Protective effect of puerarin against myocardial reperfusion injury. Myocardial metabolism and ultrastructure

To ascertain the beneficial effect of puerarin on the myocardium against reperfusion injury, studies on myocardial metabolism and ultrastructure were made. Twelve dogs divided into two equal groups were placed on moderate hypothermic cardiopulmonary bypass, and their hearts were subjected to 140 minutes cold cardioplegic arrest and 60 minute reperfusion. In the control group, the hearts were perfused with crystalloid cardioplegic solution (CPS) every 20 minutes during arrest. In the treated group, the hearts received CPS containing puerarin (2 mg/kg). Myocardial oxygen consumption, lactate production, creatine phosphokinase (CPK) release, water content and ultrastructural alterations were determined before ischemia, during cardiac arrest and at reperfusion. The results showed that intermittent infusion of CPS containing puerarin significantly decreased myocardial lactate production during ischemia, as well as myocardial oxygen consumption, CPK release and water content during reperfusion. Under electronmicroscopy, the degree of ischemic damage judged by a scoring method was less pronounced in the puerarin group than in the control. The authors conclude that puerarin has protective effects on the function of hearts that have undergone long periods of arrest and reperfusion.

The protective effect of puerarin against myocardial reperfusion injury. Study on cardiac function

In order to find out if puerarin could protect the hearts from myocardial reperfusion injury after cardiac arrest, twelve dogs divided into two equal groups were placed on moderately hypothermic cardiopulmonary bypass and their hearts were subjected to 140 min of cold cardioplegic arrest and 60 min of reperfusion. In the control group, the hearts were perfused with a crystalloid cardioplegic solution (CPS) through the aortic root every 20 min during arrest. In the treated group, the hearts received CPS containing puerarin (2 mg/kg). Cardiac hemodynamic variables were monitored throughout the experiments. Left ventricular function curves were formed before ischemia and after 60 min of reperfusion. The results showed that the recovery of left ventricular function in the treated group was significantly better than that in the controls (81 +/- 11% versus 39 +/- 7%, P less than 0.01). Compared with preischemic values, the increase of coronary blood flow (CBF) at cardiac arrest in the puerarin-treated group was higher than that in the control group (214 +/- 11 versus 177 +/- 4 ml/min, P less than 0.01). The data indicate that puerarin has protective effects on the cardiac function after prolonged arrest and reperfusion.

Translocations and rearrangements in T-cell acute leukemias with the t(11;14) (p13;q11) chromosomal translocations

Chromosomal translocations involving the T-cell receptor alpha and delta genes at q11 on chromosome 14 are the most common cytogenetic abnormalities in patients with T-cell tumors. We have demonstrated that the t(11;14)(p13;q11) translocation in two T-ALL patients involves the J delta region suggesting that the translocation proceeds or coincides with delta gene rearrangement. Additional rearrangements on both normal and translocated chromosomes 14 are described including rearrangement of both Tcr-alpha and Tcr-delta genes, and deletions within the J alpha region. The polyclonality of rearrangements on the normal chromosome 14 in one of the patient samples demonstrates that T-cell receptor rearrangement continues after the translocation event. The identification of clonally expanded rearrangements involving both the Tcr-delta and the Tcr-alpha genes in a single patient suggests a cascade model for delta----alpha expression may be a viable pathway for T-cell maturation.

Interactions between glucocorticoid receptor-bearing chromatin and antireceptor antibody preparations

Recent evidence indicates that the control of gene expression by steroid hormones is mediated by hormone-receptor complexes bound at specific chromosomal locations. The isolation of these in vivo sites of binding would be useful in an analysis of the mechanism of this control. We have therefore examined the interaction between two different antiglucocorticoid receptor antibody preparations and a defined chromatin fraction containing bound glucocorticoid receptors in order to test the feasibility of this approach. Both antibody preparations, when attached to sepharose, removed nucleosome-bound and nucleosome free receptor from solution, indicating that chromatin-bound receptor was exposed and available for reaction with antibody. The bulk of the chromatin, not containing receptor, was mainly unaffected during these reactions, showing that the antibodies exhibited significant specificity. To determine whether the nucleosome-bound receptor remained attached to the nucleosome during reaction with antibody, studies using soluble antibody were performed. One of the antibodies caused a shift in the sedimentation rate of the nucleosome-bound receptor from 11S to 11.5S, suggesting that an intact ternary complex of antibody-receptor-nucleosome had formed. The other antibody produced various-sized aggregates of the free and bound receptors. Surprisingly, we found that one of the antibodies reacted strongly with free and nucleosome-bound estrogen receptors as well as glucocorticoid receptors. These studies suggest that an antibody preparation with appropriate characteristics should permit isolation of chromosomal receptor binding sites.

The induction of Alu-sequence transcripts by glucocorticoid in rat liver cells

Two cDNA clones isolated from a library prepared from dexamethasone-treated rat hepatoma cells have permitted us to detect the presence and the induction of heterogeneous, mainly short, RNA molecules in hepatoma cells and in rat liver, but not in several other rat tissues. The induction by dexamethasone is inhibited by 100 X progesterone. Pulse label experiments suggest that it occurs in part at least, at the level of transcription and may be mediated by RNA polymerase III. The induction of the RNAs is stimulated by cycloheximide, even in the absence of hormone, but not significantly by other stressful conditions. One line of hepatoma cells spontaneously lost its ability to induce these RNAs and synthesized them constitutively. These altered cells showed proper induction of another dexamethasone-mediated response, indicating that the glucocorticoid receptor was functionally normal in these cells. The two clones contain a type 2 Alu-like sequence. The short RNAs can be distinguished from 7SL RNA, which also contains Alu-sequences. We hypothesize that the synthesis of these RNAs may be regulated by an inhibitor of transcription which is inactivated by dexamethasone. Accordingly, cycloheximide relieves the inhibition by preventing synthesis of the inhibitor and the altered cell line has spontaneously lost the function of the inhibitor. The function of these RNAs for the cell is not known. We believe this to be the first report of hormone-regulated tissue specific synthesis of repeat-sequence transcripts.

Cloning and sequencing of a rearranged V lambda gene from a Burkitt's lymphoma cell line expressing kappa light chains

We have cloned and sequenced a rearranged V lambda gene from a Burkitt's lymphoma cell line PA682(PB). This cell line has two rearranged kappa loci and has been shown to be expressing kappa light chains. This V lambda gene has been identified as a member of the V lambda subgroup III gene family based on the homology of the predicted amino acid sequence of PAV lambda with the reported sequences of the V lambda protein DEL of subgroup III. Nine cross-hybridizing bands have been detected on Southern blots and the chromosomal orientation of the V lambda subgroup III gene family has been determined in relation to the V lambda subgroup I gene family. Although the PAV lambda rearrangement has occurred via a legitimate V-J joining and a normal size transcript is detected on Northern blots, the nucleotide sequence reveals a high level of mutations resulting in multiple termination signals within the V gene coding sequence and only a truncated V lambda protein can be translated. This confirms previous observations that although multiple light chain genes may be transcribed, only one functional light chain protein can be synthesized.

Identification of glucocorticoid-induced genes in rat hepatoma cells by isolation of cloned cDNA sequences

The expression of specific cellular genes in M1.19 rat hepatoma cells involves glucocorticoid regulation by mechanisms that are not well understood. To approach this problem we cloned cDNA prepared from dexamethasone-induced poly(A)-RNA and used a comparative colony hybridization method to identify recombinant clones containing hormone-regulated sequences. Two such cDNA clones, p1394 and p255, hybridize to a homogeneous RNA species of 900 nucleotides that is present in high abundance in 24-hr-induced cells but is undetectable in uninduced cells. This RNA can be seen as early as 1 hr after dexamethasone stimulation. Inhibition of protein synthesis with cycloheximide significantly reduces the accumulation of the RNA but does not abolish the induction response. In normal adult rat liver the RNA is abundant, and this RNA is induced by dexamethasone in adrenalectomized rats. Plasmids p1394 and p255 contain sequences that are homologous to the mRNA coding for the acute-phase reactant protein alpha 1-acid glycoprotein. Two other cDNA clones, p655 and p333, hybridize to a more heterogeneous RNA species 200-400 nucleotides in size with a lower induction response to dexamethasone. Southern blot analysis of M1.19 genomic DNA indicates that p1394 and p255 are complementary to a single DNA fragment, whereas p655 and p333 are complementary to repetitive sequences in the M1.19 genome. It appears that the genetic domain of glucocorticoid control in M1.19 rat hepatoma cells involves low copy number genes such as alpha 1-acid glycoprotein as well as repetitive sequence elements.

Progesterone, glucocorticoid and estradiol receptors in MCF-7 cells bind to chromatin

MCF-7 cells contain progesterone, estradiol and glucocorticoid receptors. Following addition of these hormones to the growth medium of the cells, hormone-receptor complexes were found to sediment with chromatin fragments produced by trace digestion with micrococcal nuclease. The binding in all cases could be competed by excess unlabeled hormone. In each case the fragments with which the hormone-receptor complexes were associated tended to be smaller than the bulk chromatin fragments, indicating a greater sensitivity of those chromatin regions to the nuclease. The mononucleosomes released by more extensive digestion with micrococcal nuclease contained different amounts of each of the three hormone-receptor complexes. Progesterone could usually be detected on mononucleosomes only after very brief sedimentation analyses, whereas glucocorticoid- and estradiol-labeled mononucleosomes were stable during long centrifugations. Comparison of glucocorticoid- and estradiol-labeled mononucleosomes indicated that their sedimentation rates differed from one another and from bulk nucleosomes. Estradiol nucleosomes from MCF-7 cells and rat uterus (Senior and Frankel, 1978) sediment significantly faster than bulk nucleosomes, while glucocorticoid nucleosomes from MCF-7 cells and rat hepatoma cells sediment with, or even fractionally slower than, bulk nucleosomes.

Adaptive Changes in ATPase Activity in the Cells of Winter Wheat Seedlings during Cold Hardening

A cytochemical study of ATPase activity in the cells of cold hardened and nonhardened winter wheat (Triticum aestivum L. cv. Nongke No. 1) seedlings was carried out by electron microscopic observation of lead phosphate precipitation. ATPase activity associated with various cellular organelles was altered during cold hardening. (a) At 22 degrees C, high plasmalemma ATPase activity was observed in both cold hardened and nonhardened tissues; at 5 degrees C, high activity of plasmalemma ATPase was observed in hardened tissues, but not in unhardened tissues. (b) In nonhardened tissues, tonoplast and vacuoles did not exhibit high ATPase activity at either 22 or 5 degrees C, while in hardened tissues high activity was observed at both temperatures. (c) At 5 degrees C, ATPase activity of nucleoli and chromatin was decreased in hardened tissues, but not in nonhardened tissues. It is suggested that adaptive changes in ATPase activity associated with a particular cellular organelle or membrane may be associated with the development of frost resistance of winter wheat seedlings.