An L-Form of Staphylococcus aureus Adapted to a Brain Heart Infusion Medium without Osmotic Stabilizers

An L-form derived from halotolerant Staphylococcus aureus Tasaki was adapted to growth in a brain heart infusion medium without any supplemental osmotically protective solutes (360 mOsm/kg). This L-form had no chemically detectable peptidoglycan residues on its surface. Electron microscopic observations confirmed morphologically the absence of the structures and also of other osmotically protective polymers within or exterior to the cytoplasmic membrane. The osmotic stability and susceptibility to bacitracin, d-cycloserine, and vancomycin of the L-form adapted to growth in 360 mOsm osmotically unprotective medium was higher than that of the L-form grown in 1,950 mOsm supplemented with 4.5% NaCl. The adapted L-form tended to be more sensitive to almost all of the antibiotics examined, other than the inhibitors for cell wall-synthesis, than the original L-form strain requiring osmotic protection for growth. Chemical analysis of the membrane of the adapted L-form indicated 16.3% total lipids and 20.6% proteins by dry weight of the membrane, and it contained larger amounts of lipid phosphorus (20.0 μ/mg).     

The Metabolic and Phagocytic Activities of Leukocytes from Patients Receiving Corticosteroid and Radiation Therapy,and Patients with Bacterial Infections

Peripheral blood leukocytes from patients given corticosteroid or radiation therapy, as well as patients with bacterial or viral infections, were studied with regard to the selected enzyme activities of the hexose monophosphate shunt (HMS). Glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD) and reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase were assayed spectrophotometrically on mixed leukocyte suspensions in isotonic glycerol. Enzyme activities of G-6-PD and NADPH oxidase in patients receiving corticosteroid or radiation therapy were significantly lower than the enzyme activity of 6-PGD. In patients with bacterial infections, activities of the three enzymes increased but in patients with viral infections, only the activities of NADPH oxidase and G-6-PD were slightly decreased. Nitroblue tetrazolium (NBT) dye-reducing activities of neutrophils from patients receiving corticosteroid or radiation therapy were attenuated which coincides with the reduced activities of HMS enzymes. From these results, it is likely that the reduced activities of intraleukocytic HMS enzymes of patients receiving corticosteroid or radiation therapy are correlated with intracellular bactericidal activities which might result from the attenuated level of hydrogen peroxide production.     

Intraleukocytic Bactericidal Activity in Patients Receiving Corticosteroid and Radiation Therapy,and in Patients with Diabetes Mellitus

Bactericidal activities of peripheral white blood cells obtained from patients and from healthy persons were examined in vitro. The results obtained are summarized as follows. 1. Peripheral white blood cells from patients receiving corticosteroid and radiation therapy showed decreased levels of intracellular bactericidal activities against Staphylococcus aureus. The leukocytes from almost all patients examined displayed intense activities of intracellular bacterial killing against Streptococcus pyogenes. 2. Only polymorphonuclear leukocytes (PMNs) and macrophages obtained from patients in severe stages of diabetes mellitus exhibited decreased levels of intracellular bactericidal activities against S. aureus. 3. The leukocytes from all patients examined exhibited the same levels of intracellular bactericidal effects against S. pyogenes as leukocytes from healthy persons. 4. Pseudomonas aeruginosa, which was phagocytized by PMNs obtained from healthy persons, demonstrated a remarkable degree of resistance to any intracellular bactericidal effect.     

Productivity of picoplankton compared with that of larger phytoplankton in the subarctic region

We determined the productivity (µg C µg^–1Chi a h^–1) of size-fractionated phytoplankton in the northernNorth Pacific and the Bering Sea in summer and winter. Picoplankton(<2 µm) were more productive than larger sized phytoplankton(2–10 and 10–200 µm) in the subtropical region,where the in situ temperature was >10°C; whereas picoplanktonin the subarctic region were similar in productivity or lessproductive than larger sized plankton, where the in situ temperaturewas <10°C. The result from the subtropical region inthis study agrees with previous results from tropical and subtropical waters, which indicate that phytoplankton productivitytends to decrease with increasing cell size. The result fromthe subarctic region, however, differs from previous results.We observed a positive linear regression for in situ temperatureand picoplankton productivity, but this trend was not seen inthe larger sized phytoplankton. The results show that the productivityof picoplankton is markedly influenced by in situ temperaturecompared with that of larger sized plankton. Low tem peratureappears to account largely for the observation that the productivityof picoplankton is not significantly higher than that of largersized phytoplankton in the subarctic region.     

Spectral densities of nitrogen nuclei in Escherichia coli ribonuclease HI obtained by 15N NMR relaxation and molecular dynamics

Summary Spectral densities of the ¹⁵N amide in Escherichia coli ribonuclease HI, obtained from NMR relaxation experiments, were compared with those calculated using a molecular dynamics (MD) simulation. All calculations and comparisons assumed that the auto-correlation function describing the internal motions of the molecule was independent of the auto-correlation function associated with overall rotational diffusion. Comparisons were limited to those residues for which the auto-correlation function of internal motions rapidly relaxed and reached a steady state within 205 ps. The results show the importance of frequency components as well as amplitudes of internal motions in order to obtain a meaningful comparison of MD simulations with NMR data.     

Changes in rhythmicity of ambulatory and drinking activities in immature female rats

Adult female rats showed increase in ambulatory activity and marked decrease in drinking behavior at early dark period (18:00-24:00) of proestrus stage before ovulation. In this study, we observed the changes in patterns of ambulatory and drinking activities of immature rats associated with estrous cycle during growing period. Immature female rats of the Wistar-Imamichi strain were used, and both behavioral activities were measured continuously, using Gundai type Ambulodrinkometer. From these observations, it was found that the typical patterns of ambulatory and drinking activities which were observed in adult female rats appeared at the sixth (51-60 days old) and the third (39-49 days old) estrous cycle, respectively.