[Establishment of standard strains of serotypes (groups) of Streptococcus pneumoniae in China]

Streptococcus pneumoniae is an important human pathogen which is responsible for life-threatening infections such as pneumonia, bacteremia and meningitis as well as for less severe but highly prevalent diseases such as otitis media and sinusitis. The number of serogroups (types) of Streptococcus pneumoniae found in the world is total 46 groups or 83 types according to typing system of Statens Serum Institute, Copenhagen, Denmark. The standard strains established in our lab of 42 groups or 67 types distributed in 17 different regions in China. The significance of this study is that two of the new serotypes (10C, 16A) are first reported in the literature in which the microbes were the agents causing pneumococcal infections. Our standard strains also include some serotypes on rare occasions such as 19C and 22A and 33C which have been found only in Asia. Our findings not only increase the total number of known types of pneumococci from 83 to 85, but also indicate that China has made progress in the field of pneumococcal research. It is the first time to report establishing a series of standard strains of pneumococci involving many serotypes (groups) in China. The work is necessary as a preliminary for pneumococcal disease prevention and treatment. The standard strains listed here with providing the resource of strain and scientific basis for developing vaccine and biological products.

The role of fructose 2,6-bisphosphate in glycolytic oscillations in extracts and cells of Saccharomyces cerevisiae

Fructose 2,6-bisphosphate is physiologically one of the most potent activators of yeast 6-phosphofructo-1-kinase. The glycolytic oscillation observed in cell-free cytoplasmic extracts of the yeast Saccharomyces cerevisiae responds to the addition of fructose 2,6-bisphosphate in micromolar concentrations by showing a pronounced decrease of both the amplitude and the period. The oscillations can be suppressed completely by 10 microM and above of this activator but recovers almost fully (95%) to the unperturbed state after 3 h. Fructose 2,6-bisphosphate shifts the phases of the oscillations by a maximal +/- 60 degrees. Oscillations in concentration of endogenous fructose 2,6-bisphosphate in the extract were also observed. Fructose 2,6-bisphosphate alters the dynamic properties of 6-phosphofructo-1-kinase which are vital for its role as the 'oscillophore'. However, the minute amount (approximately 0.3 microM) of endogenous fructose 2,6-bisphosphate and the phase relationship of its oscillations compared with other metabolites indicate that this activator is not an essential component of the oscillatory mechanism. Further support for this conclusion is the observation of sustained oscillations in both the extracts and a population of intact cells of a mutant strain (YFA) of S. cerevisiae with no detectable fructose 2,6-bisphosphate (less than 5 nM).

[Bioelectric potentials of bone in experimental fracture healing]

A specific electric potential gradient exists on the surface of long bone and the electric gradient changes after fracture. The electric potentials at the fracture site were measured and it was shown to change most actively during the early healing phase, and thereafter reached the normal level gradually. When soft tissue was damaged, certain potential changes occurred. But this change was different from that in the fracture site, indicating that the tissue has "biological window" effect of electrization.

Gas phase ligand substitution reactions in fast atom bombardment mass spectrometry: effects of ligand base strength and choice of matrix liquid in substitution reactions of difluoroborn cations

Strongly basic amidine and guanidine ligands displace weaker-base ligands such as pyridine from D2BF2+ complexes in the gas phase in Fast Atom Bombardment mass spectrometry. The choice of protic vs. aprotic matrix liquid inhibits or promotes gas phase ligand substitution reactions. Keywords: ligand substitution, difluoroboron cations, FABMS.

Immediate converting-enzyme inhibition with intravenous enalapril in chronic congestive heart failure

To test the hypothesis that intravenous enalapril is a useful pharmacologic probe of the renin angiotensin system, intravenous enalapril was administered to 9 patients with severe congestive heart failure (CHF). This produced abrupt and complete blockade of converting enzyme, with peak effect occurring at 30 minutes, as reflected by increases of plasma renin activity (from 16.8 +/- 6 to 86.6 +/- 23 ng/ml/hour) and decreases of plasma aldosterone levels (from 46 +/- 14 to 25 +/- 6 ng%) (both p less than 0.05). With reduction of angiotensin II--mediated vasoconstriction, systemic vascular resistance decreased markedly (from 1,974 +/- 233 to 1,400 +/- 136 dyne s cm-5) and cardiac index was improved (from 1.88 +/- 0.9 to 2.20 +/- 0.21 liters/min/m2) (both p less than 0.05). The time course of angiotensin II levels suggested that the lack of a cumulative effect from additive doses of intravenous enalapril was a reflection of complete inhibition of converting enzyme. One patient did not respond to enalapril; despite comparable hemodynamic severity of CHF, the renin-angiotensin system was not activated in this patient. Thus, intravenous enalapril is capable of rapid and complete inhibition of converting enzyme for the accurate assessment of angiotensin II--mediated vasoconstriction in patients with severe CHF.

Elementary steps in the reaction mechanism of chicken liver fatty acid synthase. pH dependence of NADPH binding and isotope rate effect for beta-ketoacyl reductase

The stopped flow method has been used to determine the pH dependence of the kinetics of the binding of NADPH to chicken liver fatty acid synthase over the pH range 6.0-8.5. The kinetics is consistent with a one-step binding mechanism, and the pH dependence of the second order rate constant indicates that an ionizable group either on the enzyme or on NADPH with a pK alpha of 6.1 is of importance in the binding process. The isotope rate effects have been determined for the steady state reaction with (S)- and (R)-[4-2H] NADPH as substrates and are very small. The pH dependence of the rate constant characterizing the reduction of acetoacetyl by NADPH on the enzyme (beta-ketoacyl reductase) and the isotope rate effects on this constant with (S)-[4-2H]NADPH as substrate also have been measured with the stopped flow method. A small pH-dependent isotope rate effect is found; these results suggest hydride transfer is not rate limiting for the beta-ketoacyl reductase reaction on the enzyme surface. The pH dependence of this rate constant is bell shaped and is very similar to that of the turnover number for the overall reaction; this suggests that the beta-ketoacyl reductase reaction may be partially rate limiting for the overall reaction when the enzyme is saturated with substrates.