in the Epoetin alfa-treated group and decreasing to 11.1 g/dL in the PAD group before or on the day of surgery. In the PAD group, 156/219 (71.2%) patients were transfused with autologous blood, and 42/219 (19.2%) patients were transfused with allogeneic blood. A smaller proportion, 27/209 (12.9%) patients, in the Epoetin alfa-treated group were transfused with allogeneic blood (P = .078 compared with the PAD group). Moreover, patients in the PAD group received a total of 325 units of blood (79 allogeneic units and 246 autologous units) compared with patients in the Epoetin alfa group who received a total of 54 units of blood. The mean postoperative Hb level was 11.0 g/dL in the Epoetin alfa-treated group and 9.2 g/dL in the PAD group. Compared with the PAD arm, mean Hb levels measured preoperatively, postoperatively on Day 1, and at discharge visits were significantly greater in the Epoetin alfa-treated arm (P < .0001 ).

Age Factors↗
PubMed1998

Perceptions and preferences of autologous blood donors.

BACKGROUND: The public's perception of autologous blood donation and transfusion as a worthwhile alternative to allogeneic blood transfusion increased dramatically with discovery of the human immunodeficiency virus. However, new concerns are being raised about the health outcomes and cost-effectiveness of the procedure. As more restrictive guidelines for autologous blood donation evolve, opposition from patients concerned about exposure to allogeneic blood may arise. Physicians' ability to reassure patients and garner their support for more restrictive policies requires an understanding of patients' concerns. The motivations, perceptions, and preferences of patients currently participating in autologous blood donation programs were investigated in this study. STUDY DESIGN AND METHODS: Results from two questionnaire studies of 647 autologous blood donors are presented. The questionnaires assessed demographics, risk perceptions, preferences, willingness to pay, and reactions to different interventions designed to decrease patient preference for autologous blood donation. RESULTS: Patients expressed a strong preference for the availability of autologous blood and indicated that they would be willing to pay substantial amounts of money even if the procedure were not covered by insurance. Despite education about the low risks of complications from allogeneic transfusions, an aversion to allogeneic transfusion and a willingness to pay for autologous blood donation persisted. Patients were not reassured by information on better infectious disease testing or physician recommendation against autologous blood donation. CONCLUSION: Patients currently participating in autologous blood donor programs strongly prefer continued access to this procedure, primarily because they remain concerned about the complications of allogeneic transfusions. They may not be significantly reassured despite increasingly rigorous and costly improvements in donor and component screening.

Attitude↗
PubMed1997

Accelerated acute rejection of an apparent A2 renal allograft in an O recipient: report of a case with flow cytometric analysis.

We report a case of accelerated acute rejection of a renal allograft from a presumed ABO histo-blood group A2 donor in an O recipient, in which all of the published criteria for compatibility had been met. Flow cytometric analysis of the A and H antigen expression on the kidney donor's erythrocytes suggested that this donor did not have an A2 phenotype, but rather another subgroup of A. Some of the reported cases of accelerated acute rejection of A2 renal allografts in O recipients may have resulted from misapplication of the results of standard lectin agglutination to the transplant setting. The current case suggests that a more sophisticated method of ABO phenotyping, such as erythrocyte flow cytometric analysis, may be necessary in the transplant setting.

ABO Blood-Group System↗
PubMed1995

Red cell alloimmunization after a bone allograft.

BACKGROUND: Alloimmunization to blood group antigens other than ABH after bone allografting is uncommon. To date, examples of alloimmunization to blood group antigens other than ABH have been limited to the Rh system. CASE REPORT: A 20-year-old woman received an allogeneic bone graft following resection of an osteosarcoma. The patient had received no blood components and denied any pregnancies. Alloimmunization was detected and alloantibodies were identified by standard serologic techniques. Fourteen months after the bone graft, anti-Fya and anti-Jkb were identified in her serum. CONCLUSION: Alloimmunization to blood group antigens other than ABO and Rh may follow bone allografting.

Adolescent↗
PubMed1990

Additional fucosyl residues on membrane glycoproteins but not a secreted glycoprotein from cystic fibrosis fibroblasts.

Glycopeptides derived from peripheral membrane glycoproteins of skin fibroblasts of seven patients with cystic fibrosis (CF) had an increase in fucosyl residues when compared with those of seven age, race and sex matched controls (Pediatr Res 1985;19:368-374). To further define these results, the membrane glycopeptides which bound to immobilized lentil lectin and thereby enriched in fucosyl residues linked alpha 1----6 to N-acetylglucosamine attached to asparagine, were Pronase digested, partially purified and examined by 500-MHz 1H-NMR spectroscopy. The CF derived glycopeptides had two different features when compared to those from Controls (1) an increased number of fucosyl residues linked alpha 1----6 to the N-acetylglucosamine attached to asparagine and (2) fucosyl residues linked alpha 1----3 to a branch N-acetylglucosamine. The glycopeptides from both sources were of the di and triantennary type containing sialic acid linked alpha 2----3 and alpha 2----6 to galactose in an approximate molar ratio of 3:2 and 2:1, from CF and Control, respectively. Glycopeptides derived from a glycoprotein, fibronectin, secreted from CF fibroblasts were also examined by 1H-NMR spectroscopy and showed no evidence of fucosyl residues linked alpha 1----3 to branch N-acetylglucosamine and a lesser percentage of core fucose than found in the peripheral membrane glycopeptides. These results define further the altered fucosylation of the CF peripheral membrane glycoproteins.

Carbohydrate Sequence↗
PubMed1986

Characterization of human fibronectin glycopeptides from cystic fibrosis and control skin fibroblasts.

Fibronectins isolated from different species and tissue sources are glycosylated differently. We report here a characterization of the glycopeptides of fibronectin isolated from the culture medium of skin fibroblasts from patients with cystic fibrosis together with age-, race-, and sex-matched control subjects. The characterization of this fibronectin is of special interest because it is derived from: a non-fetal, cellular source; eight different individuals; and cystic fibrosis and control individuals. The fibronectin glycopeptides were purified by gel-permeation chromatography and Con A-Sepharose and were analyzed by anion-exchange chromatography and affinity columns of immobilized 5-hydroxytryptamine and lectins. One half of the glycopeptides of skin fibroblast fibronectin were shown to contain biantennary oligosaccharides which were core-fucosylated and partially sialylated. Although the remaining half was a complex mixture of glycopeptides, there was remarkably little inter-individual variation. No difference between cystic fibrosis and control subjects was discernible by the techniques employed here. Unlike the biantennary glycopeptides of human plasma fibronectin, those from skin fibroblast fibronectin were core-fucosylated and less highly sialylated. However, compared to human cellular fibronectin glycopeptides from fetal sources, those from skin fibroblast fibronectin were both more highly fucosylated and sialylated.

Adolescent↗
PubMed1980

The role of extra-hepatic tissues in the receptor-mediated plasma clearance of glycoproteins terminated by mannose or N-acetylglucosamine.

The mannose- and N-acetylglucosamine-specific pathway for the clearance of mammalian glycoproteins has been characterized by using 125I-labelled neoglycoproteins, glycosidase-treated orosomucoid and lysosomal glycosidases (beta-glucuronidase and beta-N-acetylglucosaminidase) as probes. There are two components to this pathway in vivo; one liver-dependent and the other extrahepatic or liver-independent. Cells that mediate clearance by the latter component of the pathway are present in spleen, bone and in elements of the reticuloendothelial system, but not in the kidney. Glycoproteins that possess terminal mannose, glucose or N-acetylglucosamine residues, including various lysosomal enzymes, are rapidly cleared from plasma via this pathway. Glucose-terminated glycoproteins are recognized by two pathways in the intact animal; the hepatic galactose-specific pathway and the mannose/N-acetylglycosamine-specific pathway, which is present in liver and in peripheral tissues. Following removal of the liver by surgical evisceration, glucose-terminated glycoproteins are cleared whereas glycoproteins bearing galactose are not cleared. Uptake of 125I-labelled neoglycoproteins and agalacto-orosomucoid by isolated alveolar macrophages closely mimics clearance in vivo by the mannose/N-acetylglucosamine pathway. Neoglycoproteins terminated by mannose, glucose or N-acetylglucosamine all compete with 125I-labelled agalacto-orosomucoid for uptake by receptor-mediated pinocytosis. The extent of substitution of the neoglycoproteins is a critical determinant of their inhibitory potency. It is proposed that mononuclear phagocytes are in important component of the clearance pathway in vivo. The mannose/N-acetylglucosamine pathway may be important in the regulation of extracellular levels of various glycosylated macromolecules, including lysosomal hydrolases.

Abdomen↗
PubMed1980

Preparation of some new neoglycoproteins by amidination of bovine serum albumin using 2-imino-2-methoxyethyl 1-thioglycosides.

The cyanomethyl 1-thioglycosides of beta-D-galactose, 6-O-methyl-beta-D-galactose, alpha-L-arabinose, beta-D-fucose, beta-L-fucose, beta-D-glucose, beta-D-xylose, beta-D-allose, alpha-D-mannose, 2-acetamido-2-deoxy-beta-D-glucose, 2-acetamido-2-deoxy-beta-D-galactose, 2-deoxy-beta-D-glucose, and 3-O-methyl-beta-D-glucose were prepared from the respective pseudothiourea derivatives and chloroacetonitrile. The nitrile function in the aglycon of the cyanomethyl 1-thioglycosides was converted to a methyl imido ester by treatment with sodium methoxide in methanolic solutions, thereby affording the 2-imino-2-methoxyethyl 1-thioglycosides [Lee, Y.C., Stowell, C.P., & Krantz, M.J. (1976) Biochemistry 15, 3956-3963]. The stability of these reagents was investigated. The 2-imino-2-methoxyethyl 1-thioglycosides were then used to attach carbohydrates to bovine serum albumin. Amidination could be accomplished within a few hours in a pH range of 7-10. The extent of amidination could be controlled by varying the ratio of imido ester to protein amino group. These new neoglycoproteins were used to determine stereospecificity of the rabbit hepatic carbohydrate-binding system [Stowell, C.P., Lee, R.T., & Lee, Y.C. (1980) Biochemistry (following paper in this issue)].

Amidines↗
PubMed1980

Studies on the specificity of rabbit hepatic carbohydrate-binding protein using neoglycoproteins.

The binding of amidinoneoglycoproteins of bovine serum albumin to rabbit liver membranes was measured. Derivatives of bovine serum albumin to which equivalent amounts of beta-D-Gal, 6-O-Me-beta-D-Gal, beta-D-Fuc, alpha-L-Ara, beta-D-Glc, beta-D-Xyl, and beta-D-GalNAc had been attached bound to the membranes equally well. The attachment of alpha-D-Man, beta-L-Fuc, beta-D-GlcNAc, beta-D-allose, 3-O-Me-beta-D-Glc, and 2-deoxy-beta-D-Glc did not promote strong binding. The specificity of binding to the membranes was confirmed by measuring the binding of neoglycoproteins to the purified rabbit hepatic carbohydrate-binding protein immobilized on Sepharose 4B. The results indicate that, for binding, (1) neither the 6-OH (D-Fuc) nor the 5-CH2OH (L-Ara; D-Xyl) is required, (2) the 4-OH can be axial (D-Gal; L-Ara) or equatorial (D-Glc; D-Xyl), (3) the 3-OH must be equatorial (D-Glc) not axial (D-All) nor may it be substituted (3-O-Me-D-Glc), (4) the 2-OH must be equatorial (D-Glc) not axial (D-Man) and must be present (2-deoxy-D-Glc), and (5) the 2-OH can be replaced by an equatorial acetamido group if the 4-OH is axial (D-GalNAc) but not if it is equatorial (D-GlcNAc).

Animals↗