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Biomedical subjects

P R McCurdy

Publications and source records attributed to P R McCurdy.

At least 19 recordsLinked to original sources
PubMed1998

Cord Blood Transplantation Study (COBLT): cord blood bank standard operating procedures.

In 1995, the National Heart Lung and Blood Institute (NHLBI) solicited requests for a proposal (RFP) entitled "Transplant Centers for Clinical Research on Transplantation of Umbilical Cord Stem and Progenitor Cells." Three banks, six transplant centers, and one medical coordinating center (MCC) (Table 1) were funded with the overall goal of banking cord blood units (CBU) using a single manual of operations. Furthermore, the clinical protocols to evaluate the transplant outcome for adult and pediatric recipients of these well-characterized CBU would be analyzed in a uniform fashion. Because of the intense interest of the transplantation community in the policies and procedures for cord blood collection and processing, the principal investigators of the cord blood banks (CBB) and NHLBI elected to submit for publication the rationale and an abridged, but detailed, version of the standard operating procedures (SOP) developed between October 1996 and July 1998 prior to the initiation of the clinical protocols to be performed with these CBU. As the SOP will be refined over time, the complete SOP and subsequent amendments will be published and continually updated on the websites from the MCC-The EMMES Corporation (www.EMMES.com). All forms referred to in this document may be obtained from the EMMES website. It is hoped that the publication of this document will lay down a framework that will not only facilitate the development of other CBB but also help us more rapidly define what constitutes an "acceptable" CBU product.

Adult↗
PubMed1988

Hemolysis in sickle cell disease as measured by endogenous carbon monoxide production. A preliminary report.

To detect and quantitate temporal variations of the hemolytic rate in sickle cell disease, the authors measured endogenous carbon monoxide (CO) production in five normal subjects, nine patients with sickle cell anemia (SS) in steady clinical state, and two patients with sickle cell-hemoglobin C (SC) disease in and out of pain crises. The red blood cell life span calculated from these data (RCLSco) ranged from 81.2 to 102.9 days (mean +/- standard deviation [SD] 88.0 +/- 9.2, coefficient of variation [CV] 10.2%) for the normal subjects and 8.0-24.7 days (mean +/- SD 12.1 +/- 5.1, CV 42.1%) for those with SS. Although the individual figures for RCLSco for the normal subjects and those with SS fell within the range previously obtained by radioisotopic techniques for the respective groups, the mean values calculated from the CO technique were slightly (though not significantly) shorter for the normal subjects and about 25% shorter for the subjects with SS (P less than 0.01). Repetitive studies were performed in four subjects with SS who were clinically stable; the temporal variability in the calculated hemolytic rate differed considerably from patient to patient (CV 3.6%, 7.0%, 17.0%, 28.0%). In two patients concurrent RCLS studies were performed by the CO technique and 51Cr tagged red blood cells. In one patient, the RCLS was similar by the two techniques, in the other, a two exponent 51Cr curve did not permit calculation of RCLS. In the two patients with SC disease there was no difference in RCLSco during and after recovery from pain crisis. Although the CO technique may overestimate the turnover of circulating heme mass, especially in the presence of hemolysis, the results of serial studies in a small number of patients with SS suggest but do not prove temporal variations in hemolytic rate in SS.

Anemia, Sickle Cell↗
PubMed1983

Complications related to equipment and technique.

Automated cytapheresis, when performed by experienced operators using modern equipment, is remarkably free of adverse effects. A declining pattern of equipment failure and related problems has been recorded in the 220,000 procedures performed by the American Red Cross in the past 5 years. Other cytapheresis centers report similar findings. Current CBCS are safe and reliable, and defects in plastic disposables, while irritating, result in little danger to the donor. Operator vigilance and careful attention to the details of the procedure can eliminate the majority of serious potential complications that have been encountered to date.

Blood Component Removal↗
PubMed1982

Chronic lymphocytic leukemia: a monoclonal disease.

A black woman with chronic lymphocytic leukemia (CLL) was found to have monoclonal B lymphocytes with one type of surface immunoglobulin and one variant of G6PD (glucose-6-phosphate dehydrogenase) (G6PD A). Erythrocytes and T cells contained both G6PD A and G6PD B and hence were of polyclonal origin. The CLL cells in this patient likely arose from a developmental stage later than the step of differentiation into T and B lymphocytes. Furthermore, her erythrocytes did not arise from a stem cell affected by the CLL process.

Aged↗
PubMed1980

Oat cell carcinoma mimicking leukemia.

A patient with oat cell carcinoma had circulating carcinoma cells, which initially suggested a diagnosis of acute leukemia. The correct diagnosis was made only by histopathologic examination of the bone marrow. A case of a similar bone marrow disorder, which developed after diagnosis of oat cell carcinoma, is also presented.

Bone Marrow Examination↗
PubMed1980

Screening for abnormal hemoglobins: who, when, and how.

Sickle cell and abnormal hemoglobin screening programs should not be undertaken lightly but rather should have a specific purpose or purposes. If the aim is to detect only sickle hemoglobin, a certain strategy is necessary. If the goal is to detect all abnormal hemoglobins and genetic counseling is planned, another approach should be used. A simple solubility test detects sickle hemoglobin with high reliability, but deals with no other abnormal hemoglobins. Hemoglobin electrophoresis, followed by other tests as indicated, is then necessary to ascertain other abnormal hemoglobins in addition to hemoglobin S.

Anemia, Sickle Cell↗
PubMed1978

Proton nuclear magnetic resonance studies of hemoglobin Providence (beta82EF6 Lys replaced by Asn or Asp): a residue involved in anion binding.

High-resolution proton nuclear magnetic resonance studies of hemoglobins Providence-Asn (beta82EF6 Lys replaced by Asn) and Providence-Asp (beta82EF6 Lys replaced by Asp) show that different amino acid substitutions at the same position in the hemoglobin molecule have different effects on the structure of the protein molecule. Hemoglobin Providence-Asp appears to be in a low-affinity tertiary structure in both the deoxy and carbonmonoxy forms. Deoxyhemoglobin Providence-Asn has its beta heme resonance shifted downfield slightly from its position in normal adult hemoglobin; however, the tertiary structures of the heme pocket of hemoglobins A and Providence-Asn are very similar when both proteins are in the carbonmonoxy form. These results are consistent with the oxygen equilibrium measurements of Bonaventura, J., et al. [(1976) J. Biol. Chem. 251, 7563] which show that both Hb Providence-Asn and Hb Providence-Asp have oxygen affinities lower than normal adult hemoglobin, with Hb Providence-Asp having the lowest. Our studies of the effects of sodium chloride on the hyperfine shifted proton resonances of deoxyhemoglobins A, Providence-Asn, and Providence-Asp indicate that the beta82EF6 lysine is probably one, but not the only binding site for chloride ions.

Adult↗
PubMed1978

Delayed hemolytic transfusion reactions. An often-missed entity.

Delayed hemolytic transfusion reactions in eight persons were manifested solely or primarily by an apparently unexplained posttransfusion decrease in the hematocrit value. Alloantibodies were eventually found in all eight patients, but were sometimes undetectable for as long as 72 hours after the reaction. This did not preclude the occurrence of a new, acute hemolytic reaction. There were three instances of reversible renal failure complicating the reaction. In two patients, some or all of the antibodies became undetectable after four and nine months. In a third, the indirect antiglobulin reactions became considerably weaker after 12 months. Patients previously sensitized to RBC antigens should have available records inspected and a warning device (wristband or wallet card) provided to help prevent reactions caused by an anamnestic antibody rise.

Adolescent↗
PubMed1978

Irreversibly sickled cells and red cell survival in sickle cell anemia: a study with both DF32P and 51CR.

For 25 subjects with sickle cell anemia the mean red cell life span measured with Di-isopropylfluorophosphite-32P (DF32P) was 17.32 +/- 4.51 days. Performed simultaneously, the half life (T1/2 of radioactively-labelled chromium 51Cr) was 10.11 +/- 2.82 days (14 subjects). Eight additional subjects, or more than 30 per cent of those studied using both red cell tags, had 51Cr red cell survival curves better described by two exponents than by one, apparently due to two different rates of 51Cr elution from the red cells. This finding limits the value of quantitative data obtained by this procedure. A negative correlation was found between the mean red cell life span measured with DF32P-tagged cells and the proportion of irreversibly sickled cells in venous or capillary blood. A similar negative correlation was found between the red cell half survival time measured with 51Cr-tagged cells and the proportion of irreversibly sickled cells. These data are compatible with the view that repeated sickling and, in particular, the formation of irreversibly sickled cells play a distinct role in the pathogenesis of hemolysis in sickle cell anemia.

Anemia, Sickle Cell↗
PubMed1977

Microcytic hypochromic anemias.

Iron deficiency, by far the most common cause of microcytic anemia, may be traced to abnormal bleeding, rapid growth, or rarely, inadequate diet. A search for the source of abnormal bleeding is particularly important because it may lead to detection of an ulcer or cancer. Orally administered iron supplements usually are effective; parenteral therapy is rarely needed.

Anemia, Hypochromic↗
PubMed1976

Hemoglobin providence. Functional consequences of two alterations of the 2,3-diphosphoglycerate binding site at position beta 82.

Position beta 82 in human hemoglobin (Hb) is normally occupied by lysine, a positively charged residue that is involved in the binding of anionic cofactors. This residue is substituted by a neutral residue in Hb Providence Asn and by a negatively charged residue in Hb Providence Asp. Hb Providence Asp shows more differences from Hb A than does Hb Providence Asn in studies of the kinetics and equilibria of ligand binding. For both forms, homotropic (cooperative) interactions are normal with n values of 2.5 to 2.7, while heterotropic (pH and anion) interactions are reduced greatly. The reduction in anion sensitivity is attributed to the absence of a positive residue at position beta 82. Reduction in pH sensitivity may be due to a ligand-linked change in the pK of a neighboring residue, beta 143 histidine, which normally is not a Bohr group. This change in pK would act in opposition to the normal Bohr effect. Reduction in the net positive charge of the central cavity has a further consequence. Relative to Hb A, both Hb Providence Asn and Hb Providence Asp show decreased oxygen affinities at neutral pH in the absence of cofactors. This suggests that in Hb A the binding of anionic cofactors directly influences the oxygen affinity by neutralizing the charged groups of the diphosphoglycerate binding site and thus stabilizing the low affinity (T) conformation. From pH 6 to 9 in the presence of 1 M NaCl, where all the charged groups may be masked, the oxygen-binding properties of Hb A and the Hb Providence mutants are identical. Moreover, subunit dissociation of the liganded Hb Providence mutants appears to be increased, as is known to occur for Hb A in the presence of high salt. The results obtained with Hb Providence Asn and Hb Providence Asp illustrate how single amino acid substitutions can modify hemoglobins' pH and anion interactions without altering cooperative interactions between subunits. The alteration in cofactor effects observed with these mutants also illustrates differences between the allosteric effects induced by organic and inorganic anions.

Adult↗