AMP deaminase, 5'-nucleotidase and adenosine deaminase in rat myocardial tissue in myocardial infarction and hypothermia

AMP deaminase, 5'-nucleotidase and adenosine deaminase have been estimated in skeletal muscle and myocardial tissue in normal rats and in rats subjected to experimental myocardial infarction or hypothermia. A difference in the enzyme distribution was found between the right and left ventricles in the normal rat. A decrease in the activity of 5'-nucleotidase and an increase in the activity of adenosine deaminase were observed in infarcted myocardial tissue. The activity of all 3 enzymes was found to be depressed in the myocardium in rats subjected to hypothermia. These results are discussed in relation to adenosine production and its beneficial effects.     

Changes in activity levels of AMP deaminase and adenosine deaminase in the Indian apple snail,Pila globosa (Swainson) during starvation and aestivation stress

Summary Activity levels of AMP deaminase and adenosine deaminase have been studied in hepatopancreas, foot and mantle tissues ofPila globosa with reference to starvation and aestivation. The activity levels of both enzymes were decreased in all the tissues of aestivating snails while in starved animals AMP deaminase activity was increased, in contrast to the decreased adenosine deaminase activity.Acknowledgments. K. Srinivasa Moorthy and B. Kasi Reddy are thankful to the Department of Science and Technology, New Delhi for the financial assistance. Reprint requests should be addressed to C.S.C.     

AMP deaminase, 5′-nucleotidase and adenosine deaminase in rat myocardial tissue in myocardial infarction and hypothermia

Summary AMP deaminase, 5-nucleotidase and adenosine deaminase have been estimated in skeletal muscle and myocardial tissue in normal rats and in rats subjected to experimental myocardial infarction or hypothermia. A difference in the enzyme distribution was found between the right and left ventricles in the normal rat. A decrease in the activity of 5-nucleotidase and an increase in the activity of adenosine deaminase were observed in infarcted myocardial tissue. The activity of all 3 enzymes was found to be depressed in the myocardium in rats subjected to hypothermia. These results are discussed in relation to adenosine production and its beneficial effects.     

Nuclear protrusions in malignant tumours with large abnormal chromosomes: Observations on C-banded preparations

Summary The appearances are described in 4 human tumours having nuclear protrusions associated with large abnormal chromosomes. In C-banded preparations, chromocentres were seen in the protrusions only where interstitial C-bands were present on the long arm of the abnormal chromosome, providing evidence that the protrusions are indeed formed by the long arms.This work was supported by a grant from the Cancer Research Campaign.     

Alpha-tocopherol: Its inhibition on human platelet aggregation

Summary Alpha-tocopherol inhibits human platelet aggregation induced by arachidonate sodium, collagen, epinephrine, adenosine diphosphate or thrombin — arachidonate sodium being the most susceptible. The second phase of the biphasic platelet aggregation induced by epinephrine or adenosine diphosphate is preferentially inhibited.This work was supported by the Medical Research Council of Canada, Quebec Medical Council, and a Fraser Scholarship, McGill University. I thank Drs.K. N. Drummond andS. O'Regan for their comments.     

Nuclear protrusions in malignant tumours with large abnormal chromosomes: observations on C-banded preparations.

The appearances are described in 4 human tumours having nuclear protrusions associated with large abnormal chromosomes. In C-banded preparations, chromocentres were seen in the protrusions only where interstitial C-bands were present on the long arm of the abnormal chromosome, providing evidence that the protrusions are indeed formed by the long arms.     

Human adenosine deaminases ADA1 and ADA2 bind to different subsets of immune cells

At sites of inflammation and tumor growth, the local concentration of extracellular adenosine rapidly increases and plays a role in controlling the immune responses of nearby cells. Adenosine deaminases ADA1 and ADA2 (ADAs) decrease the level of adenosine by converting it to inosine, which serves as a negative feedback mechanism. Mutations in the genes encoding ADAs lead to impaired immune function, which suggests a crucial role for ADAs in immune system regulation. It is not clear why humans and other mammals possess two enzymes with adenosine deaminase activity. Here, we found that ADA2 binds to neutrophils, monocytes, NK cells and B cells that do not express CD26, a receptor for ADA1. Moreover, the analysis of CD4+ T-cell subset revealed that ADA2 specifically binds to regulatory T cells expressing CD39 and lacking the receptor for ADA1. Also, it was found that ADA1 binds to CD16? monocytes, while CD16+ monocytes preferably bind ADA2. A study of the blood samples from ADA2-deficient patients showed a dramatic reduction in the number of lymphocyte subsets and an increased concentration of TNF-α in plasma. Our results suggest the existence of a new mechanism, where the activation and survival of immune cells is regulated through the activities of ADA2 or ADA1 anchored to the cell surface.     

Cytogenetic studies of Hynobiidae (Urodela). IX. Karyological characteristics ofHynobius abei Sato by means of R-and C-banding

Summary Chromosomal characteristics of the salamander speciesHynobius abei, from Ohimya (Kyoto) were revealed by the techniques of R-and C-banding. The karyotype ofH. abei was characterized by the shortness of an R-negative (C-positive) band in the terminal region of the long arm of chromosome 2 and a band encompassing the whole short arm of chromosome 10. These two bands inH. abei were the shortest among those of the variousHynobius species that have been examined. Otherwise no differences could be detected betweenH. abei and seven other pond-type species ofHynobius (2n=56) in terms of the banding patterns of 18 specifically identifiable pairs of their chromosomes.     

The nucleolar chromosome in embryos of Rana pipiens

Summary Karyotype analyses of prometaphases from medullary plate cells derived from mid-neurulae of Rana pipiens have led to the identification of the nucleolar chromosome and nucleolar organizing region, which is located on the longer arm of a small sub-metacentric chromosome (No. 10).Supported in part by research grant GB19631X from the Natioal Science Foundation. This study constituted a portion of a dissertation submitted by G. R. N. to the Medical College of Pennsylvania in partial fulfillment of requirements for a Ph. D. degree.Supported by NDEA and subsequently NSF predoctoral traineeships.To whom reprint requests should be sent.     

A transmission and scanning electron microscopic study of cytoplasmic threads of dividing neuroepithelial cells in early chick embryos

Summary Cytoplasmic threads found on the luminal surface of the developing chick neuroepithelium contain a remnant of the spindle complex and an electron-dense midbody. Most threads become long and thin and eventually split at the midbody. This finding suggests that the midbody plays a role in the final separation of daughter cells.This study was supported in part by grants from the Research Council and the Charles and Johanna Busch Memorial Fund of Rutgers University.     

Distribution of sister chromatid exchanges in different types of chromatin in the X chromosome ofMicrotus cabrerae

We used the X chromosomes ofMicrotus cabrerae as a model to analyze the distribution of sister chromatid exchanges (SCEs) on different types of chromatin, because of the marked heterogeneity of the heterochromatin in the entire short arm and a portion of the long arm of this chromosome. Computer-simulated distributions, according to an algorithm that makes it possible to modify the distribution on the basis of any possible hypothesis, were compared with real distributions by log-linear models. We found that the frequency of SCEs in different types of heterochromatin was higher than that expected for a random distribution, and located an SCE hot-spot at the junction between euchromatin and heterochromatin. The possible relationship between the distribution of SCEs and base composition or chromatin accessibility are discussed.     

Normaler und aberranter Karyotyp vonCepaea hortensis (Müller) (Gastropoda)

Summary The karyotype of 9Cepaea hortensis were analyzed. The haploid chromosome number was 22. 2 types of longest chromosomes were encountered. In 8 out of 9 animals, the longest chromosome had an arm ratio of 1.2. One animal showed a ratio of 4.9. This aberration is thought to have arisen by a pericentric inversion. Because both the normal and the aberrant chromosome coexisted in the same population, a chromosomal polymorphism seems to be present.     

Constitutive heterochromatin and nucleolus organizer region in the knifefish,Apteronotus albifrons (Pisces,Apteronotidae)

Summary The C-banding and silver staining of the chromosomes of the knifefishApteronotus albifrons (2n=24), demonstrated the presence of constitutive heterochromatin in the centromeric region of every chromosome, except pair 4, where the entire long arm was darkly stained, the silver stain positive nucleolus organizer region (NOR) being embedded in it.The authors are grateful to Dr Sen Pathak (University of Texas System Cancer Center at Houston, Texas, USA) and Dr Yatiyo Yassuda (Universidade de São Paulo, São Paulo, Brasil) for their suggestions. This study was supported in part by grants of the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq).     

Examination of naturally occurring polyacetylenes and α-terthienyl for their ability to induce cytogenetic damage

Summary -Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither -terthienyl nor phenylheptatriyne induced chromosome aberrations.The authors wish to thank the National Science and Engineering Research Council for financial support of this research.     

Induction of uncoiled chromosomes by vibration

Summary Chromatin condensation during metaphase can be removed by simple vibration of metaphase cells prior to fixation. Uncoiled chromosome arms consist of long threads with dense regions at irregular distances each from the other.Acknowledgment. This work is supported by the Hellenic Anticancer Institute.     

Contradictory differential staining results with Coomassie Brilliant Blue and silver carbonate on sister chromatids

Summary Coomassie Brilliant Blue, and silver stain, are used in electrophoretic gels to identify polypeptides. The relative staining intensity has been taken as indicating a quantitative difference between proteins. However, when these 2 stains were applied to 2 identically pretreated chromosome preparations, contradictory staining results were obtained.Acknowledgment. This work is supported under the auspices of the National Science Council, Republic of China.     

Research Articles¶Naturally occurring 2′-O-methylpurine nucleosides with hypotensive properties

2′-O-Methylinosine (1) has been isolated for the first time and shown to be an intrinsic hypotensive principle. Its probable in vivo precursor, 2′-O-methyladenosine (3), showed stronger and even orally potent hypotensive activity. Resistance of the methyladenosine (3) against adenosine deaminase is thought to contribute to its long-lasting activity. The effect of both nucleosides (1 and 3) was not accompanied with any significant change in heart rate, which is often observed with adenosine. Received 2 October 1997; accepted 28 October 1997     

Intercellular bridges of chick blastoderm studied by scanning and transmission electron microscopy

Summary Chick blastoderms were studied by scanning and transmission electron microscopy to identify by both methods a type of thread-like structure lying on the epiblast. The structure was identified by transmission microscopy as a long telophase bridge containing mid-body and spindle remnant. It apperas to provide cytoplasmic continuity between only 2 cells.Supported by a grant from The Medical Research Council of Canada.     

Karyotypic races of the common shrew (Sorex araneus L.) from northern Poland

Karyotypic races of the common shrew which differed with respect to the combinations of chromosome arms in certain 2-armed autosomes were distinguished in Poland. Two eastern races with the arm combination ik, and one western race with the arm combination hi in the third pair of autosomes were established. In the contact area of these chromosomal forms, the fourth karyotypic race with the arm combination hk was found.     

Karyotypic races of the common shrew (Sorex araneus L.) from northern Poland

Summary Karyotypic races of the common shrew which differed with respect to the combinations of chromosome arms in certain 2-armed autosomes were distinguished in Poland. Two eastern races with the arm combinationik, and one western race with the arm combinationhi in the third pair of autosomes were established. In the contact area of these chromosomal forms, the fourth karyotypic race with the arm combinationhk was found.I wish to express my gratitude to my wife, A.M. Wójcik, M. Sc., for her help in catching the animals and making chromosome preparations. I must also offer my thanks to Dr J. Zima for giving me access to his as yet unpublished data, and to Prof. Z. Pucek and Dr S. Fedyk for reading the first draft of this paper.