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Biomedical subjects

C M Yu

Publications and source records attributed to C M Yu.

63 records · Page 4Linked to original sources
PubMed1989

Detection of mycobacterial antigens in cerebrospinal fluid by enzyme-linked immunosorbent assay utilizing anti-mycobacterial saline extract antibodies.

Using anti-mycobacterial saline extract antibodies, Mycobacterium tuberculosis antigens can be detected in cerebrospinal fluid by a highly specific and sensitive double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). The ELISA was dose-dependent and capable of detecting as little as 6.0 ng of antigens. Specificity was demonstrated by negative results (0.063 +/- 0.008) with other bacterial and cryptococcal antigens (n = 9), and maximum cross-reactivity with other mycobacteria was less than 2.0%. Absorbance for six patients with confirmed tuberculous meningitis gave results ranging from 0.168 to 0.898 with a mean value of 0.393 +/- 0.248. For 172 nonmeningitis and nontuberculosis control patients and 6 treated tuberculous meningitis patients, optical densities were 0.064 +/- 0.001 and 0.057 +/- 0.007, respectively. Significant statistical difference (p less than 0.001) was found between the tuberculous meningitis and control groups.

Animals↗
PubMed1980

Role of divalent cations and ascorbate in photochemical activitis of Anacystis membranes.

Photosynthetic membrane fragments were prepared from Anacystic nidulans by French pressure cell disruption. Ascorbate was required to stabilize photophosphorylation activity in membranes kept at near 0 degrees C. Divalent cations were required during mechanical disruption and during assays for Photosystem II activity, with Ca2+ serving best. The rate of photophosphorylation was severely inhibited by Ca2+ during assays. Results suggest that best rates are achieved when photosynthetic membranes contain Ca2+ exposed to the interior surface, facilitating Photosystem II activity, and Mg2+ exposed to the exterior surface during assays, facilitating photophosphorylation activity.

Calcium↗
PubMedDate not supplied

Synergy assessed by checkerboard. A critical analysis.

The checkerboard dilution test is widely used for evaluation of in vitro synergy for multiple drugs, although problems in performance, standardization, and interpretation have been noted. A major problem inherent in this commonly used method is the use of twofold dilutions for the antibiotic concentrations. We evaluated an alternative method proposed by Horrevorts and colleagues that preserved the twofold dilution scheme. Giant checkerboards were constructed from a series of component checkerboards using rifampin and minocycline against Staphylococcus aureus. We found that this method improved the stability of the fractional inhibitory concentration (FIC) indices, but required substantially more labor and generated other problems. FIC interpretation and calculation remained compromised by the twofold dilution scheme. We have analyzed the theoretical basis of the checkerboard and its FIC calculation and conclude that the twofold dilution with its exponential increase in dilutions makes this method of synergy evaluation inherently unstable. The principle of examining growth at multiple dilutions of combined antibiotics is valid for assessment of synergy, but newer methods need to be devised.

Drug Synergism↗