Two types ofPropionibacterium avidum with different isomers of diaminopimelic acid

Of 38 strains ofPropionibacterium avidum, most fell into one of two groups. One group (20 strains) hadLl-diaminopimelic acid as the diaminoacid of peptidoglycan, did not ferment inositol, and reacted with serum to strain VPI 0576; the other group (11 strains) hadDl-diaminopimelic acid as the peptidoglycan diaminoacid, fermented inositol, and reacted with serum to strain VPI 0670. DNA sequence similarity studies showed that, while overall intergroup similarity was about 80%, within each group the sequence similarities were over 90%. Seven strains were anomalous and did not fit exactly into either group.The results show that the isomer of diaminopimelic acid in peptidoglycan may differ in strains of a single species all of which show at least 80% DNA sequence similarity to each other.     

8-Hydroxy-2'-deoxyguanosine formation during the catalytic oxidation of hydrazines in the presence of 2'-deoxyguanosine.

The reaction of 2'-deoxyguanosine (1), substituted hydrazines (Hy) and oxygen, in the presence of Cu(II) as catalyst, yields 8-hydroxy-2'-deoxyguanosine (2). The rate of formation of 2 was found to be dependent upon the oxidation potential of the Hy and on structural factors of the Hy. The conversion of 1 to 2 under these conditions suggested that a Haber-Weiss/Fenton type of process was involved with Hy acting as reductant. However, the dependence of the rate of the conversion of 1 to 2 upon the structure of Hy suggested that the Hy substrates studied may be more directly involved in the process than that of a reducing agent. Additional studies of this reaction system, including the oxygen consumption, radical trapping studies and direct ESR measurements suggest that the conversion of 1 to 2, under the conditions used, involves the intermediacy of complex composed of the metal catalyst, 1, Hy and oxygen. The rate data for the conversion of 1 to 2 appear to be correlated with the carcinogenicity of Hy and therefore 2 may be an important DNA adduct in the carcinogenesis of hydrazines.     

Size-selective grazing of bacteria by Bosmina longirostris--an image-analysis study

Image analyses on the filtering apparatus of Bosmina longirostricshowed that the filter mesh is finer on the gnathobasic filterplates of the second and third trunk limbs (ranges from 0.43to 0.97 µm) and coarser for the outer ones of the thirdlimb (ranges from 0.5 to 1.36 µm), and the intersetulardistances increase with body length. Grazing experiments combinedwith image analysis confirmed the efficient grazing of B.longirostrison natural bacteria with cell lengths equal to or larger thanthe intersetular distances of the gnathobasic filter plates.During the experiments, the animals minimized the average celllength of the bacterioplankton assemblages from 0.77–0.96µm to 0.55–0.68 µm, corresponding to the meanof the filter mesh size on the fine gnathobasic filter platesof the experimental populations. The clearance rates for large,elongated or dividing cells with maximal lengths of 0.88–8.40µm were 2.3–17.7 times higher than those for smallsingle coccoids with a diameter of <0.45 µm. The resultsprovide evidence of a significant differential impact of B.longirostrison the bacterial community structure with respect to the shapeand size of the cells, and demonstrate that the species is amore effective bacterial feeder than considered previously.     

Skeletal muscle contractile protein function is preserved in human heart failure

Skeletal muscle weakness is a common finding in patients with chronic heart failure (CHF). This functional deficit cannot be accounted for by muscle atrophy alone, suggesting that the syndrome of heart failure induces a myopathy in the skeletal musculature. To determine whether decrements in muscle performance are related to alterations in contractile protein function, biopsies were obtained from the vastus lateralis muscle of four CHF patients and four control patients. CHF patients exhibited reduced peak aerobic capacity and knee extensor muscle strength. Decrements in whole muscle strength persisted after statistical control for muscle size. Thin filaments and myosin were isolated from biopsies and mechanically assessed using the in vitro motility assay. Isolated skeletal muscle thin-filament function, however, did not differ between CHF patients and controls with respect to unloaded shortening velocity, calcium sensitivity, or maximal force. Similarly, no difference in maximal force or unloaded shortening velocity of isolated myosin was observed between CHF patients and controls. From these results, we conclude that skeletal contractile protein function is unaltered in CHF patients. Other factors, such as a decrease in total muscle myosin content, are likely contributors to the skeletal muscle strength deficit of heart failure.     

An evaluation of distress following intraperitoneal immunization with Freund's adjuvant in mice

Intraperitoneal immunization with Freund's adjuvant is frequently used to stimulate antibody production in mice. To evaluate the clinical and pathological effects of this technique, mice were immunized intraperitoneally with complete Freund's adjuvant and albumin, and the injection repeated 3-4 weeks later using incomplete Freund's adjuvant. This regimen induced a mean antibody titer against albumin of 1:280 within 7 days after booster immunization and increased the abdominal width, abdominal circumference and spleen weights of immunized animals. Food intake and body weight decreased after immunization, but returned to control levels within 1-2 weeks. Open-field activity was not affected. Neutrophilia, eosinophilia and monocytosis were present 7 days after immunization and persisted for the duration of the study. Gross and histopathological lesions included multiple granulomatous abdominal adhesions and lymphoid hyperplasia. Thus, intraperitoneal immunization with Freund's adjuvant and albumin produced some adverse effects in the animal (weight loss, neutrophilia and granulomatous peritonitis). However, the animals did not appear to be severely or chronically impaired, since food intake, body weight and locomotor activity were within normal limits for most of the post-immunization period.