Development of the Cardiac Conducting System in the Chick Embryo

Chick embryos at 3 to 15 days of incubation were examined for the developmet and differentiation of the "four rings" of the heart. It was clarified that nodes and bundles of the impulse conducting system in the adult chicken were derived from these rings. This finding was very important for understanding the cardiac conducting system in birds and mammals.     

Development of a PCR test for the identification of Staphylococcus intermedius based on the 16S rDNA sequence

The development of a PCR assay based on the 16S ribosomal RNA gene (rDNA) sequence was carried out for the identification of Staphylococcus intermedius. Sixty-six strains of S. intermedius, 70 of Staphylococcus aureus and 2 of Staphylococcus hyicus were examined for the assay. The 16S rDNA, of which the PCR target fragment makes up 901 bp corresponding to the sequence data of the gene, was detected in all strains of S. intermedius, but it was not detected in any strains of either S. aureus or S. hyicus. These results suggest that the PCR allows a simple and precise identification of S. intermedius.     

Effects of epidermal growth factor (EGF) on fetal islet B cells in vitro

ABSTRACT. It has been reported that when the rat fetus is treated with streptozotocin (STZ) in vivo, islet B cells are destroyed but later recover. To investigate the process of the recovery of B cells after in vitro treatment of the fetal pancreas with STZ and the role of epidermal growth factor (EGF) in the recovery of B cells, we measured the level of insulin released from the cultured fetal pancreas and examined it histologically. As a result, we immunohistologically confirmed the regeneration of B cells in the pancreas that had been cultured for 48 hr after destruction of islet B cells by STZ treatment. An immunohistologic study using proliferating cell nuclear antigen (PCNA) showed that without the addition of EGF, the cell division index was significantly higher in the STZ-treated group (STZ group) than in the untreated group (intact group), whereas with the addition of EGF, the cell division index increased in both groups, but EGF did not have a significant cell division-promoting effect on the pancreas in the STZ group. The addition of EGF caused a significant decrease in the concentration of insulin in culture medium in both groups. These results indicate that EGF has a cell growth-promoting effect on intact fetal pancreas in vitro but has the effect of inhibiting the release of insulin, and thus suggest that EGF does not trigger the regeneration of islet B cells.     

Serum activities of tartrate-resistant acid phosphatase and bone specific alkaline phosphatase as indices of bone metabolism in the cow

The correlation between the serum hydroxyproline concentration and serum activity levels of TRAP and BALP was examined in 41 cows. The correlated coefficient (r) was 0.6391 for TRAP and 0.3147 for BALP, respectively. Judging from the significant correlation to the serum hydroxyproline concentration, serum TRAP activity is an index for bone metabolism in cows. Serum TRAP activity was therefore measured in 205 healthy cows (2-9 years old) in order to observe the changes in bone resorption with aging and milk production. TRAP levels differed slightly between group A (< or =4 yrs) and B (5 yrs< or =) at the same stage of lactation. The activity levels rose slightly at the height of lactation stage and during the dry stage.     

Distribution of mecA-harboring staphylococci in healthy mares

The prevalence of staphylococci that harbor the mecA gene responsible for methicillin resistance was examined in healthy breeding mares. Staphylococci often cause diseases of horses such as metritis, keratitis, and abscess. Methicillin-resistant staphylococci would make antibiotic treatments ineffective, so it may be significant to know the distribution of mecA-harboring staphylococci in mares. Isolation of mecA-harboring staphylococci was achieved from nares and pasterns of 100 mares in Hokkaido, Japan. From 13% of the mares, mecA-harboring staphylococci, including 15 isolates of Staphylococcus sciuri and 3 of Staphylococcus lentus, were isolated. Isolates of S. sciuri were found to be genetically polyclonal by pulsed-field gel electrophoresis. These isolates produced no PCase and showed low or no resistance to beta-lactam and other classes of antibiotics. Distribution of staphylococcal species and levels of antibiotic resistance were found to be different between isolates from the present mares and those previously reported from riding-horses. Antibiotic pressure may lead to these differences. In addition, it appears that mecA-harboring S. sciuri may be native to horses.     

Lactate dehydrogenase and creatine phosphokinase isoenzymes in tissues of laboratory animals

The lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) isoenzyme distributions in tissues of the ICR mouse, Wistar rat, guinea pig and golden hamster were analyzed by histoelectrophoresis. Tissues obtained were as follows: liver, pancreas, stomach, small intestine, heart, femoral muscle, uterus, kidney, spleen, lymph node, cerebrum, spinal cord and erythrocyte. Histoelectrophoresis was for the direct analysis of LDH and CPK isoenzymes in the tissues and had high practical value compared with previous tissue-extraction methods. In tissues of the mouse, guinea pig and golden hamster, LDH isoenzymes showed five bands. In the rat, LDH isoenzyme was separated into four fractions. CPK isoenzyme showed three bands; BB, MB and MM. In some tissues, the MM band was separated into two sub fractions.     

Chemical modification of wood by non-formaldehyde cross-linking reagents

Summary Using sulfur dioxide (SO₂) as catalyst, wood specimens were treated with nonformaldehyde cross-linking reagents such as glyoxal, glutaraldehyde and dimethylol dihydroxy ethyleneurea (DMDHEU). The results of dimensional stability, acoustic properties, and mechanical strength tests were compared with those obtained from formaldehyde treatment. With glyoxal and glutaraldehyde treatments, antiswelling efficiency (ASE) reached around 70%, which is comparable to the values attained by formaldehyde treatment, although the accompanying weight gain was much larger than for the latter, whereas DMDHEU did not give sufficiently high ASE. None of the treatments, significantly increased specific dynamic Young's modulus (E/) with the exception of the DMDHEU treatment, loss tangent (tan ) decreased substantially, about 50 and 60% in longitudinal and radial directions respectively, which were somewhat exceeding the formaldehyde treatment. The results suggested that the improvement of the dimensional stability and acoustic properties is partly attributed to the formation of cross-links.     

Formation and chemical structures of acid-soluble lignin I: sulfuric acid treatment time and acid-soluble lignin content of hardwood

To elucidate the formation mechanism of acidsoluble lignin (ASL) formed in the Klason lignin determination, beech wood meals were treated with sulfuric acid (SA) under various conditions, and the ASL solution was extracted with CHC1₃. The results indicated the following: (1) wood components yielding ASL are dissolved in 72% SA during the initial stage; (2) the quantity of ASL is highest during the initial stage, then decreases with prolonged time of 72% SA treatment and finally reaches a constant value; (3) soluble lignin prepared by 72% SA treatment and subsequent standing in 3% SA again yield insoluble Klason lignin and ASL after boiling in 3% SA; and (4) about half the amount of ASL is dissolved in CHC1₃. The foregoing suggest that wood components yielding ASL are dissolved in 72% SA at the beginning and finally change to ASL after being subjected to depolymerization, hydrolysis, and other reactions. ASL may thus be composed of low-molecular-weight degradation products and hydrophilic derivatives of lignin.     

Analysis of the structure of lignin-carbohydrate complexes by the specific13C tracer method

In the present study the specifically¹³C-enriched lignin precursors of biosynthesis (i.e., coniferin-[side chain–¹³C], coniferin-[side chain-–¹³C] and coniferin-[side chain-–¹³C]) were synthesized and administered exogeneously to ginkgo shoots (Ginkgo biloba L.) to obtain¹³C-enriched lignin-carbohydrate complexes (LCCs). The specifically¹³C-enriched LCCs were isolated from the newly formed xylem of ginkgo shoots administered with the¹³C-enriched precursors and degraded by enzymes. Lignin-rich fractions, so called enzyme-degraded LCCs (EDLCCs), were obtained. By determining their¹³C-NMR spectra, information related to the chemical structure of lignin building units and linkages between phenylpropane units of lignin and carbohydrates were obtained. It was found that these precursors were incorporated in natural lignin successfully. Three lignin-carbohydrates linkages (i.e., ether type, ester type, ketal type) were found at the C -position of the side chain of phenylpropane units in ginkgo LCC. No lignin-carbohydrate bond at the C- or C-position of the lignin side chain was observed in the¹³C-NMR spectra of the¹³C-enriched LCCs. This fact indicates that a specific¹³C tracer technique can be useful in NMR study of the chemical structure of LCCs.Part of this paper was presented at the 5th Pacific Polymer Conference, Kyongju, Korea, October 1997