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Biomedical subjects

T L Simon

Publications and source records attributed to T L Simon.

At least 19 recordsLinked to original sources
PubMed1992

Investigation of the effect of long-term whole blood donation on immunologic parameters.

Few studies addressing possible immune sequelae of long-term whole blood donation have been published. The purpose of this study was to determine if there were any differences in lymphocyte subsets, monocyte and neutrophil receptors, and antigens important to host defense in committed whole blood donors and in nondonor controls. Blood samples were obtained from 27 whole blood donors who had been donating on a regular basis for at least 4 years and from 21 nondonor controls. A panel of single- and dual-labeled monoclonal antibodies was used to characterize peripheral white cells, and then the cells were analyzed by flow cytometry. Lymphocyte subsets included T (CD3) cells, helper T (CD4) cells, suppressor T (CD8) cells, B (CD19) cells, natural killer (NK) (CD56) cells, and subpopulations of T cells defined by the coexpression of markers for CD3/HLA-DR, CD3/CD56, and CD8/CD11b. Monocyte and neutrophil analysis included quantitation of receptors for C5a, formyl-met-leu-phe, and C3bi (CR3). Monocytes were also analyzed for expression of HLA-DR and CD14 antigens. No significant differences were observed in the whole blood donors and nondonor controls for any of these factors used to assess immunologic status, except for an increase in C3bi receptors on both neutrophils and monocytes from whole blood donors. These findings indicate that the lymphocyte parameters analyzed in this study are unaltered by long-term whole blood donation. Further research is necessary to determine the significance of complement receptor upregulation in whole blood donors and to identify any changes in the functional characteristics of peripheral white cells from whole blood donors.

Blood Donors↗
PubMed1992

Prediction of iron absorption based on iron status of female blood donors.

Iron stores were assessed in 27 postmenopausal healthy women who donated five units of blood (approximately 485 mL/unit) over approximately 1 y. The mean (+/- SD) age was 67.7 +/- 4.0 y and the average time between successive blood donations was approximately 10 wk (range 8-30 wk). Steady-state iron stores at entrance were 10.59 +/- 3.88 mg/kg body wt (mean +/- SD) and declined to 1.03 +/- 3.20 mg/kg by the fifth donation. Determination of iron stores was based on biochemical measures of iron status at each donation. Iron intakes were 23.3 +/- 10.1 mg/d. From these data we developed equations that can be used to predict the frequency at which healthy postmenopausal women can donate blood without becoming iron deficient. The ability of elderly women to become successful blood donors depends primarily on initial iron stores, iron intake, and frequency of donation. Women with low steady-state iron stores may be able to donate only two times per year without becoming iron deficient.

Absorption↗
PubMed1992

Evolution in indications for blood component transfusion.

Indications for blood components are changing but continue to be based on a combination of clinical assessment and laboratory data. In the perioperative setting, some decisions must be made before laboratory data are available. To prevent the inappropriate usage of blood components, prophylactic or expectant treatment should be limited. In red cell transfusion, physiologic indices of oxygen utilization may soon supplement hemoglobin/hematocrit levels in clinical decision making. Less progress has been made in transfusion for hemostasis. Well-designed clinical studies are needed to answer remaining questions; in the interim, nationally accepted guidelines are available to assist clinicians in their decisions.

Adult↗
PubMed1992

The 1989 Comprehensive Blood Bank Survey of the College of American Pathologists.

The 1989 Comprehensive Blood Bank Survey included four additional samples for a total of eight antibody detection and identification challenges. The remainder of the survey was unchanged from prior years. Performance on the graded portions has remained good, with only occasional "problem" samples. For this survey year, the discrepant results were as follows: (1) a D-positive sample not reaching 95% consensus of D typing due to a strong positive direct antiglobulin test; (2) failure of 7% of extent 3 laboratories to identify anti-K in the presence of anti-c; and (3) continued, but lessened "identification" of anti-E, which was not present. The ungraded samples continued to provide educational challenges, and supplemental questions were used to survey current practices.

Blood Banks↗
PubMed1991

Collection of platelets with a new cell separator and their storage in a citrate-plasticized container.

A new apheresis device using microprocessor control for the collection of a high-purity single-donor platelet concentrate was evaluated, as was the storage of platelets for up to 5 days in a citrate-plasticized polyvinylchloride blood bag. The study was conducted in three phases: collection of platelets for in vitro studies and determination of donor safety; autologous transfusion of platelets in healthy volunteers; and transfusion of platelets in patients requiring platelet transfusion therapy. Donors had mild hypocalcemia and minimal changes in blood counts except for a platelet count reduction from 288 +/- 50 x 10(3) (288 +/- 50 x 10(9)/L) to 217 +/- 43 x 10(3) per microL (217 +/- 43 x 10(9)/L). A mean of 3.36 +/- 1.24 x 10(11) platelets was collected in the mean volume of 214 mL with red cell and white cell contamination in the range of 10(7). Morphology and aggregation were as described previously in stored platelets. Platelet survival data in eight subjects showed a mean recovery of 61 +/- 11 percent and mean survival of 5.03 +/- 1.07 days by a weighted-mean model. Patients transfused with platelets had mean increments of 23,000 immediately and of 8000 at 24 hours; corrected count increments were 6000 at 1 hour and 4000 at 24 hours. The platelets were successful in providing hemostasis to these patients. Clinically useful 5-day-stored platelets are obtained by using this apheresis technology with a functionally closed system and a citrate-plasticized blood bag.

Blood Component Removal↗
PubMed1991

A prospective study of blood donations in healthy elderly persons.

Iron stores were observed in 57 healthy elderly volunteers, between 63 and 77 years of age, who donated 5 units of blood over approximately 1 year. An equal number of nondonors who contributed approximately 7 mL of blood at each visit for iron status measurements only were seen at the same frequency as the donor population. At entrance to the study, iron stores in women and men averaged 724 and 875 mg, respectively. After five donations, mean iron stores dropped to 67 mg in women (n = 27) and 362 mg in men (n = 30); four women (15%) became iron deficient, while two (7%) developed iron deficiency anemia. Three men (10%) developed iron deficiency, but none were found to be anemic. Mean intakes of iron were 23.3 and 22.5 mg per day, respectively, for women and men. Iron intakes were adequate to meet iron requirements of nondonors, but they were not sufficient to halt the steady decrease in iron stores among the donor population, in whom iron absorption increased from approximately 5 percent at entrance to 14 percent at the time of the fifth donation. In summary, healthy elderly persons may contribute to the national blood resource; however, donations should probably be limited to less than five per year or donors should regularly take an iron supplement to preserve reasonable amounts of iron reserves.

Absorption↗
PubMed1991

Characteristics of elderly blood donors.

The aging of our society will result in an increased demand for blood components, but it also has the potential to produce a large group of blood donors, the elderly. To study the effects of regular donation by older persons, a randomized, controlled trial is being conducted among 244 healthy, elderly volunteers. This report focuses on the efficacy of the recruiting efforts for that study and describes the resultant population in terms of their demographics, medical status, and donation safety. Of 325 potential subjects, 18 percent were disqualified and 7 percent refused entry into the study. After medical evaluation, only 2 persons were disqualified for conditions not detected by the usual blood services screening protocols. The resultant elderly donor population (n = 244) was well-educated, middle-income, and, for the most part, married. The group reported more past and present medical conditions, past surgical procedures, and current medications than would be expected in a younger donor group. Reactions to donation were infrequent and mild. With current screening and donation procedures, blood donation by the elderly appears to be safe and practical.

Aged↗
PubMed1990

The 1988 comprehensive blood bank survey of the College of American Pathologists.

An average of 2211 laboratories reported results in this comprehensive blood bank survey. In general, the participant performance remains strong in ABO and D typing, unexpected antibody detection and identification, crossmatching, and antigen identification. However, certain samples achieved less than the usual performance levels. In one sample, anti-C, which was not present, was reported by many participants. In a third sample, only 90% of the participants correctly recorded that no antibody was detectable. Two cross-match challenges did not reach the required participant consensus for grading purposes. The ungraded samples and the supplementary questions provide mock clinical situations and are used to determine current practices and procedures in transfusion medicine. The results of these studies and the participant responses are included.

Blood Banks↗
PubMed1989

The issues in autologous transfusion.

Autologous transfusion should be recognized by patients and physicians as an important measure to provide safer transfusion therapy. This should be suggested to patients in general good health (who are not obviously frail) who have no significant medical problems and no likelihood of severe reaction, who can take iron supplements, and who have at least a 10% chance of using blood during surgery or are having surgery in which the average use is one or more units. Such patients should receive iron supplementation beginning 1 week before the first autologous donation, and should donate one to five units on a weekly basis, but no more frequently than every 72 hours, with their last unit donated 72 hours before surgery. Elderly individuals may donate if the risk of donor reaction seems low. In children and adults, the amount of blood removed should be reduced in proportion to the blood volume if the individual does not meet the standard weight of 50 kg for a 450-mL donation. "Fail-safe" identification systems should be used; these will insure that the correct donor/patient receives the transfusion. Processing of the units is preferred but still optional. Use of these units as homologous units should not be done unless the donor has a hematocrit level acceptable to an autologous donor, meets all the criteria for recipient safety, the unit is processed and negative for all viral markers, and the donor has recently (eg, within 3 years) participated in the volunteer donor program. The unit should be transfused to the patient in situations in which homologous blood would be indicated. Safeguards to prevent volume overload are needed when the unit is stored as whole blood. Future research objectives should include the use of recombinant erythropoietin to prevent donation-induced anemia, delineation of medical conditions which should contraindicate the donation, and determination of the real costs involved in autologous transfusion. Education of the general public, patients, and physicians about the desirability of autologous transfusion should proceed. Third-party carriers also need to be educated about the cost implications and the need to pay for this activity. However, such education should also stress that autologous units will only cover planned, elective surgery and that major blood needs for emergency surgery, trauma, and chronic transfusion will still need to be met by homologous blood from altruistic community blood donors.

Anemia↗
PubMed1988

Posttransfusion purpura associated with alloantibody specific for the platelet antigen, Pen(a).

Posttransfusion purpura (PTP) and severe thrombocytopenia occurred 9 days after transfusion of red blood cells to a 48-year-old, multiparous Navajo woman. The platelet count rose to hemostatic levels after treatment with prednisone and three plasma exchange transfusions. Serologic studies showed that the patient's serum contained the potent antibody reactive with platelets from nearly all normal subjects, but nonreactive with autologous platelets obtained after recovery. This antibody was found to be specific for a high-frequency, platelet-specific antigen, designated Pen(a),implicated previously as an immunogen in neonatal alloimmune thrombocytopenic purpura. An exchange of serum showed that Pena is identical with an alloantigen designated Yuk(b) by Japanese workers. We conclude that PTP can occur in association with alloimmunization against Pen(a) (Yuk(b).

Antibody Specificity↗
PubMed1979

Hemostasis in massively transfused trauma patients.

Twenty-seven patients requiring massive transfusions were studied prospectively to determine whether administration of stored, modified whole blood induced a primary disorder of hemostasis evidenced by generalized microvascular oozing. Platelet counts fell in proportion to the number of units of blood transfused. In contrast, the levels of factors V and VIII correlated poorly with the units of blood transfused, 85% of the total variation in the levels being due to influences other than transfused blood. Levels of all other clotting factors were unrelated to the number of units of blood given. Eight patients developed abnormal bleeding. The cause appeared to be dilutional thrombocytopenia in five patients, and DIC in three. In six of the eight, bleeding was controlled with platelet concentrates alone. Two patients were given cryoprecipitate also. The most useful laboratory test for predicting abnormal bleeding was the platelet count. Fibrinogen levels should be followed as an aid in the diagnosis of DIC. The BT, PT, and PTT were not helpful in assessing the cause of bleeding, unless they were greater than 1.5 times the control value. We recommend that any patient receiving massive transfusions who develops diffuse microvascular bleeding be given platelet concentrates. Platelet counts as high as 100,000 may be required to control bleeding from surgical wounds. It is not necessary to supplement transfusions of stored, modified whole blood with fresh blood or fresh frozen plasma.

Adolescent↗
PubMed1978

Heparin pharmacokinetics: increased requirements in pulmonary embolism.

Heparin disappearance after injection and plasma levels during continuous infusion were studied in normal subjects and patients with thrombophlebitis, pulmonary embolism, renal failure, and liver failure. Heparin removal in normal subjects after 75 u/kg was nearly linear with a clearance of 0.64 ml/min/kg, SD +/- 0.11. Clearance varied inversely with dose. Heparin clearance in pulmonary embolism (0.80 ml/min/kg +/- 0.23) was significantly accelerated compared both to normals (P less than 0.005) and to thrombophlebitis patients (0.55 ml/min/kg +/- 0.19, P less than 0.01); the disappearance was more curvilinear in thrombophlebitis and pulmonary embolism than in normal subjects (P less than 0.025). Continuous infusion heparin requirements were greater in pulmonary embolism than in thrombophlebitis, in accordance with pharmacokinetic predictions. The pattern and rate of disappearance in renal disease was similar to normal subjects; in liver disease clearance was accelerated (0.86 ml/min/kg +/- 0.28) and disappearance curvilinear. Because of accelerated clearance, the initial dose of heparin in pulmonary embolism should be greater (25 u/kg/h) than in thrombophlebitis (10-15 u/kg/h). Variability within patient groups necessitates some laboratory control of dosage.

Adult↗
PubMed1978

Multiple plasmacytomas with thoracic and biliary involvement.

The course of a patient who had nonsecretory multiple myeloma was characterized by extraosseous plasmacytomas that were initially limited to pleural lesions with effusion and subcutaneous masses. Subsequently, we noted the development of obstructive jaundice caused by a mass at the head of the pancreas, which was diagnosed by abdominal ultrasound and responded to radiation therapy, and bilateral pulmonary nodules, which were visualized by fiberoptic bronchoscopy. Forceps biopsy of an endobronchial lesion showed plasmacytoma similar in histologic features to her original osseous lesions. The pulmonary nodules responded to cyclophosphamide and prednisone. During her course, she had three forms of intrathoracic myeloma: rib lesions extending into pulmonary tissue, pleural disease, and multiple endobronchial masses. The biliary and pulmonary manifestations of plasmacytomas are rarely seen. Diagnosis by noninvasive procedures and rapid response to conservative therapy were important in this patient's care.

Aged↗
PubMed1977

The clinical features of submassive and massive pulmonary emboli.

Clinical findings in 167 patients with angiographically established pulmonary emboli were analyzed in detail. The clinical symptoms and physical findings in this group were compared with the findings in 160 patients (diagnosis established by angiography) from an earlier similar study. The observations from this, the largest known group of patients with documented pulmonary emboli that has been studied and reported on, revealed that many of the "classic signs and symptoms" occurred infrequently. Most patients in this study had prognostic value. The data from this study demonstrate that no clinical findings are specific for the diagnosis of pulmonary emboli, but the absence of isolated frequently occurring signs and symptoms should mitigate against the presence of pulmonary emboli.

Angiography↗