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Biomedical subjects

G Ramsey

Publications and source records attributed to G Ramsey.

At least 19 recordsLinked to original sources
PubMed2001

CD34(+) cell collection efficiency does not correlate with the pre-leukapheresis hematocrit.

One hundred and seventy-seven large-volume leukapheresis procedures performed on 91 patients over a 15 month period were reviewed to see if the pre-apheresis hematocrit (Hct) affected the CD34(+) cell collection efficiency (CE) of the Fenwal CS 3000 Plus cell separator. The Hct was 0.174-0.461 (median 0.317), and the peripheral blood CD34(+) cell count 2-2487 per microl (median 21). The total CD34(+) cell quantity collected was 3.0-2677.2 x 10(6) (median 113.0). Based on the number of CD34(+)cells contained in the blood volume processed (23.3-37303.2 x 10(6); median 318.0), the CE was 1.7-87.5% (median 30.3). No correlation was found between the Hct and CE (r(2) = 0.0034; P = 0.44) or the total CD34(+) cell quantity collected (r2 = 0.0040; P = 0.40). CEs for Hct <0.25 (median CE 36%), Hct 0.25-0.299 (median CE 30%) and Hct 0.30 (median CE 30%) were comparable. As expected, highly significant correlations were seen between the CD34(+) cell quantities collected and quantities processed (r2 = 0.59; P < 10(-6)) as well as the peripheral blood CD34(+) cell counts (r2= 0.60; P < 10(-6)). We conclude that the minimum acceptable Hct or hemoglobin level for leukapheresis should be dictated by clinical circumstances because it does not affect stem cell collection.

Antigens, CD34↗
PubMed2000

Decision-making capacity to execute a health care proxy: development and testing of guidelines.

OBJECTIVE: To evaluate the reliability and validity of guidelines to determine the capacity of nursing home residents to execute a health care proxy (HCP). DESIGN: A cross-sectional study. SETTING: A 750-bed not-for-profit nursing home located in New York City. PARTICIPANTS: A random sample of 200 nursing home residents: average age, 87; 99% white; 83% female; average length of stay, 3.05 years; mean Mini-Mental State Exam (MMSE) score, 15.9. MEASUREMENTS: Demographic characteristics (Minimum Data Set (MDS)); function and cognitive status (Institutional Comprehensive Assessment and Referral Evaluation (INCARE)); Reisberg Dementia Staging; MMSE; Minimum Data Set-Cognitive Performance Scale (MDS-COGS)); an investigator-developed measure of a nursing home resident's capacity to execute a health care proxy (Health Care Proxy (HCP) Guidelines.) RESULTS: The internal consistency of the decision-making scales in the HCP Guidelines, paraphrased recall and recognition, reached acceptable levels, alphas of .85 and .73, respectively. Interrater reliability estimates were .92 and .94, respectively, for the recall and recognition scales; test-retest reliability estimates were .83 and .90. The discriminant validity of these scales is promising. For example, the MMSE correlation was .51 with the Recall scale and .57 with the Recognition scale. Of residents with severe cognitive impairment (MMSE < 10), 71% completed 50% or more of the scaled items in the HCP guidelines and 95% consistently named a proxy. CONCLUSIONS: Seventy-three percent of testable residents, approximately three-quarters of whom were cognitively impaired, evidenced sufficient capacity to execute an HCP. Of residents with severe cognitive impairment, the HCP guidelines are potentially useful in identifying those with the capacity to execute a HCP. The guidelines are more predictive than the MMSE in identifying residents able to execute a HCP.

Activities of Daily Living↗
PubMed1999

Blood component recalls in the United States.

BACKGROUND: United States blood suppliers are required to recall marketed blood components later found to be in violation of Food and Drug Administration (FDA) regulations for safety, purity, and potency. Many recalled units have already been transfused. Analysis of the frequency and nature of blood component recalls would be useful for blood suppliers, transfusion services, and physicians. STUDY DESIGN AND METHODS: Each blood component recall in the weekly FDA Enforcement Report from 1990 through 1997 was examined for the number of units, recall reason, and hazard class. Units for manufacturing were excluded. RESULTS: In 8 years, an estimated 241,800 blood components were recalled, or approximately 1 in 700 units available to US hospitals. Eighty-eight percent of recalled units were in 22 large recalls of over 1000 units each. The most common reasons were incorrect testing for syphilis (57% of units) or viral markers (19%), reactive or previously reactive donor viral markers (6-11%), and inadequate donor-history screening (4%). Twelve units were in the FDA's highest hazard Class I, 24 percent were in Class II, and 76 percent were in Class III. Over 43,900 units had HIV-related problems, but only 3 units involved HIV transmission. Large recalls have declined since peaking in 1995, but units in small recalls increased 116 percent in 1997 over the previous 7-year average. CONCLUSIONS: Although high-risk recalls are rare, many blood component recalls pose medical concerns for physicians and patients. The recent decline in large recalls may be due to increased FDA oversight, stricter accreditation standards for quality improvement, and more centralized donor testing in large specialized laboratories. However, smaller recalls, which involve nearly all blood suppliers, were sharply higher in 1997.

Blood Component Transfusion↗
PubMed1998

Hematopoietic growth factors and transfusion medicine.

At least 20 different hematopoietic drugs (see Table 1) are currently under investigation. These most likely will impact on all aspects of transfusion therapy. Which agents to use and in what combinations will be the subject of scrutiny for many years to come as scientists try to recreate and enhance the process of hematopoiesis. Perhaps someday blood cells and hematopoietic progenitor cells can be manufactured for therapy with genetically selected phenotypes to avoid immune destruction and rejection. If this comes to pass, blood donations as we know them today, as a valuable adjunct to medical care, will fade into history, supplanted by the use of hematopoietic growth factors.

Blood Component Transfusion↗
PubMed1997

Implementation of the Patient Self-Determination Act (PSDA) in nursing homes in New York City.

OBJECTIVE: To examine implementation of the Patient Self Determination Act (PSDA), verbal directives, procedures for determination of resident' decision-making capacity, and role of ethics committees in nursing homes in New York City. DESIGN: Telephone survey. PARTICIPANTS: Social workers in 109 (69%) nursing homes in New York City. MEASUREMENT: An 80-item instrument addressing: (1) social worker knowledge of the PSDA; (2) informing residents about advance directives (living wills and durable power of attorney for health care [health care proxies]); (3) determination of decision-making capacity to be informed about advance directives; (4) estimates of advance directives executed; (5) perceptions of PSDA effect; (6) ethics committees; (7) follow-up and documentation; and (8) staff and community education. MAIN RESULTS: Virtually all social workers in nursing homes stated that they made what they perceived to be a "serious effort" to inform residents about advance directives and to have residents execute directives (preferentially a health care proxy). More residents were thought to have executed a directive pursuant to the PSDA law than before the Act went into effect. Social workers in most homes informed residents about directives through face-to-face discussions. Most homes, however, did not inform residents who were thought to lack decision-making capacity about their right to execute a directive. Only 37% of homes had written procedures to determine a resident's decision-making capacity to be informed about directives; most homes relied on physician and social work assessments. Voluntary homes differed significantly from proprietary homes in that they were larger, more likely to have an ethics committee, and more aggressive in their implementation of the PSDA. Forty-five percent of homes with an ethics committee had written procedures for determination of resident decision-making capacity compared with 26% of homes without a committee. Overall, 24% of residents were thought to have executed an advance directive. The number of directives per bed did not vary significantly by facility size, ownership, religious affiliation, or whether they did or did not have an ethics committee. CONCLUSIONS: The fact that social workers in nursing homes speak with most residents about advance directives has the potential to improve resident understanding around end of life decisions. The practice of not informing residents about advance directives when they are perceived to lack decision-making capacity is problematic given that most homes have no clear procedures for determining residents' cognitive capacity to execute a directive. There is a need to replicate the benefits achieved by homes with ethics committees in implementing the PSDA in other homes.

Advance Directives↗
PubMed1995

Multiple or uncommon red cell alloantibodies in women: association with autoimmune disease.

BACKGROUND: Patients with multiple or uncommon red cell (RBC) alloantibodies require special efforts in the blood bank. This study investigated whether such persons had other immune-related conditions that might help to explain or predict their propensity for RBC antibody formation. STUDY DESIGN AND METHODS: Charts were retrospectively reviewed of 29 men and 83 women with multiple (> or = 3) RBC antibodies of potential clinical significance, uncommon RBC antibodies (anti-e, -Kpb, -Jkb, -Fyb, -S, -U, -Yta, -Dib, -Ata), or both. The clinical features in 43 women with multiple antibodies were compared to those in two equal-sized control cohorts of women matched for transfusion-related diagnoses, but having either one RBC antibody or none. RESULTS: Women with uncommon RBC antibodies had a 33-percent (18/54) prevalence of autoimmune disease. Twenty-eight percent of the 43 women with multiple antibodies had autoimmune disease, compared to 14 percent of women in the cohort with one RBC antibody (p = 0.09) and 7 percent of those in the cohort without RBC antibodies (p = 0.01). Only one of the 29 men had autoimmune disease. CONCLUSION: Autoimmune disease is a common underlying factor in women who make multiple or uncommon RBC alloantibodies of potential clinical significance.

Autoimmune Diseases↗
PubMed1995

Clinical significance of anti-At(a).

Ata is a high-frequency red blood cell (RBC) antigen. Anti-At(a) has been reported in rare At(a-) black subjects. We report two cases of anti-At(a). A clinically significant anti-At(a) was found in a 26-year-old black woman with systemic lupus erythematosus. The patient had a transfusion reaction with chills and nausea during a RBC survival study, and 95% of the radiolabeled At(a+) RBCs were destroyed within 3 h. A concurrently performed monocyte monolayer assay was strongly reactive. Anti-At(a) thus can cause rapid hemolysis of transfused RBCs, but At(a-) donor units are extremely scarce in rare donor registries. A second patient at our hospital had anti-At(a) which did not affect her newborn. She also had autoimmune disease, insulin-dependent diabetes mellitus.

Adult↗
PubMed1995

Variation in the use of red blood cell transfusions. A study of four common medical and surgical conditions.

This study assessed variation in red cell transfusion practice among adult patients hospitalized with ulcer disease (ULCER), and those undergoing coronary artery bypass grafting (CABG), hip surgery (HIP), or total knee replacement (KNEE). The study design was a retrospective analysis of the 1989 MedisGroups Hospital Comparative Database, and the participants were adult patients presenting for their first admission with ULCER (N = 4,664), CABG (N = 6,812), HIP (N = 4,131) or KNEE (N = 3,042) in the MedisGroups Hospital Comparative Database. Outcome measures were whether a patient was transfused, and the number of units transfused. Logistic regression was used to analyze the decision to transfuse, and linear regression to analyze the number of units transfused. In these analyses, patient characteristics, hospital characteristics, and unique hospital identity were used as independent variables. The percentage of patients transfused was ULCER 50%, CABG 81%, HIP 69%, and KNEE 51%. The range among hospitals in the percentage of patients transfused was ULCER 11% to 76%, CABG 51% to 100%, HIP 36% to 95%, and KNEE 9% to 97%. When only patient characteristics were entered in the linear regression analyses, the R2 values were ULCER 0.33, CABG 0.11, HIP 0.11, and KNEE 0.07. When hospital was added, the R2 increased to ULCER 0.38, CABG 0.29, HIP 0.19, and KNEE 0.20 (P < 0.0001 for the change for all analyses). The results of the logistic regression analyses of the probability of transfusion were similar. There is substantial interhospital variation in the proportion of patients transfused and number of units transfused in the four conditions studied. Patient demographic and clinical characteristics explain a substantial proportion of the variation in transfusion practices for ulcer patients, but little of the variation in the three surgical conditions.

Adult↗
PubMed1994

Optimal electrode placements for adequate spatial sampling of auditory evoked potentials.

When evoked responses are used in clinical practice and research the measures that are most commonly considered are the latencies and amplitudes of EP components as measured at a single electrode site. Our recent studies have shown that multichannel recordings yield measures such as potential field asymmetry that may be as important as component latency and amplitude. The purpose of this short technical note is to suggest that electrode placement is critical for demonstrating interesting features of the potential field topography, specifically, bilateral, homologous generator sites. The cortical imaging technique (CIT) was used to analyze the averaged responses for a group of thirty normal young adults to a repeated tone and a random oddball tone. Recordings were obtained at 28 scalp recording sites which included 20 placements from the 10-20 system and eight additional sites. Simulated cortical maps were derived for four components, the N1 frequent response and the N2a, P3, and N3, rare minus frequent responses for three different electrode arrays. These arrangements included the full 28-channel array, a 20-channel array that excluded eight additional central sites, and a 20-channel array that included the eight additional sites and excluded peripheral sites. This study demonstrates that for these auditory paradigms, the placement of the electrodes is critically important for discriminating important features of the potential fields.

Acoustic Stimulation↗
PubMed1994

Long-term follow-up testing of red cell alloantibodies.

BACKGROUND: In previous studies, 29 to 34 percent of potentially hemolytic red cell antibodies were not detected after short-term follow-up. STUDY DESIGN AND METHODS: To examine long-term detection, records were reviewed for 44 consecutive patients who were tested more than 5 years after their potentially hemolytic red cell antibodies were first identified in this hospital. RESULTS: After 5 to 10 years, 14 (39%) of 36 Rh, Kell, and Duffy system antibodies were not detected on at least one occasion. Twenty-two other such antibodies were sought again after more than 10 years; 10 (45%) were not detected. When restimulation by pregnancy was excluded, these rates were 42 and 48 percent, respectively. CONCLUSION: Clinically significant red cell antibody formation is probably more common than previously realized, because nearly half of these antibodies are undetected after long-term follow-up.

Blood Group Antigens↗
PubMed1994

Identification of a new white cell antigen.

BACKGROUND: Antibodies to white cell antigens can cause alloimmune neonatal neutropenia, autoimmune neutropenia, and transfusion reactions. CASE REPORT: A full-term male infant developed a skin infection and was found to be neutropenic on his fourth day of life. He had a transient increase in his neutrophil count after treatment with intravenous immunoglobulin, but his neutrophil count was not consistently normal until he was 6 weeks old. Serum from the baby's mother reacted in a granulocyte immunofluorescence assay but not in a granulocyte agglutination assay. The mother's serum was tested in the granulocyte immunofluorescence assay against neutrophils from 103 healthy, unrelated people, and it reacted with cells from 66 percent of those people. The expression of SL correlated weakly with the expression of NA1 (r = 0.23; p = 0.02) and 5a (r = 0.20; p = 0.05) antigens. SL antigen expression on neutrophils was not associated with the expression of NA2, NB1, NB2, NC1, 5b, 9a, or Mart. The expression of SL on neutrophils from members of an extended family was analyzed, and the antigen was found to be inherited in an autosomal-dominant manner. Anti-SL also reacted with T-lymphocytes in a flow cytometry assay but did not react with red cells or platelets. No lymphocytotoxic antibodies were detected in the mother's sera. The anti-SL was tested against neutrophils in an immunoprecipitation and immunoblotting assay, but no molecules were identified. The neutrophil-specific antigens NA are located on Fc gamma receptor III (CD16). To determine if the SL antigen was also located on Fc gamma receptor III, anti-SL was also tested in a monoclonal antibody immobilization of granulocyte antigens assay. Anti-SL did not react with molecules recognized by CD16 monoclonal antibodies. CONCLUSION: A new white cell antigen SL, with a frequency of 66 percent, was identified on neutrophils and T-lymphocytes as a result of the evaluation of a case of neonatal alloimmune neutropenia. The molecule bearing the SL antigen was not identified in immunoblotting, immunoprecipitation, or monoclonal antibody immobilization of granulocyte antigens assays.

Adult↗
PubMed1994

The pathophysiology and organ-specific consequences of severe transfusion reactions.

Transfusion of blood components is usually required in the management of critically ill patients. However, pathologic interactions between blood products and organ function may result from transfusion reactions. Emerging understanding of the mediation and interruption of clinical inflammatory responses is applicable to severe transfusion reactions. The pathophysiology of four types of severe transfusion reactions are reviewed: a) acute hemolysis; b) bacterial contamination of blood components; c) transfusion-related acute lung injury (TRALI); and d) anaphylaxis. Acute hemolytic reactions are often caused by preventable errors in sample or patient identification. Renal toxicity, coagulopathy, and hypotension may result from circulating red cell stroma and immune-complex activation of complement and cytokine secretion. Bacterial contamination of blood components has caused patient sepsis in many cases; platelets stored at 20 degrees to 24 degrees C are of particular concern. Careful blood collection and handling is essential for prevention. TRALI is manifested by acute respiratory distress, which is usually caused by infusion of plasma containing antibodies against the patient's leukocytes. Complement activation and cytokine stimulation cause edema and neutrophil accumulation in the lungs. Anaphylactic reactions may result from patient immunoglobulin (Ig)E antibodies against donor plasma constituents. IgA-deficient patients are at risk for anaphylactic reactions if these patients develop anti-IgA antibodies. Vasoactive or complement-activating factors in a blood product may also cause anaphylactoid reactions in some patients.

Acute Disease↗
PubMed1994

Transfusion therapy in solid organ transplantation.

Numerous transfusion issues arise in the support of solid organ transplantation. ABO and HLA can cause graft rejection immunity or problems in transfusion support. Blood usage has been reduced by the use of erythropoietin in renal failure and aprotinin during liver transplants. Multifactorial coagulopathy during liver transplant surgery continues to be a challenge requiring close monitoring, however. The beneficial effect of transfusions on graft survival has lessened in recent years, but remains an area of active research.

ABO Blood-Group System↗