Treatment with the glucagon receptor antagonist LY2409021 increases ambulatory blood pressure in patients with type 2 diabetes

AIMS

To assess the effect of LY2409021 on systolic blood pressure (SBP) in patients with type 2 diabetes.

MATERIALS AND METHODS

This 6-week, randomized, crossover study evaluated the effects of once-daily administration of LY2409021 20 mg vs those of placebo on SBP, diastolic BP (DBP), and mean arterial pressure (MAP) using 24-hour ambulatory BP monitoring (ABPM) in 270 subjects treated with diet/exercise ± metformin. Other measures included changes in glycemic control, serum lipids, and hepatic safety markers.

RESULTS

At 6 weeks of LY2409021 treatment, 24-hour mean SBP was increased, with a least squares mean (LSM) difference of 2.26 mm Hg vs placebo (95% CI: 1.11, 3.40; P  < .001). The 24-hour mean DBP and MAP also increased, with LSM differences of 1.37 mm Hg (95% CI: 0.66, 2.08; P  < .001) and 1.67 mm Hg (95% CI: 0.86, 2.47; P  < .001) vs placebo, respectively. At week 6, LY2409021 treatment reduced glycated hemoglobin (HbA1c) levels, with an LSM difference of -0.49% (-5.4 mmol/mol) (95% CI: -0.56%, -0.42% [-6.1, -4.6 mmol/mol]; P  < .001) vs placebo. Mean HbA1c at baseline was 7.3% (56 mmol/mol). Small but significant changes in serum lipid and aminotransferase levels were observed with LY2409021 treatment (all P  < .05 vs placebo).

CONCLUSIONS

Statistically significant increases in BP, MAP and serum lipid levels were observed with LY2409021 treatment at a dose that lowered HbA1c and glucose levels. These effects may limit the clinical utility of LY2409021 as a chronic treatment for type 2 diabetes.

Mobilising elementary and secondary school students for tuberculosis case finding in Anhui, China

OBJECTIVES

To evaluate the implementation of a FIDELIS (Fund for Innovative DOTS Expansion through Local Initiatives to Stop TB) project in Anhui Province, China.

DESIGN

A survey card was designed for students to identify individuals who might have tuberculosis (TB) in their family. Teachers provided health education on TB before distributing the survey cards. Survey cards identifying individuals with respiratory symptoms for ≥3 weeks were sent by the teachers to village doctors who were trained to visit symptomatic individuals and advise them to undergo sputum examination. Data were routinely collected in the implementation of the FIDELIS project, and quarterly reports from the National Tuberculosis Programme were analysed. The detection of new smear-positive TB cases before and after FIDELIS, as well as with and without FIDELIS, were compared.

RESULTS

In the first year, a total of 2 387 405 students were involved and 23 079 symptomatic individuals were examined, among whom 2307 (10.3%) were diagnosed with smear-positive TB. Case detection in FIDELIS counties increased by a factor of 3.5 during the FIDELIS period compared with before FIDELIS, and that in non-FIDELIS counties by a factor of 3.1 (P = 0.001).

CONCLUSION

It was feasible to massively mobilise students for TB case finding through collaboration between the health care and education systems.

Gene polymorphisms associated with susceptibility to coronary artery disease in Han Chinese people

This study investigated 5 single nucleotide polymorphism (SNP) haplotypes in susceptibility genes for coronary artery disease (CAD) and the putative involvement of these SNPs in CAD in the Chi-nese Han population. From March 2008 to June 2009, we selected 119 CAD patients and 115 subjects not related to the CAD of Chinese Han or-igin as controls. The SNP genotypes were performed by multiplex SNaP-shot technology. The HNRPUL1 gene rs11881940T and GATA2 gene rs3803T loci were highly correlated with CAD (P < 0.05). rs10757278G increased the risk of CAD in patients indicated by an odds ratio (OR) = 1.242 [95% confidence interval (CI) = 1.04-1.49]; rs11881940T and rs3803T were protective factors for CAD with ORs = 0.767 (95%CI = 0.61-0.97) and 0.53 (95%CI = 0.40-0.72), respectively. Analysis of the rs10757278, rs11881940 and rs3803 loci showed that haplotypes ATC (OR = 4.26; 95%CI = 2.85-6.40, P < 0.01), GAC (OR = 1.50; 95%CI = 1.25-1.81, P < 0.01) and GAT (OR = 1.53; 95%CI = 1.12-2.09, P < 0.01) were CAD risk factors, whereas GTC was protective (OR = 0.48; 95%CI = 0.32-0.72, P < 0.01). ATC and glucose were positively correlated (OR = 1.91; 95%CI = 1.01-3.61, P < 0.05). GAT was a risk factor for hyper-tension (OR = 2.86; 95%CI = 1.40-5.83, P < 0.01). In conclusion, poly-morphisms and haplotype analysis of susceptibility genes for CAD can improve predicting this disease and will enable early diagnosis of CAD.

[HOE642 (Cariporide) reduces the intracellular calcium overload of isolated immature rabbit ventricular myocytes induced by anoxia/reoxygenation]

AIM

To observe the effects of HOE642 (Cariporide) on intracellular free calcium in isolated immature rabbit ventricular myocytes induced by anoxia/reoxygenation, and to search the protective mechanism of the Na+/H+ exchange inhibitor on immature rabbit hearts.

METHODS

The ventricular cardiomyocytes isolated from six New Zealand immature rabbit hearts were divided into three groups of each heart, which were attained by mean of collagenase (type II, 0.28 mg/ml) perfusion. All cells were incubated with calcium fluorescence indicator Fluo-3/AM, and then the intracellular free calcium was measured under the laser scanning confocal microscopy. As well as the creatine phosphokinase (CK) and lactic dehydrogenase (LDH) were measured. The baseline was measured after isolation without anoxia/reoxygenation. The control group received anoxic conditions for 60 minutes and reoxygenation for 30 minutes, then measured. The experiment group received the same conditions as control group with addition of HOE642 (1 micromol/L).

RESULTS

After anoxia/reoxygenation, the intracellular free calcium of isolated immature rabbit ventricular myocytes and CK, LDH in control group increased significantly than baseline (P < 0.01), there were no significant difference of immature myocardial [Ca+]i and CK, LDH between experiment group and baseline (P > 0.05), and the experiment group myocardial [Ca2+]i and CK, LDH reduced significantly than control (P < 0.01).

CONCLUSION

HOE642 (Cariporide) may reduce intracellular calcium overload and the enzymes level (CK, LDH) in isolated immature rabbit ventricular myocytes induced by anoxia/reoxygenation, so the protective mechanism of HOE642 on immature rabbit heart may be by inhibition of the intracellular free calcium overload.

Fathering and children's sex role orientation in Korea

The purpose of this exploratory study was to examine variation in aspects of contemporary Korean fathering, such as warmth and involvement (frequency and task share), and its relationship to children's sex role development. One hundred and twenty-nine Korean families (fathers, mothers, and their 11- to 13-year-old children) completed standardized questionnaires addressing child-rearing practices, parental involvement, spousal support, and sex role orientations. Statistical analyses of the data revealed that warmth of fathering and father involvement (frequency and task share) were not significantly associated with children's sex role orientations. However, girls' femininity was significantly related to fathers' masculinity.

Establishment of a biological indicator for the radiation and safety of diagnostic ultrasound using apoptosis

We have studied, by a nonisotopic in situ end-labeling (ISEL) technique, the frequency of apoptosis in the intestinal crypt cell of adult mice and in the external granular layer(EGL) of the cerebellum of fetuses by gamma-ray irradiation from 60Co or diagnostic ultrasound exposure. The extent of changes following 200 cGy(1090 cGy/min) was studied at 2, 4, 6, 8, 12, or 24 hours after exposure. The maximal frequency was found 4-8 hours after exposure. The mice that received 18, 36, 54, 108, 198, 396 cGy of gamma-rays or diagnostic ultrasound (7.5 MHz, 4.2 mW, ISPTA = 7.9 mW/cm2, IsppA = 114.3 W/cm2) for 10 or 30 minutes were examined 6 hours after irradiation. Measurements performed after gamma-ray irradiation showed a dose-related increase in apoptotic cells in each of the mice studied. The dose-response curves were analyzed with alpha linear-quadratic model: the frequency (number per crypt) of apoptotic cells in the intestinal crypt of adult mice was y = (0.0386 +/- 0.004204)D + (-0.0000535 +/- 0.00001120)D2 + 0.15475(r2 = 0.952, y = apoptotic cell per crypt cell, D = dose in cGy), and the frequency (percentage of apoptotic cell in the EGL) of apoptotic cell in the EGL of fetus was y = (0.1349 +/- 1.175)D + (-0.001522 +/- 0.334)D2 + 0.0477(r2 = 0.981, y = % of apoptotic cell in the EGL, D = dose in cGy). In the experiment of ultrasound exposure, the frequencies of apoptosis were 0.181 +/- 0.055(10 minutes exposure) and 0.325 +/- 0.294 (30 minutes exposure) in the crypt cells and 0.106 +/- 0.130% (10 minutes exposure) and 0.167 +/- 0.220%(30 minutes exposure) in the EGL. We estimated the relative dose of the yield from the experiment with ultrasound by substituting the yield from ultrasound exposure into the curue from the gamma-irradiation. The relative doses of ultrasound exposure compared with gamma-irradiation were 0.692 cGy(10 minutes exposure) and 1.334 cGy(30 minutes exposure) in the experiment for crypt cells and 0.432 cGy(10 minutes exposure) and 0.885 cGy(30 minutes exposure) in the experiment for EGL. Although there is presently no evidence to indicate that diagnostic ultrasound involves a significant risk, it is not wise to use diagnostic ultrasound indiscriminately.

Radioprotective effects of two traditional Chinese medicine prescriptions: si-wu-tang and si-jun-zi-tang

We performed this study to determine the effect of Si-Wu-Tang, a basic prescription of traditional Oriental medicine as a blood-building decoction (Chinese medical concept: Bu-Xie), Si-Jun-Zi-Tang, a basic prescription as an energy tonic (Chinese medical concept: Bu-Qi) and its major ingredients on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of gamma-irradiation. Si-Wu-Tang administration before irradiation protected the jejunal crypts (p < 0.0005), increased the formation of endogenous spleen colonies (p < 0.05) and reduced the frequency of radiation-induced apoptosis (p < 0.05). In an experiment on the effect of ingredients of Si-Wu-Tang, the result indicated that extract of Danggui and Baishaoyao might have a major radioprotective effect. The radioprotective effect of Si-Jun-Zi-Tang and its ingredients were not as significant as that of Si-Wu-Tang. Although the mechanisms of this inhibitory effect remain to be elucidated, these results indicate that Si-Wu-Tang might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the protective nature of Si-Wu-Tang extract and its ingredients.

Effects of green tea catechin on phospholipase A2 activity and antithrombus in streptozotocin diabetic rats

The purpose of this study was to investigate the effects of dietary green tea catechin on phospholipase A2 (PLA2) activity and the antithrombotic reaction of platelets in streptozotocin (STZ)-diabetic rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly divided into one normal and three STZ-diabetic groups, which were subdivided into catechin-free group (DM-0C), 0.5% catechin group (DM-0.5C) and 1% catechin group (DM-1C). The activity level of platelet phospholipase A2 was higher in the diabetic groups than in the normal group, while it was lower in DM-0.5C and DM-1C than in DM-0C. The activity of platelet cyclooxygenase in DM-0C was 1.1-fold as high as in the normal group, but was significantly reduced by catechin supplementation. The platelet thromboxane A2 (TXA2) formation became higher in DM-0C as compared to the normal group, but not in DM-0.5C and DM-1C. The synthesis of aortic prostacyclin (PGI2) was lower in DM-0C and DM-0.5C than in the normal group. The PGI2/TXA2 ratio was decreased to 55% in DM-0C, but was restored by catechin supplementation. These results indicate that STZ-diabetic rats are sensitive to platelet aggregation and thrombosis, and that the abnormality can be improved by dietary catechin.

Depolarizing cardiac arrest and endothelium-derived hyperpolarizing factor-mediated hyperpolarization and relaxation in coronary arteries: the effect and mechanism

OBJECTIVES

Depolarizing (hyperkalemic) solutions are widely used to preserve organs for transplantation and for cardiac operations. We previously observed that exposure to hyperkalemia reduced endothelium-dependent, noncyclooxygenase- and non-nitric oxide-mediated relaxation. This study was designed to examine the mechanism of this effect with regard to K channels and the associated membrane potential changes.

METHODS

Porcine coronary artery rings were studied in organ chambers. After incubation of the tissue with 20 or 50 mmol/L doses of potassium for 1 hour, the endothelium-derived hyperpolarizing factor-mediated relaxation in the artery and the membrane hyperpolarization in a single coronary smooth muscle cell were studied.

RESULTS

The endothelium-derived hyperpolarizing factor-mediated relaxation induced by substance P, which could be significantly inhibited by the Ca(2+)-activated K channel blocker tetraethylammonium but only to a lesser extent by the adenosine triphosphate-sensitive K channel blocker glibenclamide, was significantly reduced. Substance P-induced hyperpolarization of the membrane potential was also significantly reduced by the hyperkalemic incubation with a significantly elevated resting membrane potential.

CONCLUSIONS

Depolarizing arrest reduces endothelium-derived hyperpolarizing factor-mediated membrane hyperpolarization and relaxation by affecting mainly the Ca(2+)-activated K channels and by depolarizing the membrane for a prolonged period. We suggest that this is one of the mechanisms for coronary dysfunction after exposure to depolarizing (hyperkalemic) cardioplegic and organ-preservation solutions and that, therefore, "perfect" protection of the heart or other organs should restore the endothelium-derived hyperpolarizing factor-related endothelial function.

Surgical preparation abolishes endothelium-derived hyperpolarizing factor-mediated hyperpolarization in the human saphenous vein

BACKGROUND

The impairment of the synthesis and release of endothelium-derived relaxing factors may be related to the high incidence of atherosclerosis and occlusion in saphenous vein grafts. This study focused on the effect of surgical preparation on one of the endothelium-derived relaxing factors, endothelium-derived hyperpolarizing factor, in the human saphenous vein.

METHODS

Human saphenous vein segments taken from patients undergoing coronary bypass were placed in an organ bath. A glass microelectrode was inserted into a smooth muscle cell. The membrane potential in response to acetylcholine (-9 to -5 log M) was measured in normal or surgically prepared saphenous vein with presence or absence of NG-nitro-L-arginine (300 mumol/L) and indomethacin (7 mumol/L).

RESULTS

The resting membrane potential was -71.28 +/- 1.91 mV (n = 7) with intact endothelium and -65.5 +/- 2.92 mV (n = 6, p > 0.05) without endothelium. Acetylcholine hyperpolarized membrane potential with intact endothelium (-90.57 +/- 1.48 mV, n = 7, p < 0.001), but not without endothelium (-69.67 +/- 2.93 mV, n = 6, p > 0.05). In the surgically prepared saphenous vein, acetylcholine did not hyperpolarize membrane potential (-71.83 +/- 3.84 mV versus the resting membrane potential of -69.50 +/- 3.53 mV, n = 6, p > 0.05).

CONCLUSIONS

The endothelium-derived hyperpolarizing factor plays a role in the human saphenous vein. The surgical preparation abolishes the endothelium-derived hyperpolarizing factor-mediated hyperpolarization in the saphenous vein. This study provides evidence of functional changes of endothelium by traditional surgical preparation from another point of view, and it may be related to the high incidence of occlusion in saphenous vein grafts.

Hyperkalemia alters EDHF-mediated hyperpolarization and relaxation in coronary arteries

Hyperkalemic solutions are widely used to preserve organs for transplantation and for cardiac surgery. The present study was designed to test the hypothesis that hyperkalemia may alter endothelial function through a non-nitric oxide (NO) pathway, since preliminary studies have shown that the NO pathway may not be affected. Porcine coronary artery rings were studied in organ chambers. After incubation with 20 or 50 mM K+ for 1 h, the indomethacin- and NG-nitro-L-arginine+ (L-NNA)-resistant relaxation induced by A23187 or bradykinin, which could be further inhibited by tetraethylammonium but not glibenclamide, was significantly reduced. Incubation with hyperkalemia also significantly increased the concentration eliciting 50% of the maximal response to A23187 and bradykinin. A23187-induced hyperpolarization of the membrane potential was significantly reduced by hyperkalemic incubation. However, 1-h incubation with hyperkalemia does not affect the endothelial Ca2+ concentration. We conclude that exposure to hyperkalemia reduces the indomethacin- and L-NNA-resistant endothelium-dependent relaxation and endothelium-dependent hyperpolarization. This reduction in the relaxation and hyperpolarization is related to the endothelium-derived hyperpolarizing factor by affecting its effect on the smooth muscle cell, probably through partially depolarizing the membrane, and the Ca2(+)- activated K+ channels rather than by affecting its biosynthesis and/or release in the endothelial cell. Our study may suggest a new mechanism for coronary dysfunction after exposure to hyperkalemic cardioplegia and organ preservation solutions.

A study of autobiographical memories in depressed and nondepressed elderly individuals

An autobiographical memory task was used to study memory processes and depression in elderly individuals. Twenty-seven nondepressed and twenty-seven depressed elderly participants recalled thirty memories. Each memory was self-rated for happiness versus sadness and the degree of importance of the event at the time the event occurred (i.e., "then") and looking back on the event ("now"). Nondepressed participants perceived greater positive change in affective tone between "then" and "now" ratings. Depressed participants recalled more memories rated as sad "now" than nondepressed, and perceived negative and positive memories to become more neutral than nondepressed participants. These results are consistent with a mood congruence hypothesis, in that participants recalled more memories affectively consistent with current mood, and a self-enhancement view of reminiscing, such that recalling memories evaluated as happier was associated with less depression.

Structural characteristics of cyclodextrins in the solid state

A comparison of alpha-, beta-, and gamma-cyclodextrins in the solid state is made. Monomeric features analyzed include orientations of primary hydroxyl groups and pyran ring pucker. Macromolecular features examined include planarity of the oligomer, tilting of pyran rings, and, deviation from Cn symmetry where n = number of monomers. The mean values and standard deviations of these shape descriptors are given for cyclodextrins with and without guests embedded in their interiors. Molecular mechanics calculations using the MM2, AMBER, and CHARMM force fields show that most solid state cyclodextrins are trapped in high-energy conformations relative to the most stable forms found in this study.

Effect of luminance on suprathreshold contrast perception

Perceived contrast was measured under natural viewing conditions with the use of contrast-matching and magnitude-estimation paradigms and found to be independent of luminance over a range of luminances from 37.5 down to 8 cd/m2. However, this contrast constancy broke down when the dimmer target was below 8 cd/m2. The perceived contrast of the dimmer target then fell below that expected from contrast constancy. The extended range of contrast constancy previously reported [J. Physiol. 252, 627 (1975); Vision Res. 16, 1419 (1976)] has been thought to imply neural mechanisms with unlimited constancy, but these researchers permitted differential adaptation to the brighter and dimmer targets, which were seen haploscopically (by different eyes). As our natural-viewing procedure ensured that both bright and dim targets were presented to retinal areas in a roughly constant state of adaptation, our failure to find extended contrast constancy implies an important limitation on the neural processing of contrast.

IL-2 gene inducibility in T cells before T cell receptor expression. Changes in signaling pathways and gene expression requirements during intrathymic maturation

The ability to express the growth hormone IL-2 upon stimulation gives T lymphocytes one of their major effector functions in the immune system. IL-2 is apparently synthesized only by T cells, and only by a subset of T cells which constitutes a "helper" class. It remains unknown how and when the IL-2-producing lineage becomes distinct from other functional effector lineages. We have therefore examined immature T cell precursors to determine when IL-2 inducibility is acquired in relation to other maturation events, such as expression of an Ag-binding TCR, which is suspected to play an influential role in the determination of subclass commitment. In mature T cells, IL-2 is inducible via agonists of the phosphoinositide pathway, a network of signaling mediators shared by a wide variety of metazoan cell types. The universality of this activation pathway makes it seem less likely, a priori, to be a target of developmental change than the intrinsic susceptibility to induction of the IL-2 locus. However, our results presented here refute this expectation. In this report, we show that both TCR+ cells and pre-T cells too immature to express TCR can be induced to express IL-2 at high levels. The induction requirements for IL-2 expression, however, are different in TCR- and TCR+ cells. Even by using Ca2+ ionophore and phorbol ester to bypass the requirement for the TCR in cell activation, the TCR- cells also require the presence of the polypeptide hormone IL-1. By contrast, TCR+ mature cells not only can express IL-2 without IL-1, but also show no response to IL-1 when Ca2+ ionophore and phorbol ester are present. IL-1-dependent IL-2 producers appear in the thymus of repopulating radiation chimeras before "mature" (TCR+) T cells, whereas IL-1-independent IL-2 production is found only afterward. Thus, IL-2 inducibility per se apparently precedes TCR expression and all TCR-associated fate determination events. However, developmental alteration of signal transduction pathways may play a vital regulatory role in the later allocation of particular functional responses to appropriate lineages of T cells.

IL-2 gene inducibility in T cells before T cell receptor expression. Changes in signaling pathways and gene expression requirements during intrathymic maturation

The ability to express the growth hormone IL-2 upon stimulation gives T lymphocytes one of their major effector functions in the immune system. IL-2 is apparently synthesized only by T cells, and only by a subset of T cells which constitutes a "helper" class. It remains unknown how and when the IL-2-producing lineage becomes distinct from other functional effector lineages. We have therefore examined immature T cell precursors to determine when IL-2 inducibility is acquired in relation to other maturation events, such as expression of an Ag-binding TCR, which is suspected to play an influential role in the determination of subclass commitment. In mature T cells, IL-2 is inducible via agonists of the phosphoinositide pathway, a network of signaling mediators shared by a wide variety of metazoan cell types. The universality of this activation pathway makes it seem less likely, a priori, to be a target of developmental change than the intrinsic susceptibility to induction of the IL-2 locus. However, our results presented here refute this expectation. In this report, we show that both TCR+ cells and pre-T cells too immature to express TCR can be induced to express IL-2 at high levels. The induction requirements for IL-2 expression, however, are different in TCR- and TCR+ cells. Even by using Ca2+ ionophore and phorbol ester to bypass the requirement for the TCR in cell activation, the TCR- cells also require the presence of the polypeptide hormone IL-1. By contrast, TCR+ mature cells not only can express IL-2 without IL-1, but also show no response to IL-1 when Ca2+ ionophore and phorbol ester are present. IL-1-dependent IL-2 producers appear in the thymus of repopulating radiation chimeras before "mature" (TCR+) T cells, whereas IL-1-independent IL-2 production is found only afterward. Thus, IL-2 inducibility per se apparently precedes TCR expression and all TCR-associated fate determination events. However, developmental alteration of signal transduction pathways may play a vital regulatory role in the later allocation of particular functional responses to appropriate lineages of T cells.

Influence of activating stimulus on functional phenotype: interleukin 2 mRNA accumulation differentially induced by ionophore and receptor ligands in subsets of murine T cells

We have investigated the linkage between CD4/CD8 phenotype and programming for specific responses in primary T-cell populations. In situ hybridization has been used to determine the frequency of cells competent to express the interleukin 2 (IL-2) gene after short-term stimulation with various polyclonal activators. The effects of the T-cell receptor ligands Con A and anti-CD3 monoclonal antibody were compared with those of a calcium ionophore that bypasses membrane receptors altogether. Induction with a calcium ionophore and phorbol ester revealed that potential IL-2 producers not only constitute greater than 85% of the cells with a CD4+ "helper/inducer" phenotype but also constitute over half of the cells with a CD8+ "killer/suppressor" phenotype. There is no defect in the ability of these CD8+ cells to accumulate IL-2 transcripts under these conditions. By contrast, in response to phorbol ester and either Con A or anti-CD3, the CD8+ cells show an abortive IL-2 production response with rapid disappearance of IL-2 mRNA. This results in substantially lower yields of IL-2 per cell than is made by CD4+ cells in response to the same stimuli. The extent to which these populations appear to have diverged in function thus depends on the stimulus used to trigger the response. The results suggest that differences in signal transduction or posttranscriptional regulatory mechanisms, rather than effector gene inducibility per se, may initially underlie the commitment of CD4+ and CD8+ cells to distinct functional roles.

The nucleotide sequence of a major glutamine tRNA from rat liver

A major glutamine tRNA from rat liver was purified. Post-labeling techniques showed its nucleotide sequence to be: pG-G-U-U-C-C-A-U-m(1)G-G-U-G-psi-A-A-D-Gm-G-D-D-A-G-C-A-C-U-C-U-G-G-A-Cm-U-C-U-G-A-A-psi-C-C-A-G-C-G-A-U-m(5)C-m(5)C-G-A-G-psi-psi-C-A-m(1)A-A-U-C-U-C-G-G-U-G-G-A-A-C-C-U-C-C-A(OH).Images

The nucleotide sequence of a glutamate tRNA from rat liver

A glutamate tRNA from rat liver was purified. By means of post-labeling techniques, its nucleotide sequence was shown to be: pU-C-C-C-A-C-A-U-m1G-G-U-C-psi-A-G-C- G-G-D-D-A-G-G-A-U-U-C-C-U-G-G-psi-U-mcm5s2U-U-C-A-C-C-C-A-G-G-C-G- G-C-m5C-m5C-G-G-G-Tm-psi-C-G-A-C-U-C-C-C-G-G-U-G-U-G-G-G-A-A-C-C-AOH. The sequence is remarkably similar to that of tRNA4Glu from Drosophila melanogaster. Only 10 out of 75 nucleotides in the two tRNAs are different.

The nucleotide sequence of a glutamine tRNA from rat liver

A glutamate tRNA from rat liver was purified. By means of post-labeling techniques, its nucleotide sequence was shown to be: pU-C-C-C-A-C-A-U-m1G-G-U-C-psi-A-G-C- G-G-D-D-A-G-G-A-U-U-C-C-U-G-G-psi-U-mcm5S2U-U-C-A-C-C-C-A-G-G-C-G- G-C-m5C-m5C-G-G-G-Tm-psi-C-G-A-C-U-C-C-C-G-G-U-G-U-G-G-G-A-A-C-C-AOH. The sequence is remarkably similar to that of tRNAGlu from Drosophila melanogaster. Only 10 out of 75 nucleotides in the two tRNAs are different.

Inhibition of DNA synthesis in cultured lymphocytes and tumor cells by extracts of betel nut, tobacco, and miang leaf, plant substances associated with cancer of the ororespiratory epithelium

The high incidence of oropharyngeal, esophageal, and laryngeal cancers in certain parts of the world has been ascribed to conjugated tannins found in certain folk medicinal herbs. We extracted miang leaf and betel nut with phosphate-buffered saline (0.14 M NaCl, 0.15 M potassium phosphate buffer, pH 7.4) and found that the extracts inhibited [3H]thymidine incorporation by phytohemagglutinin-stimulated human lymphocytes and by rat mammary tumor and mouse L-cells in logarithmic growth. Pretreating the lymphocytes for 1 or 4 hr with the extracts inhibited phytohemagglutinin-induced thymidine incorporation 72 hr later. At concentrations of 2.5 volumes % or lower, miang and betel nut extracts inhibited thymidine incorporation by 40 to 98% without any apparent signs of toxicity as demonstrated by the 66Rb equilibrium assay. In addition, neither extract inhibited cytotoxicity of rat mammary tumor cells by immune syngeneic spleen cells. The molecular weights of the inhibitory factors were between 1,000 and 10,000 daltons as determined by ultrafiltration and were unaffected by boiling for 3 min or by treatment with alcohol and, therefore, are probably not proteins. This in vitro demonstration of inhibition of DNA synthesis by these plant extracts presumably enriched for conjugated tannins may relate to inhibition of growth of rats and chicks fed conjugated tanin-contaminated sorghum feed. The carcinogenic potential of either these extracts or conjugated tannins is not yet established.