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L Corash

Publications and source records attributed to L Corash.

At least 37 records · Page 2Linked to original sources
PubMed1998

Duck hepatitis B virus inactivation and 8-methoxypsoralen photoadduct formation in human platelet concentrates.

Photochemical inactivation (PCI) of virus and bacteria in platelet concentrates (PC) has been demonstrated using 8-methoxypsoralen (8-MOP) and long-wavelength UV light (UVA). To study inactivation of blood-borne virus, we have employed duck hepatitis B virus (DHBV), a model for human hepatitis B virus. A specific hepatocyte culture infectivity assay, with PCR detection, could measure 5-6 log10 virus kill. The DHBV inactivation in PC was dependent on UVA dose, was enhanced when plasma was reduced from 100% to 20% and was limited by 8-MOP solubility in the reduced-plasma medium. Optimum conditions for PCI were 100 micrograms/mL 8-MOP in 20% plasma and 80% synthetic platelet storage medium. A radiolabeling assay for 8-MOP photoadducts in hepatocytes seeded into PC confirmed that DHBV inactivation reflected DNA modification and indicated that adduct formation was insensitive to minor variations in conditions. Kinetic modeling indicated that optimum adduct formation was a compromise between 8-MOP dark binding and optical transmittance and that plasma proteins competed for 8-MOP binding. The PCI results in various media correlated with corresponding DNA modification densities and were compared to statistical models incorporating DHBV characteristics and predictions of 8-MOP crosslink formation between DNA strands. Behavior was consistent with one or a small number of lethal modifications per DNA strand, including monoadducts, but probably not crosslinks alone. A minor subpopulation of DHBV was found to be somewhat more difficult to inactivate, consistent with three-fold lower modification, due possibly to single-stranded DNA character or host repair of photoadducts.

Blood Platelets↗
PubMed1997

Photochemical inactivation of viruses and bacteria in platelet concentrates by use of a novel psoralen and long-wavelength ultraviolet light.

BACKGROUND: A photochemical treatment process has been developed for the inactivation of viruses and bacteria in platelet concentrates. This process is based on the photochemical reaction of a novel psoralen, S-59, with nucleic acids upon illumination with long-wavelength ultraviolet light (UVA, 320-400 nm). STUDY DESIGN AND METHODS: High levels of pathogens were added to single-donor platelet concentrates containing 3 to 5 x 10(11) platelets in 300 mL of 35-percent autologous plasma and 65-percent platelet additive solution. After treatment with S-59 (150 microM) and UVA (0-3 J/cm2), the infectivity of each pathogen was measured with established biologic assays. In vitro platelet function after photochemical treatment was evaluated during 7 days of storage by using a panel of 14 assays. The in vivo recovery and life span of photochemically treated platelets were evaluated after 24 hours of storage in a primate transfusion model. RESULTS: The following levels of pathogen inactivation were achieved: >10(6.7) plaque-forming units (PFU) per mL of cell-free human immunodeficiency virus (HIV), >10(6.6) PFU per mL of cell-associated HIV, >10(6.8) infectious dose (ID50) per mL of duck hepatitis B virus (a model for hepatitis B virus), >10(6.5) PFU per mL of bovine viral diarrhea virus (a model for hepatitis C virus), >10(6.6) colony-forming units of Staphylococcus epidermidis, and >10(5.6) colony-forming units of Klebsiella pneumoniae. Expression of integrated HIV was inhibited by 0.1 microM S-59 and 1 J per cm2 of UVA. In vitro and in vivo platelet function were adequately maintained after antiviral and antibacterial treatment. CONCLUSION: Photochemical treatment of platelet concentrates offers the potential for reducing transfusion-related viral and bacterial diseases.

Animals↗
PubMed1997

Multiple myeloma arising from monoclonal gammopathy of undetermined significance in a patient with Gaucher's disease.

We report the case of a 64-year-old woman who, 12 years after receiving a diagnosis of Gaucher's disease with concurrent monoclonal gammopathy of undetermined significance, developed worsening thrombocytopenia and bone pain. Bone marrow biopsy at this time revealed 50% plasma cells with a serum monoclonal immunoglobulin A-lambda level of 3.2 g/L. Roentgenography revealed a lytic clavicular lesion, and a diagnosis of multiple myeloma was made. To our knowledge, this case is the first to document the evolution of a monoclonal gammopathy of undetermined significance to multiple myeloma in a patient with Gaucher's disease. The importance of investigating cytopenias and increased bone pain in such patients, perhaps by bone marrow biopsy, to rule out potentially malignant plasma cell dyscrasias is stressed.

Bone Marrow↗
PubMed1996

Photochemical inactivation of duck hepatitis B virus in human platelet concentrates: a model of surrogate human hepatitis B virus infectivity.

BACKGROUND: Photochemical decontamination of platelet concentrates (PCs) has been demonstrated by the use of 8-methoxypsoralen and ultraviolet A light. Systems for studying the inactivation of blood-borne viruses facilitate the evaluation of photochemical decontamination protocols. STUDY DESIGN AND METHODS: Duck hepatitis B virus (HBV), a model for human HBV, was adapted for the study of hepadnavirus inactivation. A highly specific in vitro infectivity assay used primary duck hepatocyte cultures and was followed by the detection of replicated duck HBV sequences. RESULTS: Duck HBV-infected primary duck hepatocyte cultures produced authentic infectious virus. High-titer (> 10(9) virus genome equivalents/mL) duck HBV-infected sera were completely inactivated in serum or PCs by the use of 100 micrograms per mL of 8-methoxypsoralen and 70 J per cm2 of ultraviolet A light. Intracellular duck HBV (> 4.2 log10) in PCs was also inactivated. Culture results were confirmed by a sensitive duckling infectivity assay that indicated that 6.3 log10 of infectious duck HBV had been inactivated by photochemical decontamination. CONCLUSION: The sensitivity of the culture assay was comparable to that of the duckling assay using polymerase chain reaction gene amplification to detect duck HBV. Duck HBV inactivation in PCs was dependent on the dose of ultraviolet A light and independent of 8-methoxypsoralen concentrations of 100 to 300 micrograms per mL: 100 micrograms per mL 8-methoxypsoralen inactivated 4 to 5 log10 of virus in conjunction with 20 to 40 J per cm2 of ultraviolet A light. The polymerase chain reaction-enhanced duck HBV culture system has utility in optimizing photochemical decontamination protocols.

Animals↗
PubMed1996

Advances in leukocyte differential and peripheral blood stem cell enumeration.

Automated leukocyte differential counting has resulted in a marked improvement of the precision of leukocyte subclass enumeration. With advancement of this technology, algorithms have been developed to identify samples that require manual microscopic review. Complex flagging algorithms permit acceptable false-positive rates with effective use of microscopic review to identify significant morphologic abnormalities. Current literature indicates that the leukocyte differential is a poor case-finding index in both outpatient and inpatient populations. Development of highly automated technology has led to test over-utilization because of ease of performance despite recognized limitations in identifying clinically significant abnormalities. Enumeration of hematopoietic stem cells in harvested peripheral blood or bone marrow is critical for determining whether transplanted cells will produce adequate engraftment. Hematopoietic precursors express the CD34 antigen, are present as rare events in unmobilized blood, and are found in increased numbers after mobilization with chemotherapy with or without G-CSF. Flow cytometric detection of CD34+ cells is more rapid and precise than cell culture techniques and results are available in time to determine if further cell harvesting procedures will be necessary. CD34+ cell concentrations correlate with granulocyte-macrophage colony-forming unit counts as well as with time to engraftment. Although intralaboratory precision in measuring these infrequent events may be good, comparisons between different laboratories using aliquots of the same sample have yielded more variable results. Problems in determining precise and reproducible CD34+ cell concentrations may be due to nonspecific antibody binding, insufficient signal intensity of true positive events, differences in monoclonal antibodies and their fluorochrome conjugates, or failure of the total absolute leukocyte count to accurately reflect the population used for CD34 analysis.

Female↗
PubMed1995

Advances in decontamination of blood components.

Despite improved pretransfusion donor evaluation and testing, there is still residual risk of transfusion-associated viral infectious disease. Moreover, other important infectious pathogens, including bacteria, protozoa, and nonenveloped viruses, are not detected in current testing programs. Recent investigations from several laboratories have stimulated interest in decontamination of blood products as an additional means to further enhance the safety of blood transfusion. Furthermore, because testing is a retrospective strategy, a robust decontamination process could provide prospective protection against new pathogens that may enter the blood donor population. Recent advances in decontamination of fresh frozen plasma, plasma derivatives, platelet concentrates, and erythrocytes are reviewed. The introduction of solvent-detergent-treated plasma fractions marks an important advance in transfusion safety. Other technologies for cellular components are emerging to address transfusion-associated infectious disease transmission.

Blood↗
PubMed1995

The pharmacokinetics of 8-methoxypsoralen following i.v. administration in humans.

1. 8-methoxypsoralen (8-MOP) is a naturally occurring photoreactive substance which, in the presence of u.v. light, forms covalent adducts with pyrimidine bases in nucleic acids. For many years, 8-MOP has been used in PUVA therapy for treatment of psoriasis. Recently, the drug has been found to inactivate effectively bacteria spiked into platelet concentrates. The purpose of this study was to determine the pharmacokinetics and safety of 8-MOP administered intravenously in the bactericidal dosage range. 2. Eighteen volunteers were divided into three treatment groups to receive, respectively, 5, 10, and 15 mg 8-MOP infused over 60 min. Frequent arterial samples were gathered, and the blood and plasma were assayed for 8-MOP concentration. The pharmacokinetic parameters were determined by moment and compartmental population analysis, the latter performed with the program NONMEM. Haemodynamics, ventilatory pattern, and subjective effects were recorded throughout the study. 3. The intravenously administered 8-MOP was well tolerated in all individuals, and no acute toxicity was observed. 4. The pharmacokinetics of 8-MOP were best described by a three-compartment mammillary model in which the volumes and clearances were proportional to weight. The mean pharmacokinetic parameters for the plasma concentrations were: V1 = 0.045 1 kg-1, V2 = 0.57 1 kg-1, V3 = 0.15 1 kg-1, CL1 (systemic) = 0.010 1 kg-1 min-1, CL2 = 0.0067 1 kg-1 min-1, CL3 = 0.012 1 kg-1 min-1. The mean pharmacokinetic parameters for the blood concentrations were: V1 = 0.061 1 kg-1, V2 = 1.15 1 kg-1, V3 = 0.21 1 kg-1, CL1 (systemic) = 0.015 1 kg-1 min-1, CL2 = 0.011 1 kg-1 min-1 and CL3 = 0.015 1 kg-1 min-1. 5. The plasma pharmacokinetic model described the observations with a median absolute error of 17%, and the blood pharmacokinetic model described the observations with a median absolute error of 18%. Analysis of the relative concentration of 8-MOP between plasma and red blood cells suggested concentration-dependent partitioning. 6. The addition of 7.5 mg 8-MOP to 300 ml platelet concentrate would produce bactericidal concentrations of 25 micrograms ml-1. Simulations based upon our data show that intravenous administration of 7.5 mg over 60 min would result in systemic concentrations of 8-MOP similar to those observed with conventional PUVA therapy. We conclude that the extensive safety history established in PUVA therapy will be applicable to this new application of 8-MOP.

Adolescent↗
PubMed1994

Photochemical inactivation of pathogenic bacteria in human platelet concentrates.

Platelet concentrates (PC) may be infrequently contaminated with low levels of bacteria that can cause septicemia and death in patients receiving transfusion therapy. We evaluated the efficacy of a photochemical decontamination (PCD) technique using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA) to inactivate bacteria in standard therapeutic PC. Twelve phylogenetically distinct pathogenic bacteria, 5 gram-positive and 7 gram-negative organisms, were seeded into PC to a final challenge dose ranging from 10(5) to 10(7) colony-forming units (CFU)/mL. Contaminated PC were treated with 8-MOP (5 micrograms/mL) and 5 J/cm2 of UVA, a PCD treatment regimen found to adequately preserve in vitro platelet function. Greater than 10(5) CFU/mL of all 5 gram-positive (Staphylococcus aureus, Streptococcus epidermidis, Streptococcus pyogenes, Listeria monocytogenes, and Corynebacterium minutissimum) and 2 of the gram-negative (Escherichia coli and Yersinia enterocolitica) organisms were inactivated. The remaining 5 gram-negative organisms were more resistant, with less than 10(1) to 10(3.7) CFU/mL inactivated under these conditions. The inactivation efficiency for this resistant group of gram-negative organisms was improved when PC were resuspended in a synthetic storage medium with reduced plasma protein concentration (15%) and an increased 8-MOP concentration (23.4 micrograms/mL). Illumination with 3 J/cm2 of UVA in this system inactivated greater than 10(5) CFU/mL of 4 resistant gram-negative organisms (Salmonella choleraesuis, Enterobacter cloacae, Serratia marcescens, and Klebsiella pneumoniae) and 10(4.1) CFU/mL of the most resistant gram-negative organism (Pseudomonas aeruginosa). This level of PCD treatment did not adversely affect in vitro platelet function. These results demonstrate that PCD using 8-MOP (5 to 23.4 micrograms/mL) effectively inactivated high levels of pathogenic bacteria in PC with adequate preservation of in vitro platelet properties.

Adult↗
PubMed1994

Flow cytometric reticulocyte analysis. Multiinstitutional interlaboratory correlation study.

Reticulocyte analysis by flow cytometry offers precision and sensitivity greater than those of conventional morphologic methods and permits derivation of a reticulocyte maturity index. However, interlaboratory variability has not yet been reported. The authors analyzed 310 samples at eight sites using 11 instruments over a 4-month period to examine intermethod and interlaboratory variabilities. Stains included thiazole orange, ethidium bromide, and auramine O. Instruments included models by Coulter, Becton Dickinson, TOA Medical Electronics, and Ortho Diagnostics. The coefficient of variation (CV) among all sites and methods on these samples varied as a function of the reticulocyte percentage, ranging from a mean CV of 69% for samples with < .5% reticulocytes to 24.1% for those with > 2.5% reticulocytes. The best performance was observed with the TOA R-1000 dedicated reticulocyte analyzers, with a mean CV of 18.4% for samples with < .5% reticulocytes and 4.6% for samples with > 2.5% reticulocytes. The reticulocyte maturity index showed comparable intersite precision, with a mean CV of 16% for samples with > 2.5% reticulocytes with multipurpose flow cytometers and a mean CV of 7.3% with the TOA R-1000 instruments. Interclass correlations among all sites ranged from .79 to .99 for the reticulocyte counts and .41 to .88 for the reticulocyte maturity index. The authors conclude that flow cytometric reticulocyte analysis is more precise than manual reticulocyte analysis. With greater automation of this methodology, further interlaboratory standardization of reticulocyte counts and the reticulocyte maturity index can be achieved.

Adolescent↗
PubMed1993

Photochemical inactivation of cell-associated human immunodeficiency virus in platelet concentrates.

Photochemical decontamination (PCD) of platelet concentrates, with adequate preservation of platelet function, has been shown using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA). To further evaluate this technique, models for the inactivation of pathogenic human cell-associated viruses and integrated proviral sequences are required. We have assessed the ability of the PCD technique to inactivate cell-associated human immunodeficiency virus 1 (HIV-1) in platelet concentrates. We correlated PCD inhibition of HIV-1 infectivity with 8-MOP-DNA adduct formation in contaminating nucleated cells, and measured the inhibition of polymerase chain reaction (PCR)-mediated amplification of cellular DNA sequences as a surrogate for inactivation of integrated proviral nucleic acid sequences. After PCD treatment (8-MOP 300 micrograms/mL, UVA 17 mW/cm2) for 60 minutes, 0.5 x 10(6) plaque-forming units (PFU)/mL of cell-associated HIV-1 were inactivated and no virus was detectable by infectivity assay. After 60 minutes of PCD, 15 8-MOP-DNA adducts per 1,000 bp were formed, while in the absence of UVA, no adducts were formed. PCR-mediated amplification of a 242-bp cellular DNA sequence (HLA-DQ-alpha) was inhibited when greater than eight psoralen-DNA adducts per 1,000 bp were present. These studies indicate that high titers of cell-associated HIV-1 in platelet concentrates were inactivated by PCD, and the numbers of 8-MOP-DNA adducts in nucleated cells were sufficient to inhibit amplification of DNA segments that encode for as few as 80 amino acids. Based on the frequency of 8-MOP-DNA adducts, for the 10-kb HIV-1 genome, the probability of an integrated genome without at least one 8-MOP adduct after 60 minutes of PCD was 10(-33).

Blood Component Transfusion↗
PubMed1993

Failure of the International Normalized Ratio to generate consistent results within a local medical community.

Use of the International Normalized Ratio (INR) has been recommended as a means of standardizing prothrombin time (PT) results for management of oral anticoagulant therapy. During the evaluation of a new lot of thromboplastin reagent, however, INR values were obtained that were inconsistent with results obtained with the prior lot of reagent from the same manufacturer. A local normalized ratio (LNR) was substituted for the INR for the new reagent, based on a calculated local sensitivity index (LSI). Validation of the LSI was performed at the three hospitals in the medical community by testing an identical panel of aliquots from 64 plasmas obtained from patients who were chronically receiving oral anticoagulants. Each test result was classified according to the INR value as low, low therapeutic, high therapeutic, or high. Local normalized ratio values obtained at one hospital in the community were in reasonable agreement with INR determinations in the other two hospital laboratories. Classification mismatches occurred using the INR, however, in 84 of 280 (30%) of the paired samples. Thus, the inability to generate consistent INR values within a local medical community raises serious concern about the reliability of the INR concept in its current form.

Anticoagulants↗
PubMed1992

Use of 8-methoxypsoralen and long wavelength ultraviolet radiation for decontamination of platelet concentrates.

Transmission of viral diseases through blood products remains a problem in transfusion medicine. We have developed a photochemical decontamination system (PCD) for platelet concentrates (PC) utilizing treatment with long wavelength ultraviolet radiation (UVA, 320-400 nm) and 8-methoxypsorlan (8-MOP). This system is capable of inactivating 25-30 logs/hour of bacteria E. coli or S. aureus, 6 logs/hour of bacteriophage fd, 0.9 log/hour of bacteriophage R17, and 1.1 logs/hour of feline leukemia virus (FeLV) in PC. Immediately following 6 hours of PCD treatment, platelet integrity and function of PCD-treated and control PC were equivalent. After overnight storage, PCD-treated and control PC platelet properties were equal, but there was a slight reduction in TXB-2 production of PCD-treated PC compared to controls. Following PCD treatment, PC were stored for 48 to 96 hours. Platelet counts, morphology scores, extracellular LDH levels, aggregation response, dense body (db) content, and alpha granule (alpha g) content of PCD-treated and control PC were comparable. We assessed the ability of the PCD technique to inactivate intracellular and extracellular virus, quantified the degree of DNA adduct formation in contaminating lymphocytes, and measured the inhibition of polymerase chain reaction (PCR) mediated amplification of intracellular DNA. High titers of cell-free murine cytomegalovirus added to human platelet concentrates (final concentration 10(6)) were inactivated by PCD within 30 minutes. Cat renal fibroblasts infected at high levels with feline rhinotracheitis virus (FeRTV) were seeded into PC followed by PCD treatment with inactivation of 4.8 logs of FeRTV within 10 minutes. Purified human lymphocytes were seeded into PC and treated with PCD in the presence of 3H 8-MOP. Six hours of PCD treatment resulted in the formation of 9.3 to 12.8 8-MOP adducts per 1000 base pairs (bp) of DNA. PCR amplification of a 242 bp segment at the HLA-DQ alpha locus was examined. Inhibition of PCR DNA amplification was dependent on the numbers of 8-MOP adducts formed, and no amplification was present when greater than 12 adducts per 1000 bp were formed. These studies indicate that PCD can effectively inactivate high titers of cell-associated and cell-free virus seeded into standard human PC. The efficiency of DNA adduct formation can be quantitated, and the level of 8-MOP adduct formation in lymphocytes contaminating PC is comparable to the level of adduct formation in cellular DNA reported in the absence of platelets.

Blood Component Transfusion↗
PubMed1992

Histologic studies of splenic megakaryocytes after bone marrow ablation with strontium 90.

We previously showed that purified strontium 90 produced sustained bone marrow ablation in mice, lowering platelet levels to less than 10% of normal 11 days after administration. Platelet levels later rose exclusively from splenic production and were maintained at a stable level (58% of normal) from 20 to 115 days after injection. However, there was no change in the total number or ploidy distribution of splenic megakaryocytes, as immunologically detected by flow cytometry. To further study the characteristics of splenic thrombopoiesis after bone marrow ablation by 90Sr, we measured the frequency, cross-sectional area, and endomitotic figures of histologically recognizable megakaryocytes (as well as bare megakaryocyte nuclei) in mouse spleen sections. During the hematopoietic nadir 9 days after injection of yttrium 90-free 90Sr, the size (area) of megakaryocyte cross-sections (mean +/- SD, 1079.3 +/- 661.6 microns 2; normal, 398.7 +/- 192.8 microns 2) was greater than for any other time studied, but megakaryocyte frequency (corrected for size) did not increase until day 16. Overall, splenic megakaryocytes in marrow-ablated mice 16 or more days after 90Sr injection showed substantial increases (p = 0.001 for both comparisons) in mean area (707.5 +/- 386.2 microns 2) and sectional frequency (mean +/- SEM, 4.52 +/- 0.20 per 1.83 mm2; normal, 0.78 +/- 0.06 per 1.83 mm2). Megakaryocyte bare nuclei and endomitotic figures were also more numerous after 90Sr, injection, suggesting acceleration of megakaryocyte maturation and platelet production. The induction of splenic platelet production after bone marrow ablation is associated with increased size of recognizable megakaryocytes, despite lack of change in overall splenic megakaryocyte ploidy.

Animals↗
PubMed1992

Photochemical inactivation of viruses and bacteriophage in plasma and plasma fractions.

Transfusion-associated transmission of viral diseases remains a problem. A number of methods have been developed to inactivate viral pathogens in plasma and plasma fractions, including: dry heating, wet heating, solvent-detergent treatment, and immunoaffinity purification. While some of these methods successfully inactivate pathogenic viruses, inactivation may be incomplete or result in damage to labile plasma proteins. We have developed a method of photochemical decontamination (PCD) using psoralens and long wavelength ultraviolet light to inactivate pathogenic viruses. In the present study, a spectrum of model viruses have been added to plasma and plasma fractions to examine the efficiency of photochemical decontamination and the effects on labile plasma coagulation factors. Both RNA and DNA viruses have been inactivated under conditions which permit preservation of coagulation protein function. PCD technology appears to offer a promising solution to decontamination of blood products.

Bacteriophages↗