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June 1, 2005
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Educational activities are a background to research and to a dynamic, developing discipline. The principles now being applied in undergraduate curricula are applicable to teaching and training in laboratory medicine. A fresh look at the education and training and an implementation of new educational techniques is necessary to prepare a cadre of individuals who will be developing laboratory medicine in the 21st century.
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June 1, 2005
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Two reverse transcription-polymerase chain reaction methods to detect the AML1/ETO rearrangement in the M2 subtype of acute myeloid leukaemia those of Downing et al. (Blood 1993; 81:2860–5) and Satake et al. (Br J Haematol 1995; 91:892–8) were evaluated. Bone marrow samples, one at diagnosis and two in complete remission from a patient with M2 subtype of acute myeloid leukaemia, with t(8;21), were analysed using both methods. The Kasumi-1 cell line was used as a positive control and a patient with M3 subtype of acute myeloid leukaemia as a negative control. To confirm the feasibility of Satake's method a group of 35 patients with subtypes of acute myeloid leukaemia at diagnosis were studied. The method of Downing requires Southern blotting and hybridization with a specific probe because it often generates non-specific amplification products. By contrast, the method of Satake yields only a single amplification product, using one single round of PCR in samples at diagnosis, or two rounds in complete remission samples. The sensitivity of this method allows the detection of a single Kasumi-1 cell in 10 6 normal cells. The AML1/ETO rearrangement was observed in 5 of the 35 cases of acute myeloid leukaemia at diagnosis (14.3%) and in 3 of the 14 cases of M2 subtype of acute myeloid leukaemia (21.4%). The two remaining positive cases corresponded to the acute myeloid leukaemia subtypes M4 and M6. The results indicate that the method of Satake better meets the requirements of the clinical laboratory due to its greater simplicity, specificity, sensitivity and feasibility, thus making it more appropriate for use in diagnosing and monitoring minimal residual disease.
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June 1, 2005
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The present study was undertaken to determine the effect of ingestion of large doses of vitamin C on urinary oxalate excretion and on a number of other biochemical and physicochemical risk factors associated with calcium oxalate urolithiasis. A further objective was to determine urinary ascorbate excretion and to relate it qualitatively to ingested levels of the vitamin and oxalate excretion. Ten healthy males participated in a protocol in which 4 g ascorbic acid was ingested for 5 days. Urines (24 h) were collected prior to, during and after the protocol. The urine collection procedure was designed to allow for the analysis of oxalate in the presence and absence of an EDTA preservative and for the analysis of ascorbic acid by manual titration using 2,6 dichlorophenolindophenol. Physicochemical risk factors such as the calcium oxalate relative supersaturation and Tiselius risk index were calculated from urine composition. The results showed that erroneously high analytical oxalate levels occur in the asence of preservative. In the preserved samples there was no significant increase in oxalate excretion at any stage of the protocol. Ascorbate excretion increased when vitamin C ingestion commenced but levelled out after 24 hours suggesting that saturation of the metabolic pool is reached within 24 hours after which ingested ascorbic acid is excreted unmetabolized in the urine. While transient statistically significant changes occurred in some of the biochemical risk factors, they were not regarded as being clinically significant. There were no changes in either the calcium oxalate relative supersaturation or Tiselius risk index. It is concluded that ingestion of large doses of ascorbic acid does not affect the principal risk factors associated with calcium oxalate kidney stone formation.
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June 1, 2005
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Patients with chronic renal failure, and particularly those receiving regular haemodialysis, have a high incidence of premature cardiovascular disease. Oxidative stress, which causes lipid peroxidation, may contribute to increase the risk of atherosclerosis. The results of the present study indicate that lipid peroxidation products (malonaldehyde and 4-hydroxyalkenals) are significantly increased in plasma of renal patients before dialysis and, although reduced, remained above the normal range after this treatment. Moreover, production of free radicals and reactive oxygen metabolites was increased in chronic renal failure patients, especially after dialysis. On the other hand, the antioxidant defenses of those patients were higher than those of normal subjects, as judged from the plasma levels of specific antioxidant molecules and from the plasma antioxidant capacity. We also found that triglycerides were significantly higher in renal patients, both before and after dialysis, than in the control group. These results suggest that patients on chronic haemodialysis are particularly prone to oxidative stress and that dialysis itself may worsen this condition. Rather than to a weakening of antioxidant defenses, the susceptibility of chronic renal failure patients to oxidative stress might be ascribed to an increased free radical and reactive oxygen metabolite production and to increased levels of oxidizable substrates, notably triglycerides with their unsaturated fatty acids.
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June 1, 2005
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The mechanism of action of non-steroidal anti-inflammatory drugs which are used in high doses in chronic inflammatory conditions is not clearly understood. Their known protein-stabilizing properties could play a significant role. The inhibition of cyclooxygenase may not be essential for their anti-rheumatic activity, since compounds with strong anti-denaturant properties and devoid of anti-inflammatory activity were shown to be effective in an experimental model of rheumatoid arthritis. Hence, to develop new anti-rheumatic drugs it is essential that a simple in vitro method to evaluate the anti-denaturant activity of endogenous and exogenous compounds is available. We developed a new assay, using gel permeation high performance liquid chromatography, to study the effect of endogenous and exogenous compounds on heat-induced aggregation of human serum albumin in conditions in which protein precipitation does not occur. Non-steroidal anti-inflammatory drugs like diclofenac, ibuprofen and naproxen inhibited the aggregation of albumin at low concentrations (EC 50 10 −4 –10 −5 mol/l) comparable to those active in a classical turbidimetric method, whereas the effect of weak stabilizers, like sodium cloride and formic, fumaric, maleic, malonic, and succinic acid (EC 50 10 −1 –10 −2 mol/l in the Mizushima test) was not detectable. Furthermore, the HPLC assay allowed the examination of a number of coloured substances, including bilirubin, which appeared to be a strong stabilizer of its physiological carrier, albumin. These data could be clinically relevant, since the drugs examined are used at very high doses in rheumatoid arthritis and related conditions, with plasma levels that could cause significant stabilization of serum albumin and perhaps other proteins.
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June 1, 2005
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The aim of the study was to measure serum levels of the bone-specific isoenzyme of alkaline phosphatase in normal subjects and patients with metabolic bone disease by using an immunoadsorption assay. We studied 140 healthy adults, 122 patients affected by metabolic bone disease and 15 patients with cholestatic liver disease. Mean values of the bone-specific isoenzyme of alkaline phosphatase in healthy men were significantly higher than those found in premenopausal women (17.8 ± 4.2 U/l vs 15.6 ± 4.6 U/l, p<0.02); postmenopausal women had significantly higher levels of bone-specific isoenzyme of alkaline phosphatase (22.6 ± 6.4 U/l) than premenopausal women (p<0.0001). After the menopause total alkaline phosphatase increased by 46 %, while the increase in bone-specific isoenzyme of alkaline phosphatase was 39 %. No significant correlations were found between bone-specific isoenzyme of alkaline phosphatase and either age or years since menopause, in postmenopausal subjects. In patients with bone-specific isoenzyme of alkaline phosphatase above the upper limit of normal, the assay had a sensitivity of 100 % only in patients with Paget's disease of bone. In patients with cholestatic liver disease we found no correlation between bone-specific isoenzyme of alkaline phosphatase and either total alkaline phosphatase and γ-glutamyl transpeptidase, while a positive correlation was found between total alkaline phosphatase and γ-glutamyl transpeptidase. Our results confirm the role of bone-specific isoenzyme of alkaline phosphatase assay in clinical research; however, its usefulness in clinical practice is unclear once liver involvement has been excluded.
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June 1, 2005
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Serum β 2 -microglobulin, neopterin, immunoglobulins A, G and M, adenosine deaminase and CD4+ lymphocyte count were evaluated as predictors of progression of HIV-1 infection to AIDS. A population of HIV-1 seropositive, initially asymptomatic men (n=213) and women (n=101) was followed up quarterly. We estimated the AIDS-free time using the actuarial method (median survival time 47.2 months). Cox proportional hazard analysis revealed that all markers studied were significant (p<0.05) in relation to progression to AIDS. The best markers for predicting progression to AIDS were, in descending order, CD4+ lymphocyte count, β 2 -microglobulin, IgA, neopterin, IgG, IgM and adenosine deaminase. On stratifying population into four groups (devided at percentiles 25, 50 and 75—from group 1, with values nearest to reference ranges, to group 4, with most abnormal values) we observed statistically significant differences (p<0.05) for all markers except for adenosine deaminase. The relative risk from the Cox proportional hazards model were used to quantify the effects of the best markers and compared to the risk obtained in group 1. CD4+ lymphocyte count was the best predictor of progression to AIDS. When considering β 2 -microglobulin and CD4+ together, the relative risk in the group with lowest CD4+ cell count (group 4) ranged from 25.6% (with lower β 2 -microglobulin values) to 41.1% (with higher β 2 -microglobulin values). Similar results were obtained when considering neopterin and CD4+ together. The addition of β 2 -microglobulin or neopterin values to CD4+ lymphocyte count improved the predictive value of CD4+ lymphocyte count.
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June 1, 2005
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One of the main determinants of plasma homocysteine in healthy subjects is serum creatinine. In the present study, we therefore investigated the relation between plasma homocysteine concentration, serum creatinine and a new marker for glomerular filtration rate, plasma cystatin C concentration. Cystatin C reflects the glomerular filtration better than serum creatinine and is not related to the muscle mass and formation of creatinine. The study group consisted of 255 healthy subjects from a well-defined area in the southern part of Sweden. The concentration of plasma homocysteine was increased in men compared to women. This difference disappeared when men and women were stratified by serum creatinine values. Statistically significant correlations were noted between plasma homocysteine and age, plasma cystatin C and serum creatinine. It is shown that plasma homocysteine is not only correlated to serum creatinine as a result of renal function but also as a result of the relationship between homocysteine production and creatine-creatinine synthesis. Using linear regression we were able to show that plasma cystatin C had a higher explanatory value than age. Serum creatinine showed a lower explanatory power than age. The findings in the present study might suggest that the increase of plasma homocysteine concentration with age could be partly due to the deterioration of renal function. Study
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June 1, 2005
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Many efforts have been made to find valuable serum tumour markers which help the diagnosis of pancreatic cancer. In the present study we investigated the diagnostic value of CA 242 in comparison with two other routinely used tumour markers (CA 19–9 and CA 50). Two-hundred and seventy six subjects were enrolled in this study: 46 patients with pancreatic cancer preoperatively, 53 with chronic pancreatitis, 28 with acute pancreatitis, 49 with other malignancies, 50 with miscellaneous non-neoplastic digestive diseases, and 50 healthy subjects. CA 242 was determined in serum by means of a two-step fluoroimmunometric assay. Sensitivities of CA 242, CA 19–9 and CA 50 for pancreatic cancer when all patients were considered were 41.3%, 54.3% and 47.8%, respectively (95% specificity level). No significant improvement was achieved by combination of CA 242 with CA 19–9 and/or CA 50. Cholestasis affected serum levels of CA 242 in patients without pancreatic cancer, but not in those with this tumour. The metastatic stage of pancreatic cancer appeared to influence the levels of CA 242. In conclusion, CA 242 serum assay does not seem to improve diagnostic accuracy for pancreatic cancer compared to CA 19–9 and CA 50.
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June 1, 2005
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July 27, 2005
