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Biomedical subjects

R Hoffman

Publications and source records attributed to R Hoffman.

At least 91 records · Page 5Linked to original sources
PubMed1998

Collection, tumor contamination, and engraftment kinetics of highly purified hematopoietic progenitor cells to support high dose therapy in multiple myeloma.

Unfractionated peripheral blood stem cell (PBSC) grafts contain measurable quantities of myeloma cells and are therefore a potential source of relapse posttransplantation. In contrast, fluorescence-activated cell sorting (FACS)-sorted CD34+ Thy1+ Lin- peripheral blood cells are substantially enriched for stem cell activity, yet contain virtually no clonal myeloma cells. A study was performed in patients with symptomatic myeloma, who had received 12 months or less of preceding standard chemotherapy, to evaluate the feasibility of large scale purification of primitive hematopoietic stem cells in order to study engraftment kinetics posttransplantation and the degree of tumor cell contamination of this cell population, based on polymerase chain reaction (PCR) analysis for the patient-specific complementarity-determining region III (CDR III). PBSC were mobilized with high dose cyclophosphamide and granulocyte-macrophage colony-stimulating factor (GM-CSF). A combination of elutriation and chemical lysis was used to deplete PBSC collections of monocytes, granulocytes, erythrocytes, and platelets. Subsequently, CD34+ Thy1+ Lin- progenitor cells were purified with high speed cell sorting. Of the 10 evaluable patients, nine met the required minimum criteria of >/=7.2 x 10(5) cells/kg to support tandem transplants. After high dose melphalan (200 mg/m2) eight engrafted successfully, although granulocyte (absolute neutrophil count [ANC] >0.5 x 10(9)/L, 16 days) and platelet recovery (platelets > 50 x 10(9)/L, 39 days) was substantially delayed when compared with unmanipulated PBSC grafts; one patient required infusion of a reserve graft because of lack of evidence of engraftment by day +28. Three patients proceeded to a second graft with high dose melphalan and total body irradiation; two required infusion of a reserve graft and both died of infectious complications; one showed delayed, but complete, engraftment after this myeloablative regimen. Two of the nine evaluable patients attained a clinical complete remission (CR). The grafts from three patients were tested for tumor contamination and contained no detectable clonal myeloma cells. Larger quantities of purified cells may be required to resolve the problem of delayed engraftment.

Adult↗
PubMed1998

The Smad5 gene is involved in the intracellular signaling pathways that mediate the inhibitory effects of transforming growth factor-beta on human hematopoiesis.

Signals from transforming growth factor-beta (TGF-beta), a bifunctional regulator of the proliferation of hematopoietic progenitor cells, have been recently shown to be transduced by five novel human genes related to a Drosophila gene termed MAD (mothers against the decapentaplegic gene). We showed by reverse transcriptase polymerase chain reaction that the RNA from one homologue gene, Smad5, was present in the immortalized myeloid leukemia cell lines, KG1 and HL60, in bone marrow mononuclear and polymorphonuclear cells, as well as in purified CD34+ bone marrow cells. Therefore, we studied the role of this gene in the regulation of human hematopoiesis by TGF-beta. TGF-beta1 and TGF-beta2 significantly inhibited myeloid, erythroid, megakaryocyte, and multilineage colony formation as assayed in semisolid culture systems. The levels of Smad5 mRNA in CD34+ cells were decreased by antisense but not sense oligonucleotides to Smad5. Preincubation of CD34+ marrow cells with two sense oligonucleotides to Smad5 did not reverse the inhibitory effects of TGF-beta on hematopoietic colony formation. However, preincubation with two antisense oligonucleotides to Smad5 reversed the inhibitory effects of TGF-beta. These data show that the Smad5 gene is involved in the signaling pathway by which TGF-beta inhibits primitive human hematopoietic progenitor cell proliferation and that Smad5 antisense oligonucleotides can interrupt this signal.

Cell Division↗
PubMed1998

Predictors of subjective fatigue among individuals with rheumatoid arthritis.

OBJECTIVE: To examine a range of variables potentially associated with rheumatoid arthritis (RA)-related fatigue and to determine which variables best predict subjective fatigue. METHODS: Measures of fatigue, disease activity, pain, and various psychosocial factors were gathered from 73 individuals with RA. Correlations between fatigue and other variables were examined, and the "best" predictors of fatigue were determined with multiple regression analyses. RESULTS: Many of the variables that were significantly correlated with fatigue had a psychosocial character. Moreover, the "best" predictors of increased fatigue were higher levels of pain, more depressive symptoms, and female sex. Longer symptom duration, less perceived adequacy of social support, and less disease activity were significant predictors of fatigue, over and above the "best" model. CONCLUSION: RA-related fatigue appears to be strongly associated with psychosocial variables, apart from disease activity per se. Correspondingly, treatment of fatigue may be enhanced by interventions that address relevant cognitive and behavioral dimensions.

Aged↗
PubMed1998

Firearm-related injury surveillance in Colorado.

CONTEXT: The Colorado Department of Public Health and Environment uses existing data sources to identify and assess firearm-related deaths and injuries statewide. OBJECTIVE: Implementation and evaluation of a surveillance system for fatal and hospitalized nonfatal firearm-related injuries. DESIGN: Electronic death certificate and hospital discharge data are used to identify firearm-related deaths and injuries. Cases are confirmed and supplemental information is obtained from the Colorado Uniform Crime Report/Supplemental Homicide Report, police investigations, medical records, and newspaper accounts. Electronic data sets are created containing the information manually abstracted from these sources. SETTING: Statewide. PARTICIPANTS: Vital records, Colorado Hospital Association, medical records, Colorado Division of Criminal Justice, police departments. MAIN OUTCOME MEASURES: Surveillance system simplicity, flexibility, sensitivity, and predictive value positive. RESULTS: System-identified cases were compared with deaths and injuries identified from external sources such as hospital trauma registries, emergency department logs, and paramedic trip reports. The surveillance system is flexible, acceptable to reporting agencies, and sensitive, detecting 69% to 77% of firearm-related hospitalizations identified from external sources. The system's predictive value positive is high, with 89% of the potential cases confirmed as actual cases. Although simple in design, the surveillance system requires significant staff time to abstract information and because existing data sources are used, timeliness of the data is often delayed. Additionally, minor injuries (those requiring less than 24 hours or no hospitalization) are not detected. CONCLUSIONS: Despite these limitations, the surveillance system is a valuable resources for information about firearm-related deaths and injuries, and represents an important first step in reducing the number and severity of firearm-related injuries in Colorado.

Adolescent↗
PubMed1998

Adolescent issues in renal treatment.

Everyone who helps to care for a growing and developing child has the potential to impact the future. Families provide the greatest influence and bear the major responsibility, but physicians, nurses, dietitians, social workers, teachers, camp counselors, and others who work with children make a direct contribution toward the development of the child's self image and image of the world around them. At no other time in an individual's life do other people have such awesome power and responsibility. Families and caregivers working together on behalf of a child may be likened to an extended family; their combined efforts are needed to help promote the resilience that children need to cope with serious chronic illness.

Adolescent↗
PubMed1998

Adaptation and evaluation of the Liverpool Seizure Severity Scale and Liverpool Quality of Life battery for American epilepsy patients.

The Liverpool Seizure Severity Scale (LSSS) and the Liverpool Quality of Life (LQOL) battery were developed in Great Britain to assess the severity of seizure symptoms and the impact of epilepsy on patients' quality of life. The scales have been validated on British patients, but have not been validated for use with American patients. The objectives of this study were to adapt the scales to the American population and to evaluate their reliability and validity. After modifications recommended by focus groups with patients and epilepsy specialists, the scales were administered to a sample of 90 epilepsy patients who had experienced seizures within the previous 4 weeks. Comparisons of patients with generalized tonic-clonic seizures (n = 58) and partial seizures (n = 32) revealed significant differences on 9 of the 20 items on the LSSS as well as the total score. None of the six LQOL subscales (negative drug effects, positive drug effects, affect balance, sense of mastery, life fulfilment and impact of epilepsy) distinguished patients with different seizure types but five of the six subscales were significantly correlated with seizure severity. The internal consistency and test-retest reliability were adequate for both the LSSS and LQOL. Finally, five of the six LQOL scales were significantly correlated with independent measures of mental health, physical health and role functioning.

Adult↗
PubMed1998

Adaptation and evaluation of the Liverpool Seizure Severity Scale and Liverpool Quality of Life battery for American epilepsy patients.

The Liverpool Seizure Severity Scale (LSSS) and the Liverpool Quality of Life (LQOL) battery were developed in Great Britain to assess the severity of seizure symptoms and the impact of epilepsy on patients' quality of life. The scales have been validated on British patients, but have not been validated for use with American patients. The objectives of this study were to adapt the scales to the American population and to evaluate their reliability and validity. After modifications recommended by focus groups with patients and epilepsy specialists, the scales were administered to a sample of 90 epilepsy patients who had experienced seizures within the previous 4 weeks. Comparisons of patients with generalized tonic-clonic seizures (n = 58) and partial seizures (n = 32) revealed significant differences on 12 of the 20 items on the LSSS as well as the total score. None of the six LQOL subscales (negative drug effects, positive drug effects, affect balance, sense of mastery, life fulfillment and impact of epilepsy) distinguished patients with different seizure types but five of the six subscales were significantly correlated with seizure severity. The internal consistency and test-retest reliability were adequate for both the LSSS and LQOL. Finally, five of the six LQOL scales were significantly correlated with independent measures of mental health, physical health and role functioning.

Adult↗
PubMed1998

Medical care for haemophilia.

BACKGROUND/OBJECTIVES: Haemophilia is a lifelong bleeding disorder associated with significant morbidity. Because of this for almost 25 years there has been a national network of specialized haemophilia treatment centres (HTCs). Despite this, there is little published information about HTC utilization. We chose to study utilization and satisfaction with care received from the Colorado HTC as compared with that received at other nonspecialized sites. RESEARCH DESIGN: A survey was designed in collaboration between Colorado Department of Public Health and Environment (CDPHE) and the Denver Mountain States Regional Hemophilia Center personnel for telephone administration by CDPHE personnel to all persons with haemophilia (pwh) residing in Colorado in 1994. SUBJECTS: One hundred forty-five persons with haemophilia (77% of those eligible) participated in the survey. RESULTS: The majority of respondents received care from the HTC. Persons less than 21 years of age and those with severe disease were significantly more likely to do so. Satisfaction with care received at the HTC was greater than that received at other sites (P < 0.01). Issues of concern were insurer restricted access to the HTC and the lack of haemophilia knowledge of non-HTC providers. CONCLUSIONS: If HTCs and other specialty centres are to survive in an increasingly managed care environment, in addition to increased patient satisfaction, data documenting improved patient outcome with specialty centre directed care will be necessary to facilitate referral.

Adolescent↗
PubMed1998

Wound fluid from venous leg ulcers degrades plasminogen and reduces plasmin generation by keratinocytes.

Plasminogen, the pro-enzyme of plasmin, aids various processes essential for normal, acute wound healing, such as fibrinolysis and cell migration. We have investigated if plasminogen is available to perform these functions in chronic wounds such as venous leg ulcers. We report that plasminogen is degraded by fluid from venous leg ulcers to a number of fragments, including kringle domains 1-3, an angiostatin-related protein. The enzyme responsible was inhibited by the serine protease inhibitor phenyl-methylsulfonyl fluoride, but was not inhibited by alpha1-anti-trypsin, an inhibitor of neutrophil elastase, by alpha2-anti-plasmin, an inhibitor of plasmin, or by the matrix metalloprotease inhibitor 1,10 phenanthroline. Plasminogen degraded by wound fluid was a weaker substrate than intact plasminogen for plasmin generation by the keratinocyte cell line HaCaT. These results suggest that serine protease activity in leg ulcer fluid degrades plasminogen and support the hypothesis that keratinocyte migration may be impaired in leg ulcers because of a reduced availability of intact plasminogen for plasmin generation.

Angiostatins↗
PubMed1998

Modification of bacterial artificial chromosome clones using Cre recombinase: introduction of selectable markers for expression in eukaryotic cells.

Bacterial artificial chromosome clones (BACs) are widely used at present in human genome physical mapping projects. To extend the utility of these clones for functional genomic studies, we have devised a method to modify BACs using Cre recombinase to introduce a gene cassette into the loxP sequence, which is present in the vector portion of the BAC clone. Cre-mediated integration is site specific and thus maintains the integrity of the genomic insert sequences, while eliminating the steps that are involved in restriction digest-based DNA cloning strategies. The success of this method depends on the use of a DNA construct, RETRObac, which contains the reporter marker green fluorescent protein (GFP) and the selectable marker neomycin phosphotransferase (neo), but does not contain a bacterial origin of replication. BAC clones have been modified successfully using this method and the genomic insert shows no signs of deletions or rearrangements. Transfection efficiencies of the modified BACs into human or murine cell lines ranged from 1% to 6%. After culture in media containing G418 for 3 weeks, approximately 0. 1% of cells previously sorted for GFP expression acquired stable antibiotic resistance. Introduction of a human BAC clone that contains genomic p53 sequences into murine NIH3T3 cells led to expression of human p53 mRNA as determined by RT-PCR, demonstrating that sequences contained on the BAC are expressed. We believe that GFP-neo modified BAC clones will be a valuable resource in efforts to study biological effects of known genes as well as in efforts to clone and analyze new genes and regulatory regions.

Animals↗
PubMed1998

Ex vivo expansion of human hematopoietic stem cells: implications for the modern blood bank.

Pluripotent hematopoietic stem cells (PHSC) are rare cells within the marrow that are capable of self-renewal and differentiation into multiple hematopoietic lineages. Following myeloablative chemotherapy and radiation therapy and marrow transplantation, hematological reconstitution occurs after a period of 2-3 weeks. Recently, a number of laboratories have shown that both early and delayed phases of engraftment are mediated by PHSC within a graft and that engraftment can be accelerated by transplanting greater numbers of PHSC. Increasing efforts have been directed, therefore, towards developing methods to expand PHSC ex vivo. In this report, we describe an endothelial cell-based culture system to which exogenous cytokines are added which appears to permit the ex vivo expansion of PHSC. Refinement of these technologies will potentially have a major impact on the ability of blood banks to improve the quality of hematopoietic stem cell grafts.

Adult↗
PubMed1998

Definition of early progenitors and functional maturation of human natural killer cells: requirements for cytocidal activity.

We examined the in vitro development of human natural killer (NK) cells to define the earliest hematopoietic progenitors which could give rise to NK cells. Our data indicates that NK cells arise from the Thy 1+ subpopulations of CD34+ marrow cells. In cultures with IL2 we generated up to 96.5% NK cells from CD34+ Thy 1+ and in cultures with IL7, cells bearing NK cell surface markers were also observed but were devoid of functional activity. We also addressed the functional integrity of these cultured cells by examining the appearance of granzyme A, serine esterase, Met-ase and perforin and correlating these with lytic activity. Granzyme A mRNA could be detected in IL2-cultured cells and serine esterase activity as well as perforin were also found at the single cell level. Human Met-ase (Hu-Met-1) was not detected at any time of analysis. Granzyme expression occurs early in cells cultured with IL2 but its presence did not correlate with lytic function; CD56+ cells grown in the presence of IL7 express these enzymes and perforin after longer periods of culture, but lack the ability to lyse NK targets.

Adult↗
PubMed1998

Thrombopoietin mobilizes CD34+ cell subsets into peripheral blood and expands multilineage progenitors in bone marrow of cancer patients with normal hematopoiesis.

Thrombopoietin (TPO), the primary regulator of megakaryocytopoiesis, also mediates biologic effects in vitro on hematopoietic cells more primitive than those committed to the megakaryocyte (MK) lineage. To assess the spectrum of hematopoietic effects of recombinant human (rh)TPO in vivo, we evaluated its proliferative effect on bone marrow (BM) progenitor cells, its maturation effect on BM MKs, and its mobilizing effect on peripheral blood (PB) progenitor cells during a phase I clinical laboratory investigation in which rhTPO was administered to cancer patients with normal hematopoiesis. Twelve patients received a single dose of rhTPO (0.3, 0.6, 1.2, or 2.4 microg/kg of body weight) prior to chemotherapy. BM and PB samples from these patients were analyzed 1 to 2 days before (baseline) and 7 days after rhTPO administration. At higher doses (1.2-2.4 microg/kg), rhTPO produced increased concentrations of primitive CD34+Thy-1+Lin-cells (mean 2.1-fold), CD34+mpl+ cells (mean 5.2-fold), CD34+CD41+CD14- promegakaryoblasts (mean 2.9-fold), and myeloerythroid colony-forming cells (mean threefold) in BM. No significant increases in the frequency of BM colony-forming unit (CFU)-MK were observed. Elevated numbers of both immature (2N-8N) and more mature (64N and 128N) CD41+ MKs were detected in BM, with modal ploidy remaining at 16N. Higher doses of rhTPO (1.2-2.4 microg/kg) also induced increased concentrations of CD34+ cell subsets in PB, including both primitive CD34+Thy-1+Lin- (mean 8.8-fold) and MK lineage-committed CD34+CD41+CD14- cells (mean 14.6-fold) as well as various myeloerythroid colony-forming cells (mean 3.6- to 5.5-fold). These results demonstrate that rhTPO given as a single dose not only promotes proliferation and maturation of cells of the MK lineage, but also expands the pool of BM primitive hematopoietic cells. In addition, rhTPO induces mobilization of hematopoietic progenitors into peripheral circulation. The extent to which such multilineage effects on human progenitor cells will contribute to clinical efficacy remains to be determined.

Adolescent↗
PubMed1998

Pinless external fixation. Indications and preliminary results in tibial shaft fractures.

A major drawback of conventional fixator systems is the penetration of the fixator pins into the medullary canal. The pins create a direct link between the medullary cavity and the outer environment. The new AO pinless fixator bypasses this disadvantage by clamping its trocar points onto the outer cortex without penetrating it. Thus, exposure and consequent contamination of the medullary cavity does not occur. The clinical use of this easily manageable fixator with no drilling requirement is for tibial fractures in which the general and local conditions are poor or the infrastructure of the clinic is inadequate for primary internal stabilization or both. All options for a later conversion to internal fixation remain open. For highly unstable tibial shaft fractures, the pinless fixator can be applied as an additional, minimally invasive, external, locked system to increase the stability of intramedullary nail fixation. The pinless external fixator can be combined favorably with the standard AO tubular system and is a valuable addition to the existing fixator systems.

Adolescent↗
PubMed1998

Human megakaryocyte progenitor cells.

Megakaryocytopoiesis is a complex biological process involving a series of cellular events that is initiated with the pluripotent hematopoietic stem cell and eventually results in the biogenesis of platelets shed by mature megakaryocytes (MK). A hierarchy of human MK progenitor cells has been defined by means of studies of in vitro megakaryocytopoiesis. A number of in vitro clonal assays have been established that have aided in the characterization of each of these MK progenitor cells which can be distinguished by their cellular phenotype, physical characteristics, chemosensitivity, kinetics of colony formation, the size of the colonies that each progenitor cell subclass is capable of producing, and the cytokines required to induce such progenitor-cell-derived colony formation. The kinetics of appearance of these various classes of MK colonies derived from MK progenitor cells of differing proliferative capacity are consistent with a sequential developmental relationship between these various cellular subpopulations. The most primitive lineage-restricted MK progenitor cell identified to date is termed the high proliferative potential cell-MK (HPPC-MK). The HPPC-MK can be assayed from fetal but not adult human marrow, and in vitro it forms large unifocal pure MK colonies consisting of more than 300 cells (300 to 1,000). The burst forming unit-megakaryocyte is the most primitive MK progenitor cell that can be assayed from a variety of adult hematopoietic tissues, while the colony forming unit-megakaryocyte is the most differentiated MK progenitor cell still capable of forming pure MK colonies in vitro. Furthermore, a number of multipotent progenitor cells have been identified that are capable of producing colonies composed of multiple hematopoietic lineages of which MKs represent a minority component. A bipotent erythromegakaryocytic progenitor cell in human marrow has been carefully characterized that has the unique ability to form colonies composed exclusively of MKs and erythroblasts. This bipotent progenitor cell has been termed the burst-forming unit erythroid/MK and is indicative of the close linkage between features of the erythroid and megakaryocytic lineages. Recently the ex vivo incubation of CD34+ cells in the presence of a combination of cytokines has resulted in the generation of cell populations enriched for MKs and MK progenitor cells. Such an ex vivo generated product may serve as a source of a new generation of transfusion products capable of supporting thrombocytopenic patients.

Adult↗
PubMed1998

Bone marrow repopulation by human marrow stem cells after long-term expansion culture on a porcine endothelial cell line.

In vitro exposure of murine hematopoietic stem cells (HSCs) to cell cycle-inducing cytokines has been shown to result in a defect in the ability of these cells to engraft. We used a porcine microvascular endothelial cell (PMVEC) line in conjunction with exogenous interleukin (IL)-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), and stem cell factor (SCF) to expand human HSCs that express the CD34 and Thy-1 antigens but lack lineage-associated markers (CD34+Thy-1+Lin- cells). Ex vivo expansion of hematopoietic cells was evaluated in comparison to stromal cell-free, cytokine-supplemented cultures. Cells expressing the CD34+Thy-1+Lin- phenotype were detectable in both culture systems for up to 3 weeks. These cells were reisolated from the cultures and their ability to engraft human fetal bones implanted into SCID mice (SCID-hu bone) was tested. HSCs expanded in PMVEC coculture were consistently capable of competitive marrow repopulation with multilineage (CD19+ B lymphoid, CD33+ myeloid, and CD34+ cells) progeny present 8 weeks postengraftment. In contrast, grafts composed of cells expanded in stroma-free cultures did not lead to multilineage SCID-hu bone repopulation. Proliferation analysis revealed that by 1 week of culture more than 80% of the cells in the PMVEC cocultures expressing the primitive CD34+CD38- phenotype had undergone cell division. Fewer than 1% of the cells that proliferated in the absence of stromal cells remained CD34+CD38-. These data suggest that the proliferation of HSCs in the presence of IL-3, IL-6, GM-CSF, and SCF without stromal cell support may result in impairment of engraftment capacity, which may be overcome by coculture with PMVECs.

Animals↗