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At least 127 records · Page 7Linked to original sources
PubMed2003

Rapid routine structure determination of macromolecular assemblies using electron microscopy: current progress and further challenges.

Although the methodology of molecular microscopy has enormous potential, it is time consuming and labor intensive. The techniques required to produce a three-dimensional (3D) electron density map of a macromolecular structure normally require manual operation of an electron microscope by a skilled operator and manual supervision of the sometimes complex software needed for analysis and calculation of 3D maps. Systems to automate the process of data acquisition from an electron microscope are being developing and these systems are being integrated with specimen handling operations and post acquisition data processing. Here, the current performance of our existing systems and the future challenges involved in substantially improving both the sustained throughput and the yield of automated data collection and analysis are reported.

Algorithms↗
PubMed1997

Evaluation of a new, rapid and automated immunochemiluminometric assay for the measurement of serum intact parathyroid hormone.

The Immulite parathyroid hormone (PTH) immunochemiluminometric assay (ICMA) was evaluated by measuring serum PTH concentrations in 134 volunteers and 25 patients with various diseases affecting bone and mineral metabolism and comparing with those measured by the Nichols Allegro immunoradiometric (IRMA) assay. Although the assays were highly correlated (r = 0.99. P < 0.0001), there were discrepancies at lower PTH concentrations which may be explained by the lower limit of detection of the ICMA assay. The anti-coagulants EDTA and heparin appeared to have significant effects on PTH measurement particularly at lower concentrations. Sera assayed by ICMA diluted out more uniformly than in the IRMA and there was no cross reactivity with parathyroid hormone-related peptide in either the IRMA or ICMA. Delays of up to 8 h in specimen handling did not appear to affect PTH measurements. The enhanced sensitivity of the Immulite ICMA intact PTH assay confers an advantage in the diagnosis of both hyper- and hypocalcaemia, while the shorter incubation times, automation and lack of radioactivity are important practical advantages.

Adolescent↗
PubMed2006

Assessment of analytical reproducibility of 1H NMR spectroscopy based metabonomics for large-scale epidemiological research: the INTERMAP Study.

Large-scale population phenotyping for molecular epidemiological studies is subject to all the usual criteria of analytical chemistry. As part of a major phenotyping investigation we have used high-resolution 1H NMR spectroscopy to characterize 24-h urine specimens obtained from population samples in Aito Town, Japan (n = 259), Chicago, IL (n = 315), and Guangxi, China (n = 278). We have investigated analytical reproducibility, urine specimen storage procedures, interinstrument variability, and split specimen detection. Our data show that the multivariate analytical reproducibility of the NMR screening platform was >98% and that most classification errors were due to urine specimen handling inhomogeneity. Differences in metabolite profiles were then assessed for Aito Town, Chicago, and Guangxi population samples; novel combinations of biomarkers were detected that separated the population samples. These cross-population differences in urinary metabolites could be related to genetic, dietary, and gut microbial factors.

Biomarkers↗
PubMedDate not supplied

Use of the activated partial thromboplastin time for the diagnosis of congenital coagulation disorders: problems and possible solutions.

The activated partial thromboplastin time (APTT) is a commonly performed laboratory procedure which is used for multiple purposes including monitoring of heparin therapy, detection of coagulation factor deficiency, and detection of lupus anticoagulants. Among the hereditary coagulation deficiencies, factor VIII and factor IX are the most common. APTT reagents differ widely in both their sensitivity to factor VIII and factor IX deficiencies as well as their responsiveness. Sensitivity may be defined as the ability to identify a deficiency state while responsiveness is indicated by the degree of prolongation of the APTT result as compared to the upper limit of normal. Reagents may be both sensitive and responsive or alternatively sensitive and relatively nonresponsive. Consequently, it is extremely important for each laboratory to carefully identify the upper limit of the normal range. A variety of preanalytical variables will also effect the sensitivity of the APTT to factor deficiency states. These variables include specimen handling and the preparation of platelet poor plasma. The instrument effect is also of importance. Selection of the reagent tends to have the most impact on sensitivity and responsiveness while instrumentation affects the precision of a given APTT. The composition and concentration of phospholipid in APTT reagents does have an effect on reagent responsiveness and sensitivity. Sensitivity to factor deficiencies does not necessarily parallel sensitivity to lupus anticoagulants.

Blood Coagulation Disorders↗
PubMed2003

Combined laparoscopic-assisted right hemicolectomy and low anterior resection for synchronous colorectal carcinomas.

BACKGROUND: Two cases of combined laparoscopic- assisted right hemicolectomy and low anterior resection for malignancy are presented to illustrate the technical aspects of performing two concurrent laparoscopic-assisted bowel resections with sequential anastomosis. Although there are similarities with laparoscopic-assisted total proctocolectomy, the need for complete mesenteric dissection in two areas, removal of two separate specimens containing malignancy, and the need for two anastomoses raise unique technical considerations which include port placement, sequence of dissection, choice of specimen extraction sites, specimen handling, and sites for extracorporeal anastomosis. METHODS: Operative notes, operative videotapes, and hospital inpatient and outpatient records were reviewed for both patients. RESULTS: Laparoscopic-assisted combined resection was completed in both patients. In both cases, laparoscopic total mesorectal excision was performed. Maximum incision length was 6 cm. Both patients were ready for discharge on postoperative day 3. CONCLUSION: Combined laparoscopic assisted right colectomy and low anterior resection can be performed for synchronous colorectal malignancies with curative intent.

Aged↗
PubMed2002

[A new technique for foetal brain fixation and extraction].

We performed a new technique for foetal brain fixation and extraction that offers a remarkable reduction in sampling time facilitates specimen handling while conserving high quality. With the new fixation method, it is possible to obtain samples adequate for macroscopic and microscopic observations and immunohistochemical analysis. The technique involves the creation of an ex vacuo phenomenon in the subarachnoideal space prior to injecting the fixative solution. In this manner, the solution is homogenously distributed. Ease, reproducibility and the possibility of standardizing the procedure are the principal advantages. Low costs, reduced wording time and less need for human resources are other advantages. Histologically, we obtained, quickly, high quality slides with routine and immunohistochemical stains. Disadvantages of the technique derive from the use of formaldehyde and glacial acetic acid, rather than water to wash the samples; thus one must work in a well ventilated area, with gloves, protective glasses and an adequate lab coat to avoid skin and respiratory tract damage.

Brain↗
PubMed1996

Toward optimal laboratory use. Problems in laboratory testing in primary care.

OBJECTIVE: To examine the frequency and characteristics of problems in laboratory testing in primary care physicians's offices and their impact on health care. DESIGN: Prospective descriptive study in which participating office-based primary care clinicians reported each occurrence of any laboratory incident during a 6-month study. Each identified problem was reported on a structured data collection instrument with an open-ended description of the problem. SETTING: Primary care physicians' offices in North America. PARTICIPANTS: One hundred twenty-four primary care clinicians in 49 practices of the Ambulatory Sentinel Practice Network (ASPN). MAIN RESULTS: A total of 180 problems were reported, yielding a crude rate of 1.1 problems per 1000 patient visits. Problems involving test ordering and specimen handling were the most common (56%), while those attributable to the test analysis itself accounted for 13% of the total. In the judgment of the practice staff, 27% of the reported problems had an impact on patient care. Of the 24 cases for which the specific impact was known and reported, half of the impacts were minor and about half were significant, as judged by whether or not the diagnosis and/or treatment of the patient was measurably affected. CONCLUSIONS: Clinically apparent problems with laboratory testing in primary care were found at a rate of 1.1 problems per 1000 patient visits. Of the laboratory problems that occurred in this study, 27% were judged by the physician to have an effect on patient care.

Clinical Laboratory Techniques↗
PubMed1976

Measurement of carbon dioxide in blood.

The remarkable combination of physical and chemical properties displayed by carbon dioxide has enabled the development of a very wide variety of analytical methods for its measurement in blood or blood plasma. Both for historical and technical reasons, the gasometric method of Van Slyke and Neill is preeminent, but great skill is needed to realize its full precision and accuracy. The microgasometer of Natelson, however, has served the clinical laboratory well as a practicable manual means of microanalysis for total carbon dioxide. So far as automated analysis is concerned, it is highly significant that one of the first applications of Skegg's continuous flow principle was to the titrimetric determination of total carbon dioxide in serum; the AutoAnalyzer technique remains the most widely used of its kind, in spite of inherent difficulties in specimen handling, instrumental standardization, and quality control. At the same time, it has been pointed out that the routine determination of total carbon dioxide in serum does not offer a useful screening procedure for identifying or characterizing patients with acid-base disorders; full assessment of acid-base status, including pCO2 in selected patients is much more rewarding. The credit for bringing pCO2 measurements within the scope of the clinical laboratory, by means of the interpolation technique, is largely due to Astrup and his colleagues. Nevertheless, continual improvements have been made in the design and performance of the Severinghaus type of pCO2 electrode, so that reliable instruments offering direct readout of blood pCO2 are available from several manufacturers. The more elaborate versions of these instruments are rugged and work-simplified, and they offer automated self-calibration and end-point detection for pH and pO2, as well as pCO2. It will be surprising if such instruments do not come into widespread use.

Animals↗
PubMed1981

Application of scanning electron microscopy to x-ray analysis of frozen-hydrated sections. II. Analysis of standard solutions and artificial electrolyte gradients.

New specimen handling and analytic techniques for the application of x-ray microanalysis to studies of cell and organ biology have been recently described (Saubermann et al., 1981, J. Cell Biol. 88:257-267). Based on these techniques, absolute quantitative standardization has been established through x-ray analysis of frozen-hydrated and then dried sections of independently measured standard solutions of elements. These experiments demonstrate that the specific techniques employed have a probable error of less than 10%. Artificial electrolyte gradients established in gelatin were subjected to analysis to determine whether there was elemental displacement under non-membrane-limited conditions at the temperatures employed for sectioning (-30 degrees to -40 degrees C). No significant difference was observed between such gradients in serial sections cut at -30 degrees and -80 degrees C. Similarly, no additional ice-crystal-damage artifact was found in sections cut at -30 degrees C when compared with sections cut at -80 degrees C. Thus, in terms of ice-crystal size, gradient maintenance, and compartmental differentiation, cryosectioning at -30 degrees to -40 degrees C was not associated with redistribution incompatible with 1- to 2-micrometers spatial resolution, and absolute measurements of elemental concentration were practical within regions of this size.

Chlorides↗
PubMed2003

Performance characteristics of the TRUGENE HIV-1 Genotyping Kit and the Opengene DNA Sequencing System.

The TRUGENE HIV-1 Genotyping Kit and OpenGene DNA Sequencing System are designed to sequence the protease (PR)- and reverse transcriptase (RT)-coding regions of human immunodeficiency virus type 1 (HIV-1) pol. Studies were undertaken to determine the accuracy of this assay system in detecting resistance-associated mutations and to determine the effects of RNA extraction methods, anticoagulants, specimen handling, and potentially interfering substances. Samples were plasma obtained from HIV-infected subjects or seronegative plasma to which viruses derived from wild-type and mutant infectious molecular clones (IMC) of HIV-1 were added. Extraction methods tested included standard and UltraSensitive AMPLICOR HIV-1 MONITOR, QIAGEN viral RNA extraction mini kit, and QIAGEN Ultra HIV extraction kit, and NASBA manual HIV-1 quantitative NucliSens. Sequence data from test sites were compared to a "gold standard" reference sequence to determine the percent agreement. Comparisons between test and reference sequences at the nucleotide level showed 97.5 to 100% agreement. Similar results were obtained regardless of extraction method, regardless of use of EDTA or acid citrate dextrose as anticoagulant, and despite the presence of triglycerides, bilirubin, hemoglobin, antiretroviral drugs, HIV-2, hepatitis C virus (HCV), HBV, cytomegalovirus, human T-cell leukemia virus type 1 (HTLV-1), or HTLV-2. Samples with HIV-1 RNA titers of >or=1,000 copies/ml gave consistent results. The TRUGENE HIV-1 Genotyping Kit and OpenGene DNA Sequencing System consistently generate highly accurate sequence data when tested with IMC-derived HIV and patient samples.

Anticoagulants↗
PubMed1996

In vitro stability of free prostate-specific antigen (PSA) and prostate-specific antigen (PSA) complexed to alpha 1-antichymotrypsin in blood samples.

OBJECTIVES: To study the in vitro stability of free and complexed forms of prostate specific antigen (PSA) in blood samples in order to establish guidelines for specimen handling, in particular for the clinical utility of the analysis of percentage free PSA. METHODS: Blood samples were collected and processed to generate serum, heparin plasma, and EDTA plasma. Three different two-site immunoassays were used to measure the concentrations of total PSA (PSA-T), free form of PSA (PSA-F), and PSA-alpha 1-antichymotrypsin complex (PSA-ACT) in order to determine the effect of repeated freezing and thawing, delayed separation of serum from blood cells, and stability during storage at 4 degrees C and 30 degrees C. RESULTS: Five cycles of freezing and thawing introduced no statistically significant changes in the measured concentrations of PSA-T, PSA-F, or PSA-ACT. The effect of storing blood samples at room temperature for 1-6 h before separation of serum revealed a statistically significant decrease only for PSA-F after 5.5 h of storage (mean decrease 3.5%). PSA-T and PSA-ACT showed good stability in both serum and plasma samples, whereas PSA-F, after 1 week of storage at 4 degrees C, decreased on average by 28.8%, 7.8%, and 5.6%, respectively, in serum, heparin plasma, and EDTA plasma. The decreases of PSA-F at 4 degrees C were statistically significant (P < 0.05) relative to the controls (samples stored at -20 degrees C) after storage for 23 h in serum, 86 h in heparin plasma, and 71 h in EDTA plasma. When the same samples were stored at 30 degrees C for 24 h, only the mean decrease of PSA-F (4.8%) in serum was statistically significant. CONCLUSIONS: PSA-F in blood samples is less stable than PSA-ACT. It is not advisable to store samples on the clot, especially if time and temperature cannot be controlled. Serum samples should be stored frozen if not analyzed during the same day. After thawing, samples can be stored up to 23 h at 4 degrees C prior to analysis. The use of plasma samples improves the stability of free PSA.

Edetic Acid↗
PubMed1978

Cochlear nerve in neurilemomas. Audiology and histopathology.

Correlative data between the histopathologic changes in the cochlear nerve and audiologic findings are reported in 16 cases of neurilemomas. Poor speech discrimination, positive or absent recruitment, excessive adaptation, or separation of forward vs reverse continuous tone Bekesy tracings did not correlate with the number of preserved nerve fibers. There were several cases with profound hearing loss in which the nerve fiber population approached normal. Histologically, pathologic changes included dilated fibers and increased interfibrillary collagen. In many specimens the fibers were further apart than normally, especially in the immediate vicinity of the tumor, and many lay between tumor cells. The tumor-nerve interface was usually gradual and no abrupt change appeared at the transition from the nerve to the tumor, the Schwann cells appearing to continue as tumor cells. Nonspecific changes apparently due to specimen handling were seen in some areas of most specimens.

Adult↗
PubMed2001

Physician satisfaction and emergency department laboratory test turnaround time.

OBJECTIVES: To determine the length of time for the components of the emergency department (ED) turnaround time (TAT) study in 1998 and to ascertain physician satisfaction concerning laboratory services to the ED. METHODS: Using forms supplied by the College of American Pathologists Q-Probes program, participants conducted a self-directed study of ED TAT over a 4-week period. Data requested included various times of day associated with the ordering, specimen collection, laboratory receipt, and result-reporting stages of stat ED TATs for potassium and hemoglobin. Additionally, practice-related questions associated with the laboratory were asked. Participating laboratories also provided a physician satisfaction survey for up to 4 physicians who were users of ED services. Results of both the TAT study and the physician satisfaction survey were returned by mail. Participants were drawn from the 952 hospital laboratories enrolled in the 1998 College of American Pathologists Q-Probes study on ED TAT. The main outcome measures included the components of the ED TAT process, factors associated with decreases in ED TAT, and the results of the physician satisfaction survey. RESULTS: Six hundred ninety hospital laboratories (72.4% response rate) returned data on up to 18 230 hemoglobin and 18 259 potassium specimens. Half of these laboratories responded that 90% of potassium tests were ordered and reported in 69 minutes or less, whereas the TAT for 90% of hemoglobin results was 55 minutes or less. Comparison of the components of TAT for both potassium and hemoglobin with similar studies done in 1990 and 1993 showed no change. Factors found to statistically contribute to faster TATs for both tests were laboratory control of specimen handling and rapid transport time. When whole blood specimens were used for potassium determination, TAT improved. Emergency department physicians chose the study-defined lower satisfaction categories of Often, Sometimes, Rarely, and Never for the questions concerning the laboratory being sensitive to stat testing needs (39.1%) and meeting physician needs (47.6%). Many of the physicians surveyed believed that laboratory TAT caused delayed ED treatment more than 50% of the time (42.9%) and increased ED length of stay more than 50% of the time (61.4%) when compared with other specialty users of the ED. CONCLUSIONS: Laboratory ED TATs have remained unchanged for almost a decade. Emergency department physicians are not satisfied with laboratory services. Although it appears that one issue may relate to the other, the interaction between the laboratory and the ED is quite complex and has been evolving for at least 30 years. Improvement in interoperability between the departments is essential for operational efficiency and patient care. Effective communication channels need to be established to achieve these goals.

Attitude of Health Personnel↗