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At least 523 records · Page 29Linked to original sources
PubMed1982

Total effective time of the forced expirogram in disease: sources of error and a correction factor.

Effective time of the forced expirogram is a sensitive index for the detection of mild airways obstruction. However, there is evidence that this measurement is not superior to maximum flow rates in the lower half of the forced vital capacity or even FEV1 and FEV1% in some patients suffering from obstructive lung disease. Furthermore we noticed that in some patients with a decrease of the forced vital capacity caused by exacerbation of airways obstruction, the effective time was not appreciably changed. We concluded that this apparent disadvantage of the effective time is the result of the different forced vital capacities. To eliminate this error we transformed the forced expirogram to the equivalent curve that the patient would produce, if his forced vital capacity was equal to the predicted mean value for his age, sex, and height. The derived corrected total effective time seems to have increased sensitivity for detection of small changes in expirograms obtained from the same subject or from different subjects.

Asthma↗
PubMed1981

Laboratory diagnosis of Johne's disease: a potential source of error.

Gastrointestinal tract tissues from cattle with suspected clinical Johne's disease (JD), in which acid-fast bacilli were not identified in mucosal smears, were examined histopathologically. Twenty-two per cent were positive and 4 per cent were suggestive of JD. Failure to identify mycobacteria in mucosal smears appeared to result from the presence of mild, often focal mucosal lesions which contained relatively few bacilli. Ten of the 22 histopathologically positive cases had complement fixation titres for JD but several false-positive titres also occurred.

Animals↗
PubMed1979

Photooxidation of NADH by 2,3-butanedione: a potential source of error in studies on active site arginyl residues.

Incubation of NADH or NADPH with 2,3-butanedione in aqueous solution results in photooxidation of the reduced pyridine nucleotides under conditions of ordinary laboratory lighting. Maximum rates of photooxidation are obtained at pH 7 and with light at a wavelength of 410 nm. This reaction could lead to artifactual results in experiments on the role of arginyl groups in enzymes in which a reduced pyridine nucleotide is used to protect the active site residues from modification by 2,3-butanedione.

Arginine↗
PubMed1998

Duplicated superficial femoral veins: a source of error in the sonographic investigation of deep vein thrombosis.

PURPOSE: To determine whether the number of false-negative ultrasound (US) findings of thrombosis is larger when a duplicated femoropopliteal venous system is present. MATERIALS AND METHODS: A retrospective review was performed of 381 venograms obtained after initial US findings were considered negative for thigh or popliteal thrombosis in patients in whom deep vein thrombosis was suspected Venograms were evaluated for the presence of thrombosis and the presence and configuration of duplicated superficial femoral veins. RESULTS: Multiple superficial femoral veins were present on 177 (46%) of the 381 venograms; 149 (84%) were duplex systems. False-negative US findings occurred in four (2%) of 204 patients with single femoral veins and in 10 (6%) of 177 patients with duplicated femoral veins (P = .056, not statistically significant). CONCLUSION: The frequency of missed proximal thrombosis at sonography appears to be increased when duplicated superficial femoral veins are present. Data from clinical and imaging studies are insufficient to support the adoption of a totally noninvasive imaging strategy.

Congenital Abnormalities↗