Evaluation of the automated 'Enzymen-Test Anti HIV-1 + 2' and 'Enzymen-Test Anti HIV-1/2 selective' for the combined detection and differentiation of anti-HIV-1 and anti-HIV-2 antibodies.

A new, modular automated ELISA (test 1) for HIV-1 and HIV-2 antibody detection and differentiation (Enzymun-Test Anti HIV-1 + 2; anti HIV 1/2 selective, Boehringer Mannheim) was compared with 3 alternative enzyme immunoassays (Abbott recombinant HIV-1/HIV-2 3rd generation EIA, Abbott (test 2); Enzygnost HIV 1 + 2, Behringwerke (test 3); and Wellcozyme HIV recombinant, Murex (test 4)) and Western blot (New LAV I Blot and New LAV II Blot; Diagnostics Pasteur). 380 serum samples from HIV-1 and HIV-2 seropositive patients at different stages of disease, high risk individuals, patients with conditions unrelated to AIDS and from healthy blood donors were used in this evaluation along with 6 seroconversion panels, 6 serum dilution series and 'tricky' sera (repeatedly positive results in ELISA, but negative or undeterminate in Western blot; n = 67). Using the Western blot as reference assay, the overall sensitivity of the four ELISAs was 100%. Test 4 showed the highest sensitivity for antibody detection in seroconversion and dilution series. A high specificity was achieved with test 1 (100%) and test 2 (99.4%). A relatively high rate of false positive results were obtained with test 2 (n = 12) and test 3 (n = 10) by testing 'tricky' sera or samples obtained from healthy blood donors. In comparison to Western blot, a clear differentiation between HIV-1 and HIV-2 antibody serum samples was achieved with the Enzymun-Test. The results of the present study show that the Enzymun-Test provides reliable selective HIV-1 and HIV-2 antibody detection at a cost which is significantly lower than the costs of Western blot tests. Furthermore, the evaluation of test 1 suggests, that it is a highly specific assay for HIV antibody detection.

[The evaluation of dry chemical laboratory methods. Their value within the framework of step-by-step diagnosis in general medicine]. / Bewertung trockenchemischer Labormethoden. Stellenwert im Rahmen der Stufendiagnostik in der Allgemeinmedizin.

In a prospective study involving eleven general practices, dry-chemical laboratory methods were compared with wet-chemical methods in the establishment of the diagnosis. The study included 658 patients in whom defined liver disease, lipid metabolic disturbances, diabetes mellitus or hyperuricemia were clinically suspected. In the "dry chemistry" group, between 12 and 29% fewer basic examinations (ESR, Hb, erythrocytes, leukocytes) were performed than in the "wet chemistry" group. In addition the number of analyses per patient in the so-called search program and among the subsequently requested laboratory analyses were also lower by about 21% in the "dry chemistry" group. This indicates that through the use of "dry chemistry", laboratory examinations can be used with greater selectivity. A further advantage of "dry chemistry" is the appreciably shorter time required to establish and report the diagnosis.

8-Azidoacenine analogs of NAD+ and FAD. Synthesis and coenzyme properties with NAD+-dependent and FAD-dependent enzymes.

The synthesis and purification of the 8-azidoadenine analogs of NAD+ (azido-NAD+) and FAD (AZIDO-FAD) from 8-azidoadenosine 5'-phosphate and NMN+ or FMN, respectively, is described. The coenzyme analogs are characterized by absorption, nuclear magnetic resonance and circular dichroism spectra. The two latter methods indicate a folded structure of azido-NAD+ and azido-FAD. Upon irradiation at 300 mn in aqueous solution, a change of the ultraviolet absorption spectra of the coenzyme analogs indicates photolysis of the azido group. The coenzyme properties of azido-NAD+ are demonstrated with lactate, glutamate and alcohol dehydrogenase yielding 14, 154 and 60%, respectively, of the V observed with NAD+. Concomitantly, the Km values of the coenzyme analogs are 1.7, 3.5 and 3-fold higher than those of NAD+. Azido-FAD is shown to be coenzyme of apo-glucose oxidase. The recovery of activity, however, is much slower in the presence of azido-FAD than with FAD. A final value of 66% of the activity with FAD is obtained. With apo-D-amino acid oxidase, azido-FAD is completely inactive, although it is specifically bound to the enzyme.

Effects of heterogeneous myocardial perfusion on coronary venous H2 desaturation curves and calculations of coronary flow.

The present investigation was intended to evaluate myocardial inert gas desaturation curves for manifestations of heterogeneous coronary perfusion. The test gas was hydrogen (H(2)) and blood H(2) analyses were performed with a gas chromatograph capable of detecting small but prolonged venous-arterial H(2) differences produced by areas of reduced flow. Curves were initially obtained after 4-min left ventricular infusions of H(2)-saturated saline in six patients with arteriographically proven coronary artery disease, three patients with normal coronary arteries, and nine closed-chest dogs. The dogs were studied before and after embolic occlusion of a portion of the left coronary artery. Although the slopes of their semilogarithmically plotted venous desaturation curves varied with time before embolization, they showed more distinct deviations from single exponentials after embolization (after H(2) concentrations had fallen below 15% of their initial values). The human curves divided similarly, those from coronary artery patients deviating appreciably from single exponentials. A similar separation was also evident in studies of coronary venous-arterial H(2) differences after 20 min of breathing 2% H(2): data were obtained in four dogs before and after coronary embolization, and in three normal patients, and five patients with coronary artery disease. Additional data indicated that the findings were not the result of right atrial admixture in sampled coronary venous blood, although admixture occurred frequently when blood was sampled in the first 2 cm of the coronary sinus (as seen in the frontal projection). Finally, average coronary flows calculated from a given set of data varied significantly with different methods of calculation. Areas of below-average flow seemed likely to be overlooked when single rate constants of desaturation, relatively insensitive analytical techniques, or relatively short periods of saturation and (or) desaturation are employed.