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Biomedical subjects

J Burkhart

Publications and source records attributed to J Burkhart.

17 recordsLinked to original sources
PubMed2007

Comparison of three bacterial detection methods under routine conditions.

BACKGROUND AND OBJECTIVES: Since 2004, bacterial screening of platelets has been required in the USA and is also done on a voluntary basis in many European countries. The German Red Cross blood donor services conducted a prospective multicentre study in order to investigate the prevalence of bacterially contaminated pool platelet concentrates and apheresis platelet concentrates. This substudy compares three different bacterial detection systems. STUDY DESIGN AND METHODS: Platelet concentrates were tested in parallel with BacT/ALERT, Scansystem and Pall eBDS (n = 6307) in pool platelets. Apheresis platelets were tested in parallel with BacT/ALERT and Pall eBDS (n = 4730). All initially positive results were evaluated by a standardized procedure including evaluation by a microbiology reference laboratory. RESULTS: One in 6307 pool platelets were confirmed positive by BacT/ALERT, whereas Pall eBDS and Scansystem failed to detect these samples. Only three samples were initially reactive with Pall eBDS without proof of any bacteria strains. The rate of false-positive results was substantially higher for BacT/ALERT (0.25%, 28 in 11,037 tested samples) than for eBDS (0.03%, 3 in 11 037 tested samples) or Scansystem (0.0%, 0 in 6307 tested samples). Three of 4730 apheresis platelets were confirmed positive by BacT/ALERT. These were negative with Pall eBDS. CONCLUSION: Sensitivity was best for BacT/ALERT, whereas specificity was enhanced for Pall eBDS and Scansystem. Scansystem required specially trained staff, whereas BacT/ALERT and Pall eBDS were easy, quick, user-friendly and objective methods.

Bacteria↗
PubMed2006

Analysis and cryopreservation of hematopoietic stem and progenitor cells from umbilical cord blood.

BACKGROUND: Umbilical cord blood (UCB) is an important source of hematopoietic stem and progenitor cells (HSC/HPC) for the reconstitution of the hematopoietic system after clinical transplantation. Cryopreservation of these cells is critical for UCB banking and transplantation as well as for research applications by providing readily available specimens. The objective of this study was to optimize cryopreservation conditions for CD34+ HSC/HPC from UCB. METHODS: Cryopreservation of CD34+ HSC/HPC from UCB after mononuclear cell (MNC) preparation was tested in a research-scale setup. Experimental variations were concentration of the cryoprotectant, the protein additive and cell concentration. In addition, protocols involving slow, serial addition and removal of DMSO were compared with standard protocols (fast addition and removal of DMSO) in order to avoid osmotic stress for the cryopreserved cells. Viability and recoveries of MNC, CD34+ cells and total colony-forming units (CFU) were calculated as read-outs. In addition, sterility testing of the collected UCB units before further processing was performed. RESULTS: The optimal conditions for cryopreservation of CD34+ HPC in MNC preparations were 10% DMSO and 2% human albumin at high cell concentrations (5 x 10(7) MNC/mL) with fast addition and removal of DMSO. After cryopreservation using a computer-controlled freezer, high viabilities (89%) and recoveries for CD34+ cells (89%) as well as for CFU (88%) were observed. Microbial contamination of the collected UCB samples was reduced to a rate of 6.4%. DISCUSSION: Optimized cryopreservation conditions were developed for UCB MNC in respect of the composition of the cryosolution. In addition, our results showed that fast addition of DMSO is essential for improved cryopreservation and post-thaw quality assessment results, whereas the speed of DMSO removal after thawing has little influence on the recoveries of CD34+ cells and CFU.

Antigens, CD34↗
PubMed2005

Filter Buffy Coats (FBC): a source of peripheral blood leukocytes recovered from leukocyte depletion filters.

In compliance with federal regulations, blood banks routinely use leukocyte depletion filters to eliminate contaminating leukocytes from blood products such as red blood cell and platelet concentrates. We developed and optimized conditions to elute leukocytes adsorbed to these filters; resulting in leukocyte suspensions which we termed Filter Buffy Coats (FBCs). These Filter Buffy Coats can replace standard buffy coats for various research applications. After optimizing both the filter elution medium as well as elution protocols, we compared commonly used leukocyte depletion filters from four different manufacturers. Relative fractions as well as total recoveries of leukocyte subsets, such as lymphocytes, monocytes and granulocytes, found in Filter Buffy Coats were identified and compared among the filters as well as to standard buffy coats and whole blood. Flow cytometric analysis of Filter Buffy Coats confirmed the presence of T- and B-lymphocytes, NK cells and monocytes. Furthermore, a significant quantity of CD34(+) hematopoietic stem or progenitor cells (HSC/HPC) was detected in Filter Buffy Coats prepared from different filters, thus making FBCs a valuable source for research on HSC/HPC. Colony assays revealed that most of these CD34(+) cells are functional. Using immunomagnetic cell sorting (MACS), we isolated a variety of leukocyte populations from FBC mononuclear cells (Filter-PBMCs) including T lymphocytes (CD4(+), CD8(+), CD3(+)), B lymphocytes (CD19(+)), NK cells (CD56(+)), HSC/HPC (CD34(+), CD133(+)) or dendritic cells (BDCA-4(+)). Functional properties of Filter-PBMCs, as well as of some of these isolated leukocyte populations, were confirmed using standard assays. In summary, Filter Buffy Coats are a valuable and convenient source of different peripheral leukocyte populations and can replace standard buffy coat preparations for research applications.

Antigens, CD↗
PubMed2005

[The STEMMAT-project as part of health initiative BayernAktiv: adult stem cells from umbilical cord and cord blood as alternative to embryonic stem cell research].

Adult stem cells from umbilical cord and cord blood are an interesting alternative to embryonic stem cells because such research is commonly recognized as ethical undisputed and many aspects are still insufficiently investigated. In the context of the STEMMAT research project (STEM = Stem Cell and MAT = Material) different aspects of stem cells from umbilical cord and cord blood are investigated, to improve basic science understanding and potentially leading someday to a clinical application.

Cord Blood Stem Cell Transplantation↗
PubMed2000

The hospital oxygen supply: an "O2K" problem.

BACKGROUND: As an essential hospital facility, the central oxygen supply system should be designed with features allowing backup and/or redundancy in the event of system failure. As part of an organized institutional review of The Cleveland Clinic Foundation hospital inpatient central oxygen supply system, we undertook a survey of all hospitals in two Ohio cities to determine the characteristics of hospital central supply systems. METHODS: The questionnaire was developed and completed by structured telephone interview during calls placed to managers of facilities engineering departments in 35 hospitals in the greater Cleveland and Columbus, Ohio, metropolitan areas. To encourage candid responses to the telephone interview, respondents were assured that institutional names would not be presented in published reports. The questionnaire addressed the type of primary and reserve oxygen sources in the hospital, whether a backup system exists, and if so, in what configuration. The questionnaire also addressed whether any unplanned interruption or other problem (such as contamination of the piped-in oxygen supply) had ever occurred in the facility. RESULTS: Of the 35 eligible hospitals, responses were available from 32 (91.4%). The mean number of beds in the hospitals responding was 397 +/- 251 (standard deviation), and the original construction dates of the responding hospitals ranged from 1887 to 1982. All 32 responding institutions reported a reserve system, described as a liquid reservoir in 72% (23/32), manifolded cylinders in 16% (5/32), and both in 13% (4/32). Twenty-six (81%) of those responding reported having the reserve supply liquid or manifolded gas cylinders at the same location as the primary liquid vessel. The supply lines of these contiguous primary and reserve containers were reported to join proximal to entering the hospital structure, so at each of these 26 hospitals the primary and reserve systems depend on a single length of pipe. Only 4 (13%) of the hospitals have manifolded cylinders in addition to the primary and reserve liquid supplies. These manifolds are in different locations from the primary and reserve, have physically separate feed lines, and represent the only true examples of redundant piped-in oxygen supplies recorded during the survey. Of the 32 hospitals surveyed, 5 (16%) reported having experienced mishaps with the bulk liquid supply. CONCLUSIONS: (1) Not surprisingly, most of the hospitals in these two urban areas use bulk liquid oxygen systems (with primary and reserve liquid reservoirs) as the main central supply source, with some providing manifolded cylinders as backup. (2) Mishaps regarding the main supply line from the bulk oxygen reservoir were reported by 16% (5/32) of responding institutions. (3) In this context, the fact that most main and reserve tanks were contiguous and fed through a single line to the hospital facility suggests ongoing risk for interruption of an oxygen supply by line mishaps (e.g., street repair). (4) Contingency planning to lessen the risk of an interrupted supply should involve back-up systems with physically separated feed lines, as well as tanks of manifolded cylinders along the course of the main hospital oxygen circuit line.

Disaster Planning↗
PubMed1999

Environmental study of nylon flocking process.

Environmental measurements for a variety of gas, particulate, and microbiological agents have been made in order to characterize exposures associated with the nylon flocking process. Of all agents measured, particulate is the predominant exposure. Levels of total particulate ranged from O.1 to 240 mg/m3 (x = 11.4 mg/m3). Average respirable particulate was 2.2 mg/m3, ranging from 0.5 to 39.9 mg/m3. Highest levels of particulates were found in the flocking room, and direct reading dust measurements indicate that the highest peak exposures are associated with "blowdown" (a cleaning procedure used between flocking runs). The nature of the airborne particles was investigated using polarized light and scanning electron microscopy. Air samples were found to contain flock particles (fibers nominally 10-15 microm in diameter by about 1000 microm in length) and a variety of respirable particles types, several of which were linked directly to the process. Of special interest were elongated respirable particles, which by microscopic analysis, complemented with melting-point determination, were found to be shreds of nylon.

Air Pollutants, Occupational↗
PubMed1999

Acute inflammatory reaction in rats after intratracheal instillation of material collected from a nylon flocking plant.

Several cases of interstitial lung disease have been diagnosed among workers at a nylon flock plant, but the etiologic agent for the disease outbreak was unknown. The results of a medical survey and industrial hygiene study indicated that the dust present in the plant may be responsible. Thus, airborne dust collected at the plant was examined for its inflammatory potential in rat lungs. The endpoints measured were: (1) breathing rates, (2) differential cell counts of bronchoalveolar lavage cells, (3) alveolar macrophage (AM) chemiluminescence, (4) albumin concentration and matrix metalloprotease activities in the acellular fluid from the initial bronchoalveolar lavage, and (5) pulmonary histopathology. In the first study, rats received a single dose of the airborne dust sample (10 mg/kg body weight) by intratracheal (IT) instillation. At 1 d post-IT, all inflammatory endpoints were significantly increased versus controls, but by 29 d post-IT they did not differ significantly from controls. Histopathology demonstrated mild to moderate, multifocal, suppurative pneumonia, usually centered around bronchioles, at 1 d post-IT. At 29 d post-IT, pulmonary inflammation was minimal to mild and characterized by alveolar histocytosis usually restricted to the immediate area of retained bire-fringent fibers. In subsequent experiments, airborne dust was extracted with water and the dust (washed airborne dust) and water extract (soluble fraction) were separated by centrifugation for further study. Nylon tow dust was prepared in the laboratory by milling uncut nylon strands (called tow) that had not been treated with the finish or dyes that are commonly used in the flock plants. Rats were administered a single dose of a dust sample (10 mg/kg body weight) or the soluble fraction (1.3 ml/kg body weight) by IT administration and the same endpoints were measured at 1 d post-IT. The dust samples caused significant increases in all of the inflammatory endpoints; however, the soluble fraction was much less active. Histological analysis of the lungs 1 d post-IT confirmed lung inflammation was occurring and tended to center around bronchioles. The results suggest that: (1) nylon flocking generates particles of respirable size that can interact with AM in the lung and can be detected in the lung 29 d after exposure, (2) the dust samples examined cause an inflammatory response, (3) water-extractable agent(s) from airborne dust contribute only minimally to the inflammatory response, and (4) the acute inflammatory response to these dusts is substantial when compared to other pathologic occupational dusts previously examined in our laboratory.

Acute Disease↗
PubMed1995

International Commission for Protection Against Environmental Mutagens and Carcinogens. Genetic risk extrapolation from animal data to human disease. A Taskgroup Report. No. 00105.

This report describes a model for producing quantitative genetic risk assessments for human populations. The model is patterned after current methods used in cancer risk analysis. The risk to humans is expressed as the number of additional dominant genetic diseases added to the existing genetic burden, in the offspring of the exposed individuals.

Animals↗
PubMed1993

Physician-ordered respiratory care vs physician-ordered use of a respiratory therapy consult service: early experience at The Cleveland Clinic Foundation.

BACKGROUND: Accumulative evidence suggests that respiratory care is frequently misallocated. We report the results of a pilot study of a delivery system aimed at correcting such misallocation. METHODS: The delivery system (Respiratory Therapy Consult Service, or RTCS) allows respiratory therapists (when requested by the case-managing physician) to determine respiratory care, with decisions guided by algorithm (ie, Consult patients). In the pilot study, Therapist Evaluators responded to requests for Consults on two study wards. All staff therapists participated in implementing Evaluator-determined treatment. STUDY DESIGN: We evaluated 38 patients (20 of whom were Consult patients) randomly selected from a total of 82 patients undergoing abdominal surgery during the study period. RESULTS: Consult patients were significantly older than non-Consult patients, more likely to be heavy smokers (67 vs 43%), and sicker as suggested by a higher Triage Score. Consult patients received more types and more total respiratory care services, demonstrated a trend toward longer stay, and had significantly higher respiratory therapy charges. CONCLUSION: Our experience shows that a consult program can be successfully implemented in a large, tertiary care institution with widespread physician and nursing support. Whether the RTCS fulfills its goal of ameliorating misallocation of respiratory care has yet to be proven and awaits the completion of other studies currently under way.

Abdomen↗
PubMed1991

Environmental study of firefighters.

A study of firefighter exposures was undertaken at the request of the U.S. Fire Administration. This work was part of a larger study which included field evaluation of the performance of the self-contained breathing apparatus (SCBA) worn by firefighters during structural firefighting. Measurements were made for a variety of contaminants including CO, CO2, benzene, HCN, HCl, H2SO4, HF, acrolein, CH4, formaldehyde and PNAs. Many of the analyses were performed by collection of bag samples followed by Fourier transform infrared spectroscopy using a field mobile spectrometer. Measurements were also made using solid sorbent tubes and direct-reading meters. Sampling was done both during the knockdown and during overhaul phases of structural firefighting. Also, in order to estimate exposures including those when the SCBAs were worn, measurements were made both inside and outside the SCBA facepiece. Carbon monoxide was the most common contaminant found during knockdown, and about 10% of the samples were greater than 1500 ppm. Formaldehyde, acrolein, hydrogen chloride, hydrogen cyanide, sulphuric acid and hydrogen fluoride all exceeded their respective short-term exposure limits (STEL) on some occasions. Approximately 50% of the knockdown samples for acrolein exceeded the STEL. During overhaul, when masks were usually not worn, many of the contaminants found during knockdown were detected, but typically at much lower concentrations. Inside-mask sampling data suggest that exposure to low concentrations of a variety of compounds is occurring but this is believed to be principally the result of early mask removal or of non-use during knockdown rather than of leakage. The three basic sampling approaches (bag sampling, sorbent tubes and direct-reading meters) proved in this study to be complementary and served to maximize our ability to detect and quantify a wide range of combustion products.

Air Pollutants, Occupational↗
PubMed1976

Transfer of alcohols and ureas across the oral mucosa measured using streaming potentials and radioisotopes.

The permeability of the oral mucosa to an alcohol and a urea series was studied using radioisotope transfer and the measurement of streaming potentials. Both methods yielded similar quantitative estimates of permeability. The rate of transfer of the smallest member of both series (methanol and urea) was greater than the second member (ethanol and methylurea). In the alcohol series, permeability increased as the chain length increased from ethanol to butanol. In contrast, the permeability of the oral mucosa to ethylurea and propylurea was less than to methylurea. However, butylurea had a greater rate of transfer than either propylurea or ethylurea.

Alcohols↗