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Biomedical subjects

D Powars

Publications and source records attributed to D Powars.

At least 37 records · Page 2Linked to original sources
PubMed1982

A modified life table method to study congenital genetic disorders: an application in sickle cell anemia.

A modified life table procedure is introduced designed to study the survival of patients with congenital genetic disorders with the endpoint defined by a complication or death. It uses the ages of the patients as the time axis as in "population' or "current' life tables, and it allows patients to enter and exit the study as in survival life tables. The procedure uses the exact length of time that each patient is observed in the study to determine the conditional probabilities of developing the complication. The proposed procedure is especially helpful in studying recurrent complications or events that occur frequently. The proposed life table procedure is demonstrated in the study of the conditional probability of developing a sickle cell crisis in 509 patients with sickle cell anemia (SS) with different number of prior crises. The demonstration is intended to illustrate the use of the proposed method and not to investigate the clinical severity of sickle cell anemia. It was found that the risk of crisis was to investigate the clinical severity of sickle cell anemia. It was found that the risk of crisis was positively related to the number of prior crises in SS patients (P less than 0.001). This trend was significant in the first three decades of life.

Actuarial Analysis↗
PubMed1982

Evaluation of the surgical aspects of staging laparotomy for Hodgkin's disease in children.

Experience with 72 children in which the type of staging laparotomy recommended by the Intergroup Hodgkin's Disease in Childhood Study (IHDCS) was employed (1967-1981) is reviewed. Laparotomy altered the stage in 35% of these patients including advance in stage (I-II to III-IV) in 24 patients, and reduction in stage (III to II) in one patient. In adults, Stage III disease is divided into III1 and III2 on the basis of the presence or absence of lower abdominal node involvement; and prognosis is significantly better in III1. Nine patients from two additional institutions were included in a special study of Stage III disease. This included 22 children in III1 and 11 children in III2. Although the children with Stage B (systemic symptoms) disease were concentrated in III2, none of the measured difference between these two groups were significant. No fatal postsplenectomy sepsis has been noted since the use of pneumococcal vaccine and prophylactic penicillin became standard.

Abdomen↗
PubMed1982

Neutrophilic phagocytosis in autoimmune thrombocytopenia purpura.

In vivo neutrophil phagocytosis was demonstrated by transmission electron microscopy (TEM) in the peripheral blood of two half-sibs with hereditary thrombocytopenia. These sibs have had a lifetime documented history of thrombocytopenia. Light microscopy morphology and histochemistry studies of blood and marrow were normal, similar studies of blood from available members of the kinship were also normal. Scanning electron microscopy (SEM) of platelets from each member of the kinship showed normal dendritic and spreading formation. In the TEM thin sections of platelet buffy coats, neutrophil ingestion of platelets was common and all stages of the phagocytic process were noted--from platelet-neutrophil intimacy to the formation of myelin bodies in phagosomes. The clinical courses over a 10-year period were mild, requiring rare therapeutic interventions. The chronic thrombocytopenia, lengthy mild course, modestly elevated platelet-associated immune globulin, normal aggregation and survival studies, and autoimmune neutrophil reaction to platelets allowed classification of these patients as hereditary thrombocytopenia purpuras.

Adult↗
PubMed1982

Pneumococcal polysaccharide immunization of children with sickle cell disease. I. Clinical reactions to immunization and relationship to preimmunization antibody.

Vaccine reaction data were obtained from 154 patients with sickle cell disease immunized with tetradecavalent pneumococcal polysaccharide vaccine. There was a high rate (70%) of mild reactions, primarily at the site of injection. Fever over 100 degrees F was uncommon and precipitation of symptoms similar to sickling crisis was rare. Development of local reactions was associated with the level of preimmunization pneumococcal antibody titer.

Anemia, Sickle Cell↗
PubMed1982

Pneumococcal polysaccharide immunization of children with sickle cell disease. II. Serologic response and pneumococcal disease following immunization.

One-hundred seventy-four children with sickle cell disease (SCD) were immunized with a single dose of tetradecavalent pneumococcal vaccine. Preimmunization and postimmunization antibody against 13 of the 14 pneumococcal capsular antigens was measured by indirect hemagglutination (IHA). The ability of each antigen to stimulate antibody following immunization was characterized by one of three types of responses: (1) poor antibody response regardless of the age at immunization (capsular types 6A, 14, and 19F); (2) improving antibody response with advancing age at immunization (capsular types 1, 4, 9N, 12F, 18C, and 23F); and (3) good antibody response regardless of age at immunization (capsular types 2, 3, 7F, and 8). An increase in antibody following immunization was significantly correlated (P less than 0.0005) with an increasing level of preimmunization antibody titer for all 13 antigens. Through the first 24 months of study, two episodes of pneumococcal sepsis caused by group 23 pneumococci were documented in two children immunized prior to 24 months of age (incidence rate, 4.40/100 patient-years in children less than 5 years of age), and one additional episode caused by a group 23 pneumococcus occurred in a 5 7/12-year-old child (incidence rate, 0.66/100 patient-years in children greater than 5 years of age). These observations suggest that anamnestic immune response significantly contributed to the enhanced antibody response observed in older children and adults. Only modest vaccine efficacy may be expected among children with SCD who receive a single dose of pneumococcal vaccine.

Adolescent↗
PubMed1981

Pneumococcal septicemia in children with sickle cell anemia. Changing trend of survival.

Streptococcus pneumoniae infection has been the predominant cause of death among children with sickle cell anemia (SS). We report our observed change in the pattern of progression of septicemia to meningitis and death in nonimmunized SS children who were not receiving prophylactic penicillin in the face of a persistently high incidence of pneumococcal disease. Of 233 SS children less than ages 6 years observed for 781 person-years, the overall incidence rate of pneumococcal septicemia was 5.9 episodes per 100 person-years. Prior to July 1972, of 23 children who had pneumococcal septicemia, eight (35%) died and meningitis developed in 15 (65%), whereas since July 1972, 11 children have had pneumococcal septicemia, but no children died and meningitis developed in only two (18%). This decrease in major morbidity is attributed to the establishment of a clinical program that provides close medical supervision of the SS child with fever and the rapid institution of parenteral antibiotic therapy.

Anemia, Sickle Cell↗
PubMed1981

Newborn diagnosis of abnormal hemoglobins from a large municipal hospital in Los Angeles.

Cord blood samples from 29,611 infants born in Los Angeles over a 71/2 year period were examined for hemoglobinopathies. Among 4,134 Black newborns, the frequency of sickle cell anemia (SS) was 0.3 per cent, of sickle cell trait (AS) 8 per cent, and of Hb-C trait (AC) 2 per cent. Of 17,781 Spanish surnamed (Mexican) newborns, 0.5 per cent had sickle cell trait, and 0.1 per cent had Hb-C trait. Of the 5,541 Caucasian infants, 0.7 per cent had sickle cell trait, and 0.15 per cent had Hb-C trait. Twenty-three Black children with major hemoglobinopathies included 16 with sickle cell anemia, two with hemoglobin C disease (CC), and five with SC disease.

Anemia, Sickle Cell↗
PubMed1981

The imbalance of chain synthesis in hemoglobin F.

The synthesis of Hb F has been found to be unbalanced in a number of conditions, including homozygous HPFH, sickle-cell anemia, and normal term cord bloods. In this study, the counts from the pre-gamma and pre-alpha zones of the chain separation chromatogram are considered to be modified gamma and alpha chains, respectively, and are included in calculating the gamm/alpha ratios for cord blood and sickle-cell blood. The gamma chain is labeled about 52% as efficiently as the alpha chain in reticulocytes. It is possible that nu chain synthesis is balanced in the bone marrow, but subsequently becomes unbalanced in the reticulocyte.

Anemia, Sickle Cell↗
PubMed1980

Positive Coombs test in Hodgkin's disease: significance and implications.

To clarify the clinicopathologic characteristics of Coombs' positivity in Hodgkin's disease, the records of 71 cases were reviewed. The direct Coombs test was positive in seven. Mean age of the seven was 22 yr (range 11-33). All were males. All had extensive disease (pathologic stage III or IV) and six had systemic (B) symptoms. Four had mixed cellularity; three had nodular sclerosis. The positive Coombs test was detected at original diagnosis in three and at time of relapse in four. Although all were anemic, only three had evidence of overt hemolysis. The antibody responsible for Coombs positivity was characterized in three and fulfilled the criteria for IgG anti-It. The presence of a positive direct Coombs test in the patient with Hodgkin's disease suggests active and advanced disease. The presence of IgG anti-It may represent a unique antibody in the Coombs-positive hemolytic anemia associated with Hodgkin's disease.

Adolescent↗
PubMed1979

Childhood leukemia and lymphoma: correlation of clinical features with immunological and morphological studies.

Malignant cells from 49 children with lymphoid neoplasms other than Hodgkin disease were evaluated by surface marker and morphologic studies. We classified the patients into three groups: 36 patients (74%) with acute lymphocytic leukemia; 7 (14%) classified as convoluted lymphocytic lymphoma/leukemia; and 6 (12%) with small noncleaved follicular center cell lymphoma/leukemia. Diffuse marrow involvement was present at diagnosis in some patients in the latter two groups, but their clinical course was not characteristic of the patients with acute lymphocytic leukemia. Male predominance, poor prognosis, and high incidence of central nervous system disease characterized patients in the convoluted lymphocytic and follicular center cell lymphoma/leukemia groups. Clinical presentation in these two groups differed. Proliferations of convoluted lymphocytes were associated with mediastinal masses and proliferations of follicular center cells with intraabdominal tumors. The high incidence of CNS disease in children with neoplasms of convoluted lymphocytes and follicular center cells suggests that these processes have a predilection for the CNS and that patients with them may benefit from CNS prophylaxis.

Adolescent↗
PubMed1979

Hemoglobin Sunshine Seth - alpha 2 (94 (G1) Asp replaced by His) beta 2.

Hemoglobin Sunshine Seth in which a histidyl is substituted for an aspartyl residue at position 94 of the alpha chain was detected at birth in a Caucasian male infant during cord blood screening and is present also in the mother and a male sibling. Although the substitution is in the alpha 1 beta 2 contact, it is without obvious deleterious effect on the hematological parameters or the health of the affected individuals.

Amino Acids↗