LeERF-1, a novel AP2/ERF family gene within the B3 subcluster, is down-regulated by light signals in Lithospermum erythrorhizon

We previously showed that ethylene might be involved in the process of shikonin biosynthesis regulated by light signals. Here, we cloned a full-length cDNA of LeERF-1, a putative ethylene response factor gene, from Lithospermum erythrorhizon using the RACE (rapid amplification of cDNA ends) method. Phylogenetic analysis revealed that LeERF-1 was classified in the B3 subfamily, together with ERF1 and ORA59 of Arabidopsis. Heterologous expression of LeERF-1 in Arabidopsis showed that LeERF-1:eGFP fusion protein was precisely localised to the nucleus, implying that it might function as a transcription factor. Detailed expression analysis with real-time PCR showed that LeERF-1 was significantly down-regulated by white, blue and red light, although the inhibitory effect of red light was relatively weak compared to other light conditions. Tissue-specific expression analysis also indicated that LeERF-1 was dominantly expressed in the roots, which grow in soil in darkness. These patterns are all consistent with the effects of different light signals on regulating formation of shikonin and its derivatives, indicating that LeERF-1 might be a crucial positive regulator, like other B3 subfamily proteins (such as ORCA3 and ORA59), in regulating biosynthesis of secondary metabolites.

Genetic variation in the beta, beta-carotene-9', 10'-dioxygenase gene and association with fat colour in bovine adipose tissue and milk

beta, beta-carotene-9', 10'-dioxygenase (BCO2) plays a role in cleaving beta-carotene eccentrically, and may be involved in the control of adipose and milk colour in cattle. The bovine BCO2 gene was sequenced as a potential candidate gene for a beef fat colour QTL on chromosome (BTA) 15. A single nucleotide base change located in exon 3 causes the substitution of a stop codon (encoded by the A allele) for tryptophan(80) (encoded by the G allele) (c. 240G>A, p.Trp80stop, referred to herein as SNP W80X). Association analysis showed significant differences in subcutaneous fat colour and beta-carotene concentration amongst cattle with different BCO2 genotypes. Animals with the BCO2 AA genotype had more yellow beef fat and a higher beta-carotene concentration in adipose tissues than those with the GA or GG genotype. QTL mapping analysis with the BCO2 SNP W80X fitted as a fixed effect confirmed that this SNP is likely to represent the quantitative trait nucleotide (QTN) for the fat colour-related traits on BTA 15. Moreover, animals with the AA genotype had yellower milk colour and a higher concentration of beta-carotene in the milk.

Increased adenosine monophosphate-activated protein kinase activity in rat hearts with pressure-overload hypertrophy

BACKGROUND

Recent reports suggest that activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), in response to acute changes in cellular energy status in cardiac and skeletal muscles, results in altered substrate utilization. We hypothesized that chronic alterations in myocardial energetics in hypertrophied hearts (left ventricular hypertrophy, LVH) will lead to elevated AMPK activity, which in turn regulates substrate utilization.

METHODS AND RESULTS

Using (31)P NMR spectroscopy and biochemical assays, we found that in LVH hearts, adenosine triphosphate (ATP) concentration decreased by 10%, phosphocreatine concentration decreased by 30%, and total creatine concentration was unchanged. Thus, the ratio of phosphocreatine/creatine decreased to one third of controls, and the ratio of AMP/ATP increased to 5 times above controls. These changes were associated with increased alpha(1) and alpha(2) AMPK activity (3.5- and 4.8-fold above controls, respectively). The increase in AMPK alpha(1) activity was accompanied by a 2-fold increase in alpha(1) expression, whereas alpha(2) expression was decreased by 30% in LVH. The basal rate of 2-deoxyglucose uptake increased by 3-fold in LVH, which was associated with an increased amount of glucose transporters present on the plasma membrane.

CONCLUSIONS

These results demonstrate for the first time that chronic changes in myocardial energetics in hypertrophied hearts are accompanied by significant elevations in AMPK activity and isoform-specific alterations in AMPK expression. It also raises the possibility that AMPK signaling plays an important role in regulating substrate utilization in hypertrophied hearts.

[A study comparing 131I versus 131I plus antithyroid drug in the management of Graves' disease]

OBJECTIVE

To ascertain whether the therapoutic effect of 131I is affected by the additional use of thyrostatic medication.

METHODS

One hundred and eighty-seven patients with Graves' disease (GD) were randomly assigned to treatment with 131I alone or plus thyrostatic medication(PTU) 3 days after the beginning of 131I therapy. All patients were examined every month for six months after treatment.

RESULTS

The cure of hyperthyroidism occurred in 71 of 93 patients(76.3%) treated with 131I alone and in 76 of 94 patients(80.5%) treated with 131I plus thyrostatic medication(PTU). There were no significant differences in cure rate between the two groups.

CONCLUSION

The additional use of thyrostatic medication 3 days after the beginning of 131I therapy will not affect the efficacy of 131I in the treatment of GD.

Endogenous nitric oxide enhances coupling between O2 consumption and ATP synthesis in guinea pig hearts

Endogenous nitric oxide (eNO) modulates tissue respiration. To test whether eNO modulates myocardial O2 consumption (MVO2), ATP synthesis, and metabolic efficiency, we used isolated isovolumic guinea pig hearts perfused at a constant flow. N(omega)-nitro-L-arginine (L-NNA; 5 x 10(-5) mol/l) was used to inhibit eNO production. MVO2 was measured at different levels of cardiac work, estimated as the rate-pressure product (RPP). ATP content and synthesis rate were determined using (31)P NMR and magnetization transfer during high cardiac work. L-NNA increased coronary vascular resistance (19 +/- 3%, P < 0.05) and MVO2 (12 +/- 3%, P < 0.05) without an increase in the RPP. In contrast, vehicle infusion resulted in insignificant changes in coronary vascular resistance (3 +/- 2%, P > 0.05) and MVO2 (-2 +/- 1%, P > 0.05). Compared with vehicle, L-NNA caused a higher MVO2 both during KCl arrest (L-NNA 5.6 +/- 0.5 vs. vehicle 3.0 +/- 0.4 micromol x min(-1) x mg x dry wt(-1), P < 0.05) and during increased cardiac work elicited by elevating perfusate Ca2+, indicating an upward shift in the relationship between contractile performance (measured as RPP) and MVO2. However, neither ATP contents nor ATP synthesis rates were different in the two groups during high cardiac work. Thus, because inhibition of eNO production by L-NNA increased MVO2 without a change in the ATP synthesis rate, these data suggest that eNO increases myocardial metabolic efficiency by reducing MVO2 in the heart.

Cardiac-specific expression of heme oxygenase-1 protects against ischemia and reperfusion injury in transgenic mice

Heme oxygenase (HO)-1 degrades the pro-oxidant heme and generates carbon monoxide and antioxidant bilirubin. We have previously shown that in response to hypoxia, HO-1-null mice develop infarcts in the right ventricle of their hearts and that their cardiomyocytes are damaged by oxidative stress. To test whether HO-1 protects against oxidative injury in the heart, we generated cardiac-specific transgenic mice overexpressing different levels of HO-1. By use of a Langendorff preparation, hearts from transgenic mice showed improved recovery of contractile performance during reperfusion after ischemia in an HO-1 dose-dependent manner. In vivo, myocardial ischemia and reperfusion experiments showed that infarct size was only 14.7% of the area at risk in transgenic mice compared with 56.5% in wild-type mice. Hearts from these transgenic animals had reduced inflammatory cell infiltration and oxidative damage. Our data demonstrate that overexpression of HO-1 in the cardiomyocyte protects against ischemia and reperfusion injury, thus improving the recovery of cardiac function.

Mutations that increase in situ priming also decrease circularization for duck hepatitis B virus

The process of hepadnavirus reverse transcription involves two template switches during the synthesis of plus-strand DNA. The first involves translocation of the plus-strand primer from its site of generation, the 3' end of minus-strand DNA, to the complementary sequence DR2, located near the 5' end of the minus-strand DNA. Plus strands initiated from DR2 are extended to the 5' end of the minus-strand DNA. At this point, the 3' end of the minus strand becomes the template via the second template switch, a process called circularization. Elongation of circularized plus-strand DNA generates relaxed circular DNA. Although most virions contain relaxed circular DNA, some contain duplex linear DNA. Duplex linear genomes are synthesized when the plus-strand primer is used at the site of its generation, the 3' end of the minus-strand template. This type of synthesis is called in situ priming. Although in situ priming is normally low, in some duck hepatitis B virus mutants this type of priming is elevated. For example, mutations within the 3' end of the minus-strand DNA can lead to increased levels of in situ priming. We report here that these same mutations result in a second defect, a less efficient template switch that circularizes the genome. Although it is not clear how these mutations affect both steps in DNA replication, our findings suggest a commonality in the mechanism of initiation of plus-strand synthesis and the template switch that circularizes the genome.

Benidipine dilates both pre- and post-glomerular arteriole in the canine kidney

The aim of the present study was to determine the effects of benidipine on renal function and whether benidipine may dilate the efferent arteriole as well as the afferent arteriole of the canine kidney. The effects of benidipine on the renal segmental vascular resistance were estimated using Gomez's formula with some modification. The renal hemodynamic action of benidipine was also compared with that of amlodipine. Intrarenal arterial injection of benidipine at a dose of 3 microg/kg resulted in a significant increase in renal blood flow (RBF), urine flow and urinary excretion of sodium, but not in glomerular filtration rate (GFR). Amlodipine at a dose of 300 microg/kg also increased RBF, urine flow and urinary excretion of sodium to a significant degree equivalent to that by benidipine. However, in contrast to benidipine, amlodipine significantly increased GFR. After the administration of benidipine, autoregulation of RBF and GFR was relatively maintained and the renal perfusion pressure (RPP)-RBF relation shifted upward; that is, RBFs at 75 and 50 mmHg were maintained at a higher level than those of the control. In contrast to benidipine, amlodipine diminished the autoregulation of RBF and GFR. RBFs at 75 and 50 mmHg were not different from those of the control. The afferent and efferent arteriolar resistance (Ra and Re) were calculated based on the RPP-RBF and RPP-GFR relations. Benidipine reduced both Ra and Re, but amlodipine selectively reduced Ra. Benidipine increased RBF but not GFR via the dilation of both afferent and efferent arterioles. Thus, benidipine has unique renal hemodynamic actions which differ from those by most calcium antagonists.

Responses of GLUT4-deficient hearts to ischemia underscore the importance of glycolysis

BACKGROUND

The ischemic heart is dependent on glycolysis for ATP generation, and therapies that increase glucose utilization during ischemia improve survival. Myocardial ischemia results in the translocation of the glucose transporter proteins GLUT1 and GLUT4 to the sarcolemma. The increased glucose entry via these transporters contributes to enhanced glycolysis during ischemia.

METHODS AND RESULTS

To determine the role of GLUT4 in mediating increased glycolytic flux during ischemia, hearts from mice with cardiac-selective GLUT4 deficiency (G4H-/-) were subjected to global low-flow ischemia. During normal perfusion, hearts from fed G4H-/- mice showed increased GLUT1-mediated glucose uptake, higher concentrations of glycogen and phosphocreatine, but delayed recovery after ischemia. When these compensatory changes were eliminated by a 20-hour fast, G4H-/- hearts exhibited depressed glucose utilization during ischemia and developed profound and irreversible systolic and diastolic dysfunction associated with accelerated ATP depletion during ischemia and diminished regeneration of high-energy phosphate compounds on reperfusion.

CONCLUSIONS

GLUT4 is an important mediator of enhanced glycolysis during ischemia and represents an important protective mechanism against ischemic injury.

[Effect of electrical lesion of the area postrema on gastrointestinal interdigestive migrating motor complex in conscious dogs]

OBJECTIVE

To investigate the effect of area postrema (AP) of medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC).

METHODS

Interdigestive MMC activity of antrum and duodenum was recorded by strain gauge implanted on the serosa in 8 conscious dogs. Cannula was intubated in the femoral vein for motilin injection. Plasma motilin concentration was measured by RIA. We observed (1) normal interdigestive MMC activity and fluctuation of plasma motilin concentration; (2) the effect of electrically destroying AP on MMC activity and plasma motilin level and (3) whether or not intravenous injection of motilin could induce phase III contractions after AP was destroyed.

RESULTS

(1) Typical interdigestive MMC with phases I, II, III and IV was recorded in normal dogs. Phase III was concurrent with the peak of plasma motilin level. (2) In dogs electrically destroyed AP with antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase III contractions.

CONCLUSION

Area postrema plays an important role, which is mediated by motilin, on the regulation of interdigestive MMC.

[153Sm-EDTMP in the treatment of bone metastasis of lung cancer]

BACKGROUND

To explore the clinical effect of 153Sm-EDTMP therapy in the treatment of bone metastasis of lung cancer.

METHODS

One hundred and ten patients with painful bone metastasis were entered into this study. The patients were administrated with two steps. At first , they were injected with tracer dose of 153Sm-EDTMP. After a series of index were calculated , such as urine discharge , bone uptake , cumulated skeletal activity , absorbed dose of red marrow and total dose , the second injection was given.

RESULTS

Of 110 cases , 98 (89. 1 %) experienced pain relief with complete response in 38 cases and partial response in 60 ones. Pain relief occurred from 3 h to 4 weeks (7. 5 d +/-6. 3 d) . Duration of pain relief from single injection ranged from 2 to 4 weeks. Follow-up imaging studies were performed within 3 months. In 12 cases , metastatic foci disappeared completely (CR) , Karnofsky score increased by 20 , and analgesic were discontinued. In 20 patients , both number and diameter of metastatic foci decreased (PR) , with an improvement in Karnofsky score ranging from 10 to 15. There were significant decreases in WBC and platelet count found in 35 of 110 patients after therapy , however , blood cell counts returned to baseline within 1 to 3 months.

CONCLUSIONS

153Sm-EDTMP has proven to be a safe and effective therapy for bone pain in lung cancer , and often results in shrinkage or disappearance of metastatic foci.

[The measurement of tracheo-bronchial mucociliary clearance by technetium-99m DTPA aerosol scintigraphy]

Mucociliary clearance of respiratory channels is one of the important mechanisms guarding against retention of foreign particles within the lungs. Thus objective assay of the system is essential to recognizing and understanding its abnormalities. In this study, 18 healthy subjects and 32 patients with chronic obstructive pulmonary diseases (COPD) were examined by technetium-99m-DTPA aerosol scintigraphy. Monitoring was performed by visual inspection (cinescintigraphy) and quantitative analysis. The mucociliary clearance rates of 18 healthy subjects and 32 COPD patients were 3.89 +/- 0.92 mm/min and 1.32 +/- 0.59 mm/min respectively. Statistical analysis indicated that the airway clearance rate and mucociliary clearance rate of COPD patients were significantly lower than those of normal subjects (P < 0.01). The method of assay reported here is simple and objective. It has not only the advantage of visual inspection and quantitative analysis, but also the potential usefulness in studying other bronchial diseases and evaluating therapeutic effectiveness of drugs.

Cardiac hypertrophy with preserved contractile function after selective deletion of GLUT4 from the heart

Glucose enters the heart via GLUT1 and GLUT4 glucose transporters. GLUT4-deficient mice develop striking cardiac hypertrophy and die prematurely. Whether their cardiac changes are caused primarily by GLUT4 deficiency in cardiomyocytes or by metabolic changes resulting from the absence of GLUT4 in skeletal muscle and adipose tissue is unclear. To determine the role of GLUT4 in the heart we used cre-loxP recombination to generate G4H(-/-) mice in which GLUT4 expression is abolished in the heart but is present in skeletal muscle and adipose tissue. Life span and serum concentrations of insulin, glucose, FFAs, lactate, and beta-hydroxybutyrate were normal. Basal cardiac glucose transport and GLUT1 expression were both increased approximately 3-fold in G4H(-/-) mice, but insulin-stimulated glucose uptake was abolished. G4H(-/-) mice develop modest cardiac hypertrophy associated with increased myocyte size and induction of atrial natriuretic and brain natriuretic peptide gene expression in the ventricles. Myocardial fibrosis did not occur. Basal and isoproterenol-stimulated isovolumic contractile performance was preserved. Thus, selective ablation of GLUT4 in the heart initiates a series of events that results in compensated cardiac hypertrophy.

Altered creatine kinase enzyme kinetics in diabetic cardiomyopathy. A(31)P NMR magnetization transfer study of the intact beating rat heart

To determine whether the decreased contractile performance in diabetic hearts is associated with a reduced energy reserve due to decreased creatine kinase (CK) activity, we measured total CK activity (V(max)) in vitro and CK reaction velocity in vivo using(31)P NMR spectroscopy in isolated perfused rat hearts after 4 and 6 weeks of diabetes. After 4 weeks of diabetes, V(max)decreased by 22% with a larger decrease of CK MB than of CK MM and mitochondrial-CK isoenzymes. There was no further decrease in these parameters after 6 weeks of diabetes. Isovolumic contractile performance of 4 and 6 week diabetic hearts, estimated as rate-pressure product under identical perfusion and loading conditions (EDP set at 6-8 mmHg), was only 50% of that of control. ATP, PCr and total creatine concentrations were not different in control and 4 or 6 weeks diabetic rat hearts. After 4 weeks of diabetes, CK reaction velocity decreased by 22%. This was in proportion to the decline of V(max)and therefore predicted by the rate equation for the CK reaction. However, the further decline in the CK reaction velocity after 6 weeks of diabetes (45%) was greater than that predicted from the CK rate equation (17% decrease), and cannot be explained by substrate control of the enzyme. When hearts were inotropically stimulated by increasing perfusate calcium concentration, CK reaction velocity increased slightly (approximately 15%) in both control and diabetic hearts, thereby maintaining a constant ATP concentration. We conclude that in the diabetic myocardium, the CK reaction velocity decreases but does not limit the availability of high-energy phosphates for contraction over the range of workloads studied. We also conclude that a mechanism(s) in addition to substrate control regulates CK reaction velocity in the 6 week diabetic hearts.

Long-term expression of protein kinase C in adult mouse hearts improves postischemic recovery

Activation of protein kinase C (PKC) protects the heart from ischemic injury; however, its mechanism of action is unknown, in part because no model for chronic activation of PKC has been available. To test whether chronic, mild elevation of PKC activity in adult mouse hearts results in myocardial protection during ischemia or reperfusion, hearts isolated from transgenic mice expressing a low level of activated PKCbeta throughout adulthood (beta-Tx) were compared with control hearts before ischemia, during 12 or 28 min of no-flow ischemia, and during reperfusion. Left-ventricular-developed pressure in isolated isovolumic hearts, normalized to heart weight, was similar in the two groups at baseline. However, recovery of contractile function was markedly improved in beta-Tx hearts after either 12 (97 +/- 3% vs. 69 +/- 4%) or 28 min of ischemia (76 +/- 8% vs. 48 +/- 3%). Chelerythrine, a PKC inhibitor, abolished the difference between the two groups, indicating that the beneficial effect was PKC-mediated. (31)P NMR spectroscopy was used to test whether modification of intracellular pH and/or preservation of high-energy phosphate levels during ischemia contributed to the cardioprotection in beta-Tx hearts. No difference in intracellular pH or high-energy phosphate levels was found between the beta-Tx and control hearts at baseline or during ischemia. Thus, long-term modest increase in PKC activity in adult mouse hearts did not alter baseline function but did lead to improved postischemic recovery. Furthermore, our results suggest that mechanisms other than reduced acidification and preservation of high-energy phosphate levels during ischemia contribute to the improved recovery.

Thermodynamic limitation for Ca2+ handling contributes to decreased contractile reserve in rat hearts

The free energy release from ATP hydrolysis (|DeltaG approximately p|) is decreased by inhibiting the creatine kinase (CK) reaction, which may limit the thermodynamic driving force for the sarcoplasmic reticulum (SR) Ca2+ pumps and thereby cause a decrease in contractile reserve. To determine whether a decrease in |DeltaG approximately p| results in decreased contractile reserve by impairing Ca2+ handling, we measured left ventricular pressure and cytosolic Ca2+concentration ([Ca2+]c; by indo 1 fluorescence) in isolated perfused rat hearts, with >95% inhibition of CK with 90 micromol iodoacetamide. Iodoacetamide did not directly alter SR Ca2+-ATPase activity, baseline left ventricular developed pressure, or baseline [Ca2+]c. When perfusate Ca2+ concentration was increased from 1.2 to 3.3 mM, LV developed pressure increased from 67 +/- 6 to 119 +/- 8 mmHg in control hearts (P < 0.05) but did not significantly increase in CK-inhibited hearts. Similarly, the amplitude of the [Ca2+]c transient increased from 548 +/- 54 to 852 +/- 140 nM in control hearts (P < 0.05) but did not significantly increase in CK-inhibited hearts. We conclude that decreased |DeltaG approximately p| limits intracellular Ca2+ handling and thereby limits contractile reserve.

Changing the site of initiation of plus-strand DNA synthesis inhibits the subsequent template switch during replication of a hepadnavirus

Unique to hepadnavirus reverse transcription is the process of primer translocation, in which the RNA primer for the initiation of plus-strand DNA synthesis is generated at one site on its template, DR1, and is moved to a new site, DR2. For duck hepatitis B virus (DHBV), DR2 is located within 50 nucleotides of the 5' end of the minus-strand DNA template. When the synthesis of plus-strand DNA proceeds to the 5' terminus of the minus strand, the 3' end of the minus strand becomes the template for DNA synthesis. This switch in templates circularizes the nascent genome and is required for the genesis of the relaxed circular form of the DNA and the mature capsid. Maturation of the capsid is a prerequisite for virus egress. We have analyzed a series of DHBV variants in which plus-strand DNA synthesis was initiated from a new position relative to the 5' end of the template. For these variants, the subsequent circularization was inhibited. We found that when the number of nucleotides between the site of initiation of plus-strand DNA synthesis and the 5' end of its template was restored to 54 nucleotides, circularization was substantially restored. These results mean that the process of circularization is influenced by the earlier steps in DNA replication. This sensitivity is consistent with the notion that this region of the nascent genome is in a dynamic structure that is crucial for successful DNA replication.