Adduct formation of pyrroloquinoline quinone and amino acid

When pyrroloquinoline quinone (PQQ) is mixed with an amino acid, a corresponding Schiff base PQQ adduct is readily formed between carbonyl groups of PQQ and the primary amino group. A potent growth stimulating effect for microorganisms was observed with the PQQ adduct when it was administered in a culture medium. Although PQQ itself shows a marked growth stimulating effect, PQQ adducts appeared to be more active than authentic PQQ when compared on a molar basis. Conversely, unlike authentic PQQ, PQQ adducts were shown to be less active (greater than or equal to 100-fold) as the prosthetic group for a quinoprotein apo-glucose dehydrogenase when examined by holoenzyme formation by exogenous addition of PQQ or PQQ adducts. These observations suggested that PQQ adduct formation readily occurs during isolation procedures for PQQ from biological materials or PQQ - chromophore from quinoproteins. Therefore, the presence of such adducts gives a PQQ estimation much lower than theoretically expected. As an example, formation, isolation and characterization of PQQ - serine are described.     

Alteration of hepatic lipidperoxide levels during cataract formation caused by glucocorticoids in developing chick embryos

The level of hepatic lipidperoxides in chick embryos was determined during cataract formation resulting from glucocorticoid treatment. When 15 day old chick embryos were administered 0.25 mumol of hydrocortisone acetate their hepatic lipidperoxide level, determined by thio-barbituric acid, increased after a lag time of 20 hr and reached approximately 8-fold of control at 48 hr after the treatment. These studies indicate that the peroxidation of lipid in tissues should be considered in elucidating mechanisms of action or adverse effects of glucocorticoids.     

The effects of retinoic acid on heart formation in the early chick embryo.

The vitamin A derivative retinoic acid has previously been shown to have teratogenic effects on heart development in mammalian embryos. The craniomedial migration of the precardiac mesoderm during the early stages of heart formation is thought to depend on a gradient of extracellular fibronectin associated with the underlying endoderm. Here, the effects of retinoic acid on migration of the precardiac mesoderm have been investigated in the early chick embryo. When applied to the whole embryo in culture, the retinoid inhibits the craniomedial migration of the precardiac mesoderm resulting in a heart tube that is stunted cranially, while normal or enlarged caudally. Similarly, a local application of retinoic acid to the heart-forming area disrupts the formation of the cardiogenic crescent and the subsequent development of a single mid-line heart tube. This effect is analogous to removing a segment of endoderm and mesoderm across the heart-forming area and results in various degrees of cardia bifida. At higher concentrations of retinoic acid and earlier developmental stages, two completely separate hearts are produced, while at lower concentrations and later stages there are partial bifurcations. The controls, in which the identical operation is carried out except that dimethyl sulphoxide (DMSO) is used instead of the retinoid, are almost all normal. We propose that one of the teratogenic effects of retinoic acid on the heart is to disrupt the interaction between precardiac cells and the extracellular matrix thus inhibiting their directed migration on the endodermal substratum.     

吡咯喹啉醌生理医学功效研究进展

吡咯喹啉醌(PQQ)是一种小分子醌类化合物,由某些细菌合成作为细菌脱氢酶氧化还原反应的辅助因子,并广泛存在于各种生物组织中。综述了其在生理医学功效方面的研究进展情况,分析其在神经退行性疾病、心脏病、解毒、消炎、抗癌、预防白内障及骨代谢疾病等方面的临床应用潜力,并对其未来在水生生物生理生态学领域的研究方向进行了展望。     

Physical properties, lipid composition and enzyme activities of hepatic subcellular membranes from chick embryo after ethanol treatment.

Exposure of chick embryos to ethanol resulted in significant alterations to the lipid composition of various different hepatic subcellular membranes. A marked decrease in cholesterol levels and an increase in the phospholipid content of microsomes and mitochondria was observed. Ethanol also affected the fatty acid profiles, mainly by decreasing the percentage of oleic acid in phosphatidylcholine and phosphatidylethanolamine in the mitochondria and phosphatidylethanolamine in the microsomes. In spite of these changes ethanol only induced alterations in the fluidity of the mitochondrial membranes, which showed a more rigid core, in contrast to the phospholipid-head region, which was not affected. In accordance with the changes observed in the physical state of the membrane, the enzymes involved in the microsomal electron-transport systems were not modified by ethanol, while cytochrome oxidase activity decreased by 50% compared to the activity in the mitochondria from control chick embryos. These findings establish that during the chick-embryo developmental period the mitochondria are more sensitive to ethanol than are the microsomes.     

Lethal and teratogenic effects of long-term low-intensity radio frequency radiation at 428 MHz on developing chick embryo

Exposure of developing chick embryos to 428 MHz radio frequency (RF) radiation at a power density of 5.5 mW/cm2 for more than 20 days resulted in embryolethal and/or teratogenic effects and delayed hatching. These adverse biological effects were not due to any thermal effect of the RF radiation. We have demonstrated teratogenicity in the chick embryo as a result of protracted low-dose RF irradiation.     

Development of chick embryo conjunctival papillae and scleral ossicles after hydrocortisone treatment

The effects of hydrocortisone injection on the development of conjunctival papillae and scleral ossicles were studied in New Hampshire Red chick embryos.Hydrocortisone injected at several different incubation stages reduced the number of conjunctival papillae and the eventual number of scleral ossicles which were produced. Repeated injections given at selected stages caused characteristic patterns of papilla deficiency.The ability to manipulate this system predictably may prove useful in the study of cell activity and supercellular organization during the initiation of organ formation.     

Vitamin A economy of the developing chick embryo and of the freshly hatched chick

1. The changes in the net amounts of retinol, retinyl esters and retinal in both the developing chick embryo and the newly hatched chick were investigated. The embryo requires about 68nmol of the vitamin for its growth, whereas the baby chick requires about 108nmol during the first 7 days after hatching. 2. Retinal was present in the egg in fairly high concentrations at the beginning of the incubation but it virtually disappeared from the extra-embryonic tissue after day 17 of incubation. It was not found in the liver of the embryo or of the newly hatched chick up until day 7.     

Hydrolase and serum treatment of normal chick embryo cells: effects on hexose transport.

We have asked whether treatment of normal cultured cells with proteases, other hydrolytic enzymes, or serum can convert them into transient phenocopies of transformed cells with respect to the very high rate of hexose transport characteristic of transformed cells. Treatment of density-inhibited cultures of normal chick embryo fibroblasts with trypsin, plasmin, neuraminidase, or hyaluronidase stimulated their rate of 2-deoxyglucose uptake to a level only marginally higher than that seen in normal exponentially growing cultures, and only 35-45% of that seen in transformed cultures. Addition of the hydrolytic enzymes to growing cell cultures had little effect on 2-deoxyglucose uptake. Serum, however, could stimulate 2-deoxyglucose uptake all the way up to the transformed level. Even though the hydrolases and serum differed in their ability to stimulate 2-deoxyglucose uptake, both reagents were capable of stimulating cell division equally well. Evidence is presented suggesting that the hexose transport rate is controlled by serum factors, and that proteolysis can affect the response of the cells of these factors.     

Alpha-fetoprotein expression in intra- and extraembryonic fluids of developing chick embryo

The ontogeny of alpha-fetoprotein (AFP) has been studied in the chicken (from 7 days of incubation until 2 days after hatching) using (1) the two-dimensional immunoelectrophoresis technique, (2) the polyacrylamide gel electrophoresis, and (3) the high resolution two-dimensional polyacrylamide gel electrophoresis. The molecular weight of AFP was estimated at 71,000. AFP was seen as a heterogeneous population composed of four isoforms which slightly differ by their isoelectric points. Up to the 18th day of development, qualitative changes in AFP heterogeneity do not occur. Only traces of the two alkaline isoforms were observed in plasma of 2 days post-hatching chickens. AFP has been identified in allantoic and cerebrospinal fluids but is not present in amniotic fluid. At 7 days of embryonic age, all the plasma AFP species are present in cerebrospinal fluid.     

Cadmium and lead toxicity effects on zinc, copper, nickel and iron distribution in the developing chick embryo

The teratologic effects on chicken embryos induced by the load of 100 micrograms of cadmium or lead nitrate salts injected into the yolk on day 5 of incubation as well as their effects upon zinc, copper, nickel and iron distribution were studied. Despite a significant teratologic influence of lead, cadmium administration did not induce significant effects. A week after injections, embryo lead content, but not cadmium concentration, increased; this differential action suggested an active uptake of lead by the embryo, not observed for cadmium. Both cadmium and lead affected significantly the iron, copper and zinc homeostasis in the egg. Cadmium induced these changes probably through alterations in the metallic ion transport processes towards the embryo.     

Hybrid formation of rabbit and rat hepatic glutathione S-transferases

1. A reconstitution experiment resulted in the formation of new proteins between limited combinations of rat and rabbit hepatic glutathione S-transferases: AA(subunit composition: YcYc) and R3b(Y3Y3), Lig(YaYa) and R3b(Y3Y3), and A(Yb1Yb1) and R2(Y2Y2). 2. It was demonstrated that the new protein formed between R2 and A had the subunit composition of Y2Yb1, suggesting a hybrid of rabbit (R2) and rat isozyme (A). 3. This hybrid protein showed intermediate spec. acts between those of R2 and A when either 1-chloro-2,4-dinitrobenzene (CDNB) or 1,2-dichloro-4-nitrobenzene (DCNB) was employed as the substrate.     

Elevation of blood lipid peroxide (TBA-reacting substance) level in developing chick embryos after glucocorticoid administration

When 15-day-old chick embryos were administered 0.25 mumol of hydrocortisone hemisuccinate sodium (HC) the lipid peroxides (LPO) level increased after a lag time and reached about 9-fold of control level at 48 h after the treatment. Thereafter, the amount of LPO decreased to near control level by 72 h. Data obtained by using various steroids indicated that the marked elevation of LPO in blood was related to glucocorticoid effects caused by a high dose administration. The elevation of LPO level in blood was prevented by triple administration of ascorbic acid (20 mumol/egg) at 3, 10 and 20 h after HC treatment.     

Hyaluronidase activity and hyaluronate content of the developing chick embryo heart.

Hyaluronidase activity and hyaluronate content were measured in the developing chick heart from embryonic day 3 through posthatching stages. High levels of both enzyme and substrate were found during the earliest stages examined. Hyaluronidase activity gradually declined to 63% of the initial (day 3) level by embryonic day 16. Enzyme activity decreased more sharply during the next 4 days to 30% of the initial level and remained constant through 2 weeks after hatching. Low levels of enzyme activity (about 10% initial levels) were still detectable in 10-week-old chicken hearts. The heart hyaluronidase is an endoglycosidase with an estimated molecular weight of 62,000, which degrades hyaluronate and, to a lesser extent, chondroitin sulfate at an acid pH optimum. Hyaluronate constituted approximately 50% of the total glycosaminoglycan content at embryonic day 5. Between embryonic days 5 and 12, the concentration of hyaluronate decreased to 25–30% of the initial level and remained constant thereafter. The level of other glycosaminoglycans decreased more gradually than hyaluronate and did not reach a constant level until hatching. This pattern of hyaluronidase activity and hyaluronate concentration presumably reflects the extensive tissue remodeling which transforms the developing heart from a thin-walled tube containing extensive regions of extracellular matrix to a compact, thick-walled myocardium having a limited extracellular compartment.     

Fate of egg white trypsin inhibitor and start of proteolysis in developing chick embryo and newly hatched chick

Trypsin inhibitor and proteolytic activities were studied in incubated eggs, embryos, and newly hatched chicks. After rupture of the secondary seroamniotic suture at 11 days, the trypsin inhibitor content of the albumen gradually passes into the amniotic cavity; from there it is taken up orally by the chick embryo. It is supposed that between 11 and 18 days of embryonic development the trypsin inhibitor passes from the gut to the yolk sac through the vitellointestinal duct. The thin yolk contained only traces of trypsin inhibitor, and the allantoic fluid was entirely free from it. The amylase activity demonstrable in the liquid intestinal contents of the chick embryo indicates the presence of pancreatic secretion. The trypsin inhibitor probably suppresses the proteases not only directly, but also through prevention of the activation of zymogens. Enterocytes of chick embryos showed no morphological indication of the absorption of undigested proteins on histological examination. The cloacal membrane of the newly hatched chick ruptures shortly after the bird has dried up, and the trypsin inhibitor is subsequently eliminated along with the intestinal contents. The intestinal proteolytic enzymes appear immediately afterward. The proteolytic activity appeared regardless of whether the birds were or were not fed. Maximum proteolytic activity was measured in the small intestine of chicks that were fasted for 2 days after hatching. The pattern of proteolytic enzymes as well as their sensitivity to protease inhibitors did not notably differ from that of mammals.