Evaluation of the Beckman Coulter DxC 700 AU chemistry analyzer

OBJECTIVES

We evaluated and defined the analytical performance of the Beckman Coulter DxC 700 AU analyzer compared to the Siemens Dimension Vista 500 analyzer.

DESIGN

and Methods: Performance characteristics included intra and inter-run precision, linearity/analytical measurement range, method correlation, and reference range verification. A total of 53 assays including 11 critical care, 19 general chemistries, 11 proteins, 10 urines, and 2 CSF analytes were tested. We also evaluated similarities and differences in assay methodologies between the 2 systems.

RESULTS

The DxC 700 AU demonstrated excellent precision, comparable analytical measurement ranges and strong method correlation with the Dimension Vista 500 for most serum/plasma assays. 95% of the intra-run and 95% of the inter-run precision QC levels showed <3.0%CV and <6.0%CV, respectively. None of the deviations were clinically significant. The AMRs for all analytes except 5 met the manufacturer's stated range. ALP, Lactate, U-glucose and CSF-glucose all recovered above the stated upper limit range, while prealbumin showed a smaller range. All analytes, except 14, showed slopes between 0.9 and 1.1 and/or biases <10%. Only ammonia, ferritin and lipase required significant reference range changes. The urine and CSF assays correlated very well with no adjustments in reference ranges required.

CONCLUSIONS

The analytical performance of the DxC 700 AU analyzer was acceptable with only a small number of analytes requiring significant reference range changes.

Stability of Therapeutic Drugs in Serum Collected in Vacutainer Serum Separator Tubes Containing a New Gel (SST II)

The stability of therapeutic drugs in sera collected in Becton-Dickinson Vacutainer serum separator SST tubes has been well studied. Although most therapeutic drugs are stable, certain drugs such as phenytoin, carbamazepine, and phenobarbital decrease in concentrations over a long storage time. To circumvent this problem, Becton-Dickinson devised a new gel formulation. The authors studied the stability of 14 commonly monitored drugs in sera when stored on the new gel of the SST II tubes and compared the concentrations of drugs in sera stored in plain tubes (no gel), those stored in the old SST tubes, and those stored in the SST II tubes containing a new serum separator gel. The concentrations of most drugs studied did not decline even after 24 hours of storage in SST II tubes. After storage for 7 days in SST II tubes, the concentration of carbamazepine declined by 10% and that of phenytoin decreased by 4%. This is a significant improvement over the existing tube, where concentrations of several drugs declined with prolonged storage. The authors conclude that new SST II tubes are effective in collecting blood for therapeutic drug monitoring.

SPET of a computerised model of diffuse lung disease

Emphysema is a common and debilitating disease that is the commonest cause of end-stage respiratory failure. Treatment is either by lung transplantation or by lung volume reduction surgery (LVRS) that improves the biomechanics of respiration. Patient selection for LVRS hinges on the demonstration of heterogeneous disease, predominantly involving the upper lobes, as a good surgical outcome is most likely in these patients. We used a virtual model of lung scintigraphy to compare planar with tomographic scintigraphy for the detection of diffuse lung disease. Lesions of the magnitude of the lung acinus, as well as larger and smaller lesions, were distributed throughout the lungs in volumes from 2% to 50%. Single-photon emission tomography does not add incremental value to planar images for the detection of diffuse lung disease.

Single-photon emission tomography of a computerised model of pulmonary embolism

Planar pulmonary scintigraphy is currently the standard investigation for the diagnosis of pulmonary embolism. There are a number of problems with the technique, particularly in patients with an intermediate scan report under the PIOPED criteria. The technique is also under threat from the increasing use of spiral CT angiography. A putative improvement may be gained by use of tomography. The incremental value of tomography over planar studies was therefore evaluated in a virtual model of pulmonary scintigraphy. A model of the segmental anatomy of the lungs was developed from computed tomography, cadaveric human lungs and available anatomical texts. Counts were generated within the phantom by Monte Carlo simulation of photon emission. Eighteen single segmental lesions were interspersed with 47 subsegmental defects and displayed on an Icon reporting station. These were presented in the transaxial, sagittal and coronal planes to four experienced reporters to obtain assessment of defect size. Planar studies of the same defects were displayed to the same observers in the standard eight views with a normal study for comparison. With planar studies, the accuracy of estimation of defect size was 51% compared with 97% using tomographic studies. Defects in the medial basal segment of the right lower lobe were not identified in planar studies but were easily seen by all observers in the tomographic study. It is concluded that there is marked improvement in the accuracy of determination of defect size for tomographic studies over the planar equivalents. This is especially important in the lung bases, the most common reported site of pulmonary emboli. Tomography permits visualisation of defects in the medial basal segment of the right lung, which are not seen in planar studies.

A quality tool for health insurers. A new scale measures "quality orientation" from the customer's point of view

This study defines a company's quality orientation as "all process-related activities that can be discerned by customers." This even includes certain processes internal to the company that can be seen and evaluated by customers. One significant contribution this study provides is scale development centered on customer rather than employee perceptions. To generate scale items, input was gathered from experts involved in the study, senior managers employed with the target company, focus groups of employees working on the front line with customers, and users of the services. Because the sale measures customer perceptions of quality in comparison with the firm's closest competitor, it provides managers with information for benchmarking performance relative to others in the marketplace.

Physical properties and use of pertechnegas as a ventilation agent

Pertechnegas, a variant of technegas, produces similar ventilation images with a much increased clearance rate. This work aims to determine the properties of pertechnegas and its use as a ventilatory agent.

METHODS

Fourteen men and 11 women were scanned for PE, after pertechnegas ventilation. Six were reimaged with technegas within 1 wk. Studies were reported according to PIOPED criteria. Pertechnegas samples were analyzed by transmission electron microscopy (TEM), cascade impaction (CI), aerosol mobility analysis (AMA), Fourier transform mass spectrometry (FTMS), x-ray photoelectron spectroscopy (XPS), paper strip (PC) and gas chromatography (GC).

RESULTS

Post-test probabilities were normal in 5, low in 8, high in 5 and indeterminate in 7. There were 15 Grade 1, 6 Grade 2 and 4 Grade 3 studies. All Grade 3 patients had FEV1 < 1.5 liters, 3 with rates < 1.0 liter. Patients with high probability had proven deep venous thrombosis in three by venography and in one by doppler. TEM identified 0.3 micron salt particles. CI demonstrated a 7-min time to half clearance from the chamber for particles in the < 0.1 micron range. AMA indicated all particles were < 0.032 micron when salt was excluded. Pertechnegas behaves in PC as pertechnetate, GC demonstrated CO levels below 516 ppm. CO2 concentrations were 0.146 +/- 0.0009%. FTMS found molecular pertechnetate species including 99TcO3(OH)+, Na99TcO3(OH)3+ and Na99TcO3(OH)3+. XPS confirmed that these Tc species exist in oxidation state +7.

CONCLUSION

Comparison with technegas images in the follow-up group proved equivalent in the first five views, but indistinct lung boundaries and a high background activity characterized the final anterior images. The active component of pertechnegas is molecular pertechnetate.

Guamanian neurodegenerative disease: investigation of the calcium metabolism/heavy metal hypothesis

OBJECTIVE

There is a high prevalence of neurodegenerative disease (parkinsonism, dementia, and motor neuron disease) on the western Pacific island of Guam. We sought evidence in support of the hypothesis that these conditions are triggered by nutritional deficiencies of calcium and magnesium leading to secondary hyperparathyroidism that then facilitates the entry of calcium and toxic heavy metals into the brain.

METHODS

We analyzed indices of calcium metabolism plus blood-serum, urine, nail, and hair heavy metal concentrations in 12 patients with Guamanian neurodegenerative disease and 12 Chamorro control subjects.

RESULTS

All 12 patients with Guamanian neurodegenerative disease had normal values for serum total and ionized calcium, 25-hydroxyvitamin D, and 24-hour urine collections for calcium. Eleven of 12 patients had normal serum parathyroid hormone values and alkaline phosphatase levels. No patient had reduced serum phosphorus or magnesium values although a minority of patients and controls had low urinary magnesium concentrations. Median blood-serum and 24-hour urine collections for heavy metals (aluminum, arsenic, cadmium, copper, iron, lead, manganese, mercury, and zinc) were statistically similar in the patient and control groups except for a slight elevation of blood, but not urine, lead in the patient group. Concentrations of heavy metals in hair and nails were similar in the two groups.

CONCLUSIONS

We could find no evidence in support of abnormalities of calcium metabolism or heavy metal absorption as a major causative factor in the development of neurodegenerative disease on the island of Guam.

[Ciprofloxacin and other antimicrobial drugs in the treatment of disseminated peritonitis]

Forty two patients with general peritonitis were treated with ciprofloxacin and combinations of various antimicrobial drugs. Ciprofloxacin had the highest effect on aerobic and anaerobic microbes in the peritoneal cavity which defined the favourable clinical results in all the patients. Moreover, there were observed no disorders in the composition of the normal intestinal microflora which in the end promoted a decrease in the number of the patients with suppuration of the surgical wound.

[Selective decontamination of the intestine and total gnotobiologic isolation in treatment of mice with acute radiation sickness]

Comparative study of ciprofloxacin, pefloxacin and amikacin showed that ciprofloxacin and pefloxacin had a selective action on the intestinal microflora of conventional mice. Amikacin induced inhibition not only of the opportunistic bacteria but also of the representatives of the indigenous microflora. The use of the drugs in combination with total gnotobiological isolation in treatment of experimental radiation sickness provided an increase in survival of the irradiated animals, the more so as ciprofloxacin was used.

Management and autopsy of a radioactive cadaver

A 69 year old male was treated with an ablative dose of 3.7 GBq (100 mCi) of I131 for carcinoma of the thyroid and died 10 days after administration. The requirement for an autopsy and the level of radiation still present in the body necessitated the intervention of Radiation Safety Personnel to minimise support staff radiation exposure and area contamination. Preventative measures were taken in accordance with the ALARA principle and a detailed procedure is presented as a suggested model for any future occurrence.

Bromcresol purple dye-binding methods underestimate albumin that is carrying covalently bound bilirubin

We used automated and manual versions of two commonly used dye-binding methods for albumin to quantify albumin that had been modified by covalent addition of bilirubin. Dye-binding methods based on reaction with bromcresol purple underestimated the modified albumin by as much as 29%. Dye-binding methods based on reaction with bromcresol green were unaffected by the presence of covalently attached bilirubin. Neither method was affected by the presence of noncovalently bound bilirubin.

Bromcresol purple dye-binding methods underestimate albumin that is carrying covalently bound bilirubin

We used automated and manual versions of two commonly used dye-binding methods for albumin to quantify albumin that had been modified by covalent addition of bilirubin. Dye-binding methods based on reaction with bromcresol purple underestimated the modified albumin by as much as 29%. Dye-binding methods based on reaction with bromcresol green were unaffected by the presence of covalently attached bilirubin. Neither method was affected by the presence of noncovalently bound bilirubin.

An electron microscope study of the intercellular contacts between the erythroblasts of patients with hypersiderotic bone marrows

When stained and unstained sections of hypersiderotic marrow fragments are examined in the electron microscope, some of the ferritin molecules present between a variable proportion of the erythroblasts are found to be aligned more or less transversely. These linearly arranged ferritin molecules are particularly evident in regions in which the opposing cell membranes have been sectioned obliquely and may be confused with the septa-containing intercellular junctions characteristically present between some types of invertebrate epithelial cells.

An investigation into the development and fate of neutrophil giant metamyelocytes using the techniques of electron microscopy and high resolution autoradiography

The neutrophil giant metamyelocytes present in vitamin B12-and folate-deficient patients were studied using the techniques of electron microscopy and electron microscope autoradiography. The ultrastructural features of the cytoplasm of a proportion of these cells resembled those of promyelocytes and myelocytes, particularly with respect to the types of neutrophil granules present. This finding suggests that the giant metamyelocytes result from an abnormal type of development in promyelocytes and myelocytes which have been arrested or retarded in their progress through the cell cycle. The hypothesis that giant metamyelocytes eventually die within the marrow was supported by the observations that a significant proportion of these cells contain intracytoplasmic autophagic vacuoles, that some giant metamyelocytes suffer from a marked depression of RNA and protein synthesis and that degenerating giant metamyelocytes can be recognized within the cytoplasm of some bone marrow macrophages.

Electron microscope and high resolution autoradiographic studies of megaloblastic erythropoiesis

Bone marrow fragments from 10 patients with a megaloblastic anaemia due to vitamin B12 or folate deficiency were studied by electron microscopy and electron microscope autoradiography. A proportion of the erythroblasts showed ultrastructural abnormalities. Some of the cells containing autophagic vacuoles, large siderosomes, iron-laden mitochondria, irregularly shaped nuclei, membrane-bound nuclear clefts, or incomplete nuclear membranes were found to be capable of DNA, RNA and protein synthesis. Other cells showed advanced degenerative changes such as the distension of the perinuclear space, the clumping of cytoplasmic organelles near the nucleus and a reduction in the electron density and ribosome content of the cytoplasm. Most of these grossly abnormal cells suffered from either a marked depression or an arrest in protein and RNA synthesis, and were presumably destined for phagocytosis by reticulum cells.

Observations on the ultrastructure of erythropoietic cells and reticulum cells in the bone marrow of patients with homozygous beta-thalassaemia

An electron microscopic study of marrow fragments from patients with homozygous beta-thalassaemia has shown that 3% of early polychromatic erythroblast profiles and 20% of late polychromatic erythroblast profiles contain intracytoplasmic alpha-chain precipitates. Various nuclear abnormalities were found including the loss of parts of the nuclear membrane and the presence of intranuclear alpha-chain precipitates, and these abnormalities were virtually confined to the non-dividing, late polychromatic erythroblasts. As most profiles of the proliferating early polychromatic erythroblasts did not contain intracytoplasmic or intranuclear alpha-chain precipitates, it is suggested that the arrest of many of these cells in the G1 phase of the cell cycle may be related to the presence of an excess of free alpha-chains rather than to the presence of alpha-chain precipitates within them. The cytoplasm of the bone marrow reticulum cells contained early and late polychromatic erythroblasts at various stages of degradation, providing direct evidence of ineffective erythropoiesis.