The role of metformin and statins in the incidence of epithelial ovarian cancer in type 2 diabetes: a cohort and nested case-control study.

OBJECTIVE: To obtain evidence of the effects of metformin and statins on the incidence of ovarian cancer in women with type 2 diabetes (T2D). DESIGN: A retrospective cohort study and nested case-control study. SETTING: The data were obtained from a diabetes database (FinDM) combining information from several nationwide registers. POPULATION: A cohort of 137 643 women over 40 years old and diagnosed with T2D during 1996-2011 in Finland. METHODS: In full cohort analysis Poisson regression was used to estimate the hazard ratios (HR) in relation to ever use of metformin, insulin other oral anti-diabetic medication or statins. In the nested case-control analysis 20 controls were matched to each case of ovarian cancer. Conditional logistic regression was used to estimate HRs in relation to medication use and cumulative use of different medications. The estimates were adjusted for age and duration of T2D. MAIN OUTCOME MEASURE: Incidence of ovarian cancer. RESULTS: In all, 303 women were diagnosed with ovarian cancer during the follow up. Compared with other forms of oral anti-diabetic medication, metformin (HR 1.02, 95% CI: 0.72-1.45) was not found to be associated with the incidence of ovarian cancer. Neither was there evidence for statins to affect the incidence (HR 0.99, 95% CI: 0.78-1.25). In nested case-control analysis the results were essentially similar. CONCLUSIONS: No evidence of an association between the use of metformin or statins and the incidence of ovarian cancer in women with T2D was found. TWEETABLE ABSTRACT: No evidence found for metformin or statins reducing the incidence of ovarian cancer.

Cause-specific mortality in endometrioid endometrial cancer patients with type 2 diabetes using metformin or other types of antidiabetic medication.

AIM: To obtain further evidence of the association between metformin or other types of antidiabetic medication (ADM) and mortality from endometrial cancer (EC) and other causes of death in patients with endometrioid EC and type 2 diabetes (T2D). MATERIALS AND METHODS: A retrospective cohort of women with existing T2D and diagnosed with endometrioid EC from 1998 to 2011, obtained from a nationwide diabetes database (FinDM), were included in the study. Cumulative mortality from EC and that from other causes was described by using the Aalen-Johansen estimator. Cause-specific mortality rates were analyzed by using Cox models, and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of ADM during the three-year period preceding EC diagnosis. RESULTS: From the FinDM cohort we identified 1215 women diagnosed with endometrioid EC, of whom 19% were metformin users, 12% were users of other types of oral antidiabetic medication, 25% used other types of oral antidiabetic medication plus metformin, 26% used insulin and 14% had no antidiabetic medication. Mortality from EC was not found to be different in women using metformin (HR 0.89, 95% Cl 0.52-1.54) but mortality from other causes was lower (HR 0.52, 95% Cl 0.31-0.88) compared with women using other types of oral ADM. CONCLUSIONS: Our findings are inconclusive as to the possible effect of metformin on the prognosis of endometrioid EC in women with T2D. However, use of metformin may reduce mortality from other causes.

Semisolid meal enriched in oat bran decreases plasma glucose and insulin levels, but does not change gastrointestinal peptide responses or short-term appetite in healthy subjects.

BACKGROUND AND AIMS: Dietary fibre (DF) may play an important role in weight control. The amount, type and way of processing of DF modify food structure and subsequent postprandial appetitive, metabolic and hormonal effects, but current understanding about the magnitude of effects that specific types and amounts of DF exert are still poorly understood. METHODS AND RESULTS: We investigated the effects of wheat and oat brans alone and as combination in semisolid food matrix on postprandial appetite profile and gastrointestinal (GI) hormonal responses. Twenty healthy, normal-weight subjects (5 male/15 female, aged 23.3 ± 0.85y) participated in the study. Isoenergetic and isovolumic (1250 kJ, 300 g) puddings with different insoluble and soluble DF content were tested in a randomised order: pudding with 1) no added fibre, 2) 10 g wheat bran DF, 3) 10 g oat bran DF and 4) combination including 5 g wheat bran DF + 5 g oat bran DF. Blood samples were drawn before and 15, 30, 45, 60, 90, 120 and 180 min after the test meals to determine plasma glucose, ghrelin, peptide YY (PYY) and serum insulin concentrations. Subjective profiles of appetite were assessed using visual analogue scales (VAS). Plasma glucose (P = 0.001) and serum insulin (P < 0.001) responses were the lowest after the pudding with the greatest amount of ß-glucan. In contrast, postprandial ghrelin or PYY responses or appetite sensations did not differ among the meals. CONCLUSION: Oat ß-glucan decreased postprandial plasma glucose and serum insulin responses, yet had no significant effects on GI peptide responses or appetite ratings.

GATA4 mediates activation of the B-type natriuretic peptide gene expression in response to hemodynamic stress.

To identify the mechanisms that couple hemodynamic stress to alterations in cardiac gene expression, DNA constructs containing the rat B-type natriuretic peptide (BNP) promoter were injected into the myocardium of rats, which underwent bilateral nephrectomy or were sham-operated. Ventricular BNP mRNA levels were induced about 4-fold; and the BNP reporter construct containing the proximal 2200 bp, 5-fold, in response to 1-d nephrectomy. Deletion of sequences between bp -2200 and -114 did not affect basal or inducible activity of the BNP promoter. An activator protein-1-like site and two tandem GATA elements are located within this 114-bp sequence. Both deletion and mutation of the AP-1-like motif decreased basal activity but did not abolish the response to nephrectomy. In contrast, mutation or deletion of -90 bp GATA-sites abrogated the response to hemodynamic stress. The importance of these GATA elements to BNP promoter activation was further confirmed by the corresponding 38-bp oligonucleotide conferring hemodynamic stress responsiveness to a minimal BNP promoter. In gel mobility shift assays, nephrectomy increased left ventricular BNP GATA4 binding activity significantly. In conclusion, GATA elements are necessary and sufficient to confer transcriptional activation of BNP gene in response to hemodynamic stress.

Mechanical load-induced alterations in B-type natriuretic peptide gene expression.

Atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide are the known members of the mammalian natriuretic peptide system. Like ANP, BNP is a natriuretic and diuretic hormone that also causes peripheral vasodilation and inhibition of the sympathetic and renin-angiotensin systems. Although originally isolated from porcine brain, the BNP gene is expressed in a specific manner in cardiac myocytes in both the atria and the ventricles, but it is mainly released from the ventricles. The major determinant of BNP secretion is wall stretch, and the levels of BNP mRNA increase substantially in response to cardiac overload. In the clinical setting, BNP appears to be the most powerful neurohumoral predictor of left-ventricular function and prognosis. An acute increase in BNP gene expression occurs within 1 h and mimics the rapid induction of proto-oncogenes in response to hemodynamic stress. BNP can be used as a myocyte-specific marker to identify mechanisms that couple acute mechanical overload to alterations in cardiac gene expression. This paper is focused on the mechanisms that regulate BNP gene expression in cardiac overload. Particularly, autocrine-paracrine factors as well as cytoplasmic signaling pathways and transcription factors involved in mechanical stretch-induced BNP gene expression are discussed.

Human peroxisomal multifunctional enzyme type 2. Site-directed mutagenesis studies show the importance of two protic residues for 2-enoyl-CoA hydratase 2 activity.

Beta-oxidation of acyl-CoAs in mammalian peroxisomes can occur via either multifunctional enzyme type 1 (MFE-1) or type 2 (MFE-2), both of which catalyze the hydration of trans-2-enoyl-CoA and the dehydrogenation of 3-hydroxyacyl-CoA, but with opposite chiral specificity. Amino acid sequence alignment of the 2-enoyl-CoA hydratase 2 domain in human MFE-2 with other MFE-2s reveals conserved protic residues: Tyr-347, Glu-366, Asp-370, His-406, Glu-408, Tyr-410, Asp-490, Tyr-505, Asp-510, His-515, Asp-517, and His-532. To investigate their potential roles in catalysis, each residue was replaced by alanine in site-directed mutagenesis, and the resulting constructs were tested for complementation in a yeast. After additional screening, the wild type and noncomplementing E366A and D510A variants were expressed and characterized. The purified proteins have similar secondary structural elements, with the same subunit composition. The E366A variant had a k(cat)/K(m) value 100 times lower than that of the wild type MFE-2 at pH 5, whereas the D510A variant was inactive. Asp-510 was imbedded in a novel hydratase 2 motif found in the hydratase 2 proteins. The data show that the hydratase 2 reaction catalyzed by MFE-2 requires two protic residues, Glu-366 and Asp-510, suggesting that their catalytic role may be equivalent to that of the two catalytic residues of hydratase 1.

Yeast peroxisomal multifunctional enzyme: (3R)-hydroxyacyl-CoA dehydrogenase domains A and B are required for optimal growth on oleic acid.

The yeast peroxisomal (3R)-hydroxyacyl-CoA dehydrogenase/2-enoyl-CoA hydratase 2 (multifunctional enzyme type 2; MFE-2) has two N-terminal domains belonging to the short chain alcohol dehydrogenase/reductase superfamily. To investigate the physiological roles of these domains, here called A and B, Saccharomyces cerevisiae fox-2 cells (devoid of Sc MFE-2) were taken as a model system. Gly(16) and Gly(329) of the S. cerevisiae A and B domains, corresponding to Gly(16), which is mutated in the human MFE-2 deficiency, were mutated to serine and cloned into the yeast expression plasmid pYE352. In oleic acid medium, fox-2 cells transformed with pYE352:: ScMFE-2(aDelta) and pYE352::ScMFE-2(bDelta) grew slower than cells transformed with pYE352::ScMFE-2, whereas cells transformed with pYE352::ScMFE-2(aDeltabDelta) failed to grow. Candida tropicalis MFE-2 with a deleted hydratase 2 domain (Ct MFE- 2(h2Delta)) and mutational variants of the A and B domains (Ct MFE- 2(h2DeltaaDelta), Ct MFE- 2(h2DeltabDelta), and Ct MFE- 2(h2DeltaaDeltabDelta)) were overexpressed and characterized. All proteins were dimers with similar secondary structure elements. Both wild type domains were enzymatically active, with the B domain showing the highest activity with short chain and the A domain with medium and long chain (3R)-hydroxyacyl-CoA substrates. The data show that the dehydrogenase domains of yeast MFE-2 have different substrate specificities required to allow the yeast to propagate optimally on fatty acids as the carbon source.

Augmentation of BNP gene expression in atria by pressure overload in transgenic rats harbouring human renin and angiotensinogen genes.

We studied the role of angiotensin II in pressure overload-induced B-type natriuretic peptide (BNP) gene expression by using a double transgenic rat (dTGR) model, in which transgenic rats for the human angiotensinogen and renin genes are crossed. Pressure overload produced by [Arg8]-vasopressin (AVP) infusion (i.v., 0.05 microg/kg/min for 2 h) in conscious, chronically instrumented rats, resulted in a significantly greater increase in BNP mRNA levels in the left atrium of the dTGR rats than in Sprague-Dawley (SD) control rats (3.6- vs 1.6-fold, p < 0.05), while in the left ventricle there was no significant difference between the strains. In dTGR rats, the early activation of the BNP gene expression was associated with a decrease in immunoreactive BNP levels in the atrium (27.5%, p < 0.05), but not in the ventricle. In SD rats, ir-BNP levels did not change significantly in either atria or ventricles in response to AVP infusion. These results show that the pressure overload-induced activation of BNP gene expression differs between atrial and ventricular myocytes in the dTGR model of experimental hypertension.

B-type natriuretic peptide: a myocyte-specific marker for characterizing load-induced alterations in cardiac gene expression.

Atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and C-type natriuretic peptide are the known members of the mammalian natriuretic peptide system. ANP and BNP genes are expressed in a specific manner in cardiac myocytes. They are natriuretic and diuretic hormones and cause vasorelaxation. ANP is mainly synthesized in the atria of the normal adult heart. However, ventricular hypertrophy is characterized by an augmentation of the synthesis and release of ANP from the ventricles. BNP is expressed in both the atria and the ventricles, but is mainly released from the ventricles. The major determinant of ANP and BNP secretion is wall stretch, and the levels of BNP messenger RNA increase substantially in response to cardiac overload. Acute increase in BNP gene expression occurs within 1 h and mimics the rapid induction of proto-oncogenes in response to haemodynamic stress. BNP can be used as a myocyte-specific marker to identify mechanisms that couple acute mechanical overload to alterations in cardiac gene expression.

Coronary pressure as a determinant of B-type natriuretic peptide gene expression in isolated perfused adult rat heart.

The role of coronary flow in the regulation of ventricular B-type natriuretic peptide (BNP) gene expression was studied in isolated perfused rat heart preparation. The increase of coronary flow from 5 ml/min to 20 ml/min for 2 h resulted in a 132+/-6 mm Hg increase in aortic perfusion pressure. The changes in BNP mRNA and immunoreactive BNP (IR-BNP) levels in response to hemodynamic stress were compared to those of c-fos and adrenomedullin (ADM) gene expression. The increase of coronary flow resulted in 1.5-fold increases in the left ventricular BNP mRNA (P < 0.001) and IR-BNP (P < 0.05) levels in 2-month old rats. There was also a 1.5-fold (P < 0.05) increase in ventricular c-fos mRNA levels, whereas ADM mRNA levels decreased by 74% (P < 0.001) in the left ventricle. In 18-month old rats, the increase in coronary flow decreased left and right ventricular BNP mRNA levels by 18% (P < 0.05) and 39% (P < 0.001), respectively. There were no changes in IR-BNP peptide and c-fos mRNA levels, whereas ADM mRNA levels decreased by 46% (P < 0.001) in the left ventricles. The results show that increased aortic perfusion pressure results in differential expression of cardiac genes including up-regulation of ventricular BNP and c-fos gene expression and down-regulation of ADM gene expression. Furthermore, aging seems to elevate the threshold at which hemodynamic stress of the heart results in a response at BNP gene level.

Endothelin-1 is involved in stretch-induced early activation of B-type natriuretic peptide gene expression in atrial but not in ventricular myocytes: acute effects of mixed ET(A)/ET(B) and AT1 receptor antagonists in vivo and in vitro.

BACKGROUND: The precise role of paracrine and autocrine factors in mechanical load-induced activation of cardiac gene expression is unknown. Here we report the effects of endothelin-1 (ET-1) and angiotensin II (Ang II) receptor antagonism on acute pressure overload-induced activation of cardiac B-type natriuretic peptide (BNP) gene expression in spontaneously hypertensive rats (SHRs) in vivo and on mechanical stretch-induced increase in atrial BNP gene expression in vitro. METHODS AND RESULTS: Acute pressure overload produced in conscious SHRs by infusion of arginine8-vasopressin (0.05 microg x kg(-1) x min(-1)) for 2 hours resulted in an increase in BNP mRNA levels in the left ventricle as well as in the atrium. Bolus injections of bosentan (mixed ET(A)/ET(B) receptor antagonist, 10 mg/kg I.V.) but not losartan (AT1 receptor antagonist, 10 mg/kg I.V.) blocked the increase of the BNP mRNA levels produced by pressure overload in the left atria, whereas the elevation of BNP mRNA levels was similar (a 1.9-fold increase) in the left ventricles of vehicle-, losartan-, and bosentan-infused SHRs. In an isolated perfused rat heart preparation, infusion of bosentan (1 micromol/L) for 2 hours inhibited the mechanical stretch-induced increase in BNP mRNA levels in the right atria, whereas an AT1 receptor antagonist, CV-11974 (10 nmol/L), had no effect. CONCLUSIONS: The findings of the present study demonstrate that Ang II and ET-1 are not obligatorily required for stretch to trigger the increased BNP gene expression in ventricular myocytes in vivo. In contrast, mechanical load on the atrial myocytes did initiate an ET-1-dependent expression of BNP gene showing that endogenous ET-1 production differentially regulates BNP gene expression in atrial and ventricular myocytes.

Involvement of transcriptional and posttranscriptional mechanisms in cardiac overload-induced increase of B-type natriuretic peptide gene expression.

The induction of atrial and ventricular B-type natriuretic peptide (BNP) gene expression is one of the earliest events occurring during hemodynamic overload. To examine the molecular mechanisms for increased BNP gene expression during cardiac overload, we studied the induction of the BNP gene expression compared with that of atrial natriuretic peptide (ANP) in a modified perfused rat heart preparation. An increase in right atrial pressure of 5 mm Hg resulted in a 1.4-fold (P < .05) and 2.2-fold (P < .01) increase in BNP mRNA levels after 1 and 2 hours, respectively, whereas ANP mRNA levels remained unchanged. Stretching for up to 2 hours also significantly increased right atrial immunoreactive BNP (ir-BNP) levels (from 15.8 +/- 2.2 to 20.1 +/- 1.2 ng/mg, P < .05). Actinomycin D (10 micrograms/mL), a transcriptional inhibitor, completely inhibited the stretch-induced increase in atrial BNP mRNA levels at 1 hour (P < .05) and 2 hours (P < .001), whereas a protein synthesis inhibitor, cycloheximide (90 micrograms/mL), had no effect on basal or direct mechanical stretch-induced increase in right atrial BNP mRNA levels. Furthermore, we examined the role of tyrosine kinase and protein kinase C activities in acute mechanical stretch-induced increase in BNP synthesis. Tyrosine kinase inhibitors lavendustin A (1 mumol/L) and tyrphostin A25 (3 mumol/L) and protein kinase C inhibitors staurosporine (30 nmol/L) and chelerythrine (1 mumol/L) prevented the stretch-induced increase in right atrial ir-BNP concentrations at 2 hours. In addition, chelerythrine inhibited the increase of right atrial BNP mRNA levels stimulated by cardiac overload. These resuls demonstrate that the early increase of BNP mRNA levels by mechanical stretch results from increased transcriptional activation and is independent of protein synthesis. Our results also suggest that protein kinase C and tyrosine kinases activities may be involved in coupling cardiac overload to alterations in atrial BNP synthesis.

Adrenomedullin gene expression in the rat heart is stimulated by acute pressure overload: blunted effect in experimental hypertension.

The levels of adrenomedullin (ADM), a newly discovered vasodilating and natriuretic peptide, are elevated in plasma and ventricular myocardium in human congestive heart failure suggesting that cardiac synthesis may contribute to the plasma concentrations of ADM. To examine the time course of induction and mechanisms regulating cardiac ADM gene expression, we determined the effect of acute and short-term cardiac overload on ventricular ADM mRNA and immunoreactive ADM (ir-ADM) levels in conscious rats. Acute pressure overload was produced by infusion of arginine8-vasopressin (AVP, 0.05 microg/kg/min, i.v.) for 2 h into 12-week-old hypertensive TGR(mREN-2)27 rats and normotensive Sprague-Dawley (SD) rats. Hypertension and marked left ventricular hypertrophy were associated with 2.2-times higher ir-ADM levels in the left ventricular epicardial layer (178 +/- 36 vs. 81 +/- 23 fmol/g, P<0.05) and 2.6-times higher ir-ADM levels in the left ventricular endocardial layer (213 +/- 23 vs. 83 +/- 22 fmol/g, P<0.01). The infusion of AVP for 2 h in normotensive rats produced rapid increases in the levels of left ventricular ADM mRNA (epicardial layer: 1.6-fold, P<0.05) and ir-ADM (endocardial layer: from 83 +/- 22 to 140 +/- 12 fmol/g, P<0.05), whereas ventricular ADM mRNA and ir-ADM levels did not change significantly in hypertensive rats. Short-term cardiac overload, induced by administration of angiotensin II (33.3 microg/kg/h, s.c., osmotic minipumps) for two weeks in normotensive SD rats resulted in left ventricular hypertrophy (3.05 +/- 0.17 vs. 2.75 +/- 0.3 mg/g, P<0.05) and a 1.5-fold increase (P<0.05) in ventricular ADM mRNA levels. In conclusion, the present results show that pressure overload acutely stimulated ventricular ADM gene expression in conscious normotensive rats suggesting a potential beneficial role for endogenous ADM production in the heart against cardiac overload. Since pressure overload-induced increase in ADM synthesis was attenuated in hypertensive rats, alterations in the ADM system may contribute to the pathogenesis of hypertension in the TGR(mREN-2)27 rat.

Synthesis and secretion of natriuretic peptides in the hypertensive TGR(mREN-2)27 transgenic rat.

To examine the pathophysiological mechanisms in transgenic rats carrying the murine Ren-2d renin gene, we studied atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) gene expression and secretion in 12-week-old hypertensive TGR(mREN-2)27 and normotensive Sprague-Dawley rats. Hypertension and marked left ventricular hypertrophy in TGR(mREN-2)27 rats were associated with high baseline plasma levels of immunoreactive ANP (148 +/- 18 versus 34 +/- 3 pmol/L, hypertensive versus normotensive rats; P < .001), whereas plasma immunoreactive BNP levels did not differ significantly between the strains (19 +/- 4 versus 12 +/- 3 pmol/L, P = .06). ANP mRNA and immunoreactive ANP levels in the left ventricular endocardial and epicardial layers in TGR(mREN-2)27 rats were about 20 to 40 times higher (P < .001) than those in normotensive rats. There were no statistically significant differences between atrial and ventricular BNP mRNA levels, but left ventricular immunoreactive BNP concentrations were twofold higher in hypertensive TGR(mREN-2)27 than in normotensive rats. Infusion of [Arg8]-vasopressin (0.05 microgram/kg per minute IV, for 2 hours) in normotensive rats produced rapid increases (twofold, P < .05 to .01) in left ventricular BNP mRNA and immunoreactive BNP levels, whereas ventricular BNP mRNA and peptide levels did not change significantly in hypertensive rats. The increase in left atrial BNP mRNA levels in response to acute pressure overload was also significantly smaller in the hypertensive than normotensive rats (3.5-fold versus 5.2-fold, P < .01). Furthermore, the proportional but not absolute (in picomoles per liter) increase in plasma immunoreactive ANP was smaller in transgenic rats in response to acute saline and [Arg8]-vasopressin infusions (0.9% NaCl: 1.9-fold increase versus 4.4-fold increase in normotensive rats, P < .001; [Arg8]-vasopressin: 2.2-fold versus 4.8-fold increase, P < .001). These results show that baseline and cardiac overload-induced increases in BNP synthesis are markedly attenuated in transgenic rats carrying the murine Ren-2d renin gene. In addition, acute volume and pressure overload produced a smaller proportional increase in ANP secretion in hypertensive rats than normotensive rats. These alterations in the natriuretic peptide system may contribute to the pathogenesis of hypertension and cardiovascular complications in the TGR(mREN-2)27 rat.

A double-blind study comparing the efficacy and tolerability of mirtazapine and doxepin in patients with major depression.

One hundred and sixty-three patients with major depression were randomly assigned to treatment with mirtazapine or doxepin for 6 weeks in a double-blind clinical trial. Initially, patients received mirtazapine 20 mg/day or doxepin 75 mg/day; dosages were then titrated up to a maximum of 60 mg/day and 300 mg/day, respectively. Both drugs produced considerable improvement in depressive symptoms with no statistically significant differences between the two patient groups. In the mirtazapine group only two patients prematurely terminated the study due to adverse drug experiences, as compared to six in the doxepin-treated group. Moreover, doxepin-treated patients complained more frequently of dry mouth and movement disorders. In conclusion, mirtazapine is an effective treatment for major depression and appears to offer advantages in tolerability over doxepin.

Transgenic barley (Hordeum vulgare L.) by electroporation of protoplasts.

Protoplasts isolated from calli derived from cultured microspores of barley (Hordeum vulgare L. cv. Kymppi, an elite cultivar) were transformed with the neomycin phosphotransferase marker gene (nptII) by electroporation. Screening of the regenerated plants for the NPTII activity by gel assay resulted in three positive signals. Southern blot analysis and NPTII assays of second and third generation plants confirmed the genomic integration of the transferred gene and that the new trait was inherited by the progeny.

Efficient regeneration of fertile plants from protoplasts isolated from microspore cultures of barley (Hordeum vulgare L.).

Cultures of isolated microspores of barley (Hordeum vulgare L. cv. Kymppi, an elite cultivar of malting barley) were used for isolation of protoplasts. The protoplasts were cultured embedded in agarose. The plating efficiency varied from 0.002% to 0.015%. Several hundred green plants were regenerated from the cultures. Plantlets regenerated from protoplasts were potted in soil within 4-5 months of collecting the spikes for microspore culture and the first plants are now setting seed.

Brain natriuretic peptide in plasma, atria, and ventricles of vasopressin- and phenylephrine-infused conscious rats.

To evaluate the mechanisms of brain natriuretic peptide (BNP) gene expression, we determined the effect of acute cardiac overload (from 30 min to 4 h) on atrial and ventricular BNP mRNA levels in normal and hypertrophied myocardium. Arginine8 vasopressin (AVP; 0.05 microgram/kg.min) and l-phenylephrine (PHE; 20 micrograms/kg.min) were infused iv to increase cardiac workload in conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. At the age of 10-22 months, during the established phase of ventricular hypertrophy, baseline BNP synthesis was increased in the hypertrophic ventricular cells of SHR, as reflected by about 2-fold (P < 0.05-0.001) elevation of levels of immunoreactive BNP (IR-BNP) and BNP mRNA. Intravenous infusions of AVP and PHE increased mean arterial pressure, plasma IR-BNP levels, and ventricular BNP mRNA levels within 1 h of pressure overload; peak levels of BNP mRNA were reached at 4 h. The increase in BNP mRNA levels was slightly greater in the epicardial (2.0- to 2.6-fold; P < 0.01) than in the endocardial layer (1.9- to 2.0-fold; P < 0.01) of the left ventricle. The rapid stimulation of ventricular BNP mRNA synthesis induced by AVP and PHE was accompanied by the simultaneous activation of left atrial BNP gene expression. Left atrial BNP mRNA levels were increased significantly in response to 1-h infusions, and values peaked in both the AVP- and PHE-infused SHR at 2 h, i.e. a 3.6-fold increase in BNP mRNA levels in left atria in AVP-infused SHR, and a 2.5-fold increase in PHE-infused SHR. Right atrial BNP mRNA levels remained unchanged during drug infusion, except for a transient increase in the WKY after 30 min of infusion. The induction of BNP synthesis was also reflected by increased ventricular IR-BNP levels, whereas AVP and PHE did not affect atrial IR-BNP concentrations or contents. In conclusion, the present study shows that pressure overload rapidly stimulates BNP gene expression in the hearts of normal and hypertensive rats. Thus, locally generated BNP in the heart muscle may play a significant role in cardiac adaptation to acute changes in mechanical load.

Fertile transgenic barley to particle bombardment of immature embryos.

Transgenic, fertile barley (Hordeum vulgare L.) from the Finnish elite cultivar Kymppi was obtained by particle bombardment of immature embryos. Immature embryos were bombarded to the embryonic axis side and grown to plants without selection. Neomycin phosphotransferase II (NPTII) activity was screened in small plantlets. One out of a total of 227 plants expressed the transferred nptII gene. This plant has until now produced 98 fertile spikes (T0), and four of the 90 T0 spikes analyzed to date contained the nptII gene. These shoots were further analyzed and they expressed the transferred gene. From green grains, embryos were isolated and grown to plantlets (T1). The four transgenic shoots of Toivo (the T0 plant) produced 25 plantlets as T1 progeny. Altogether fifteen of these T1 plants carried the transferred nptII gene as detected with the PCR technique, fourteen of which expressed the nptII gene. The integration and inheritance of the transferred nptII gene was confirmed by Southern blot hybridization. Although present as several copies, the transferred gene was inherited as a single Mendelian locus into the T2 progeny.

Atrial stretch induces rapid increase in brain natriuretic peptide but not in atrial natriuretic peptide gene expression in vitro.

Pressure and volume overload in vivo is characterized by induction of the expression of two cardiac hormones, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), but whether stretch directly or other pathophysiological factors associated with cardiac overload cause the activation of these genes is not known. In the present study we examined the effect of short-term (from 30 min to 2 h) direct myocardial stretch on atrial ANP and BNP synthesis and release in modified perfused rat heart preparation that enabled the stepwise distension of the right atrium by pressures approximating those found in vivo. The increase in right atrial pressure by 3.6 mm Hg for 2 h resulted in a 3.3- (p < 0.001) and 1.7-fold (p < 0.02) increase in the rate of IR-ANP and IR-BNP release, respectively, into the perfusate. The maximal increase in both ANP and BNP release was seen after 20 min distension. Thereafter the perfusate IR-ANP and IR-BNP concentration gradually decreased, reaching control values within 2 hours. Chromatographic analysis showed that the hearts primarily release the active, processed 28- and 45-amino acid ANP- and BNP-like peptides, respectively, both before and during atrial stretch. Atrial stretch induced rapid stimulation of BNP gene expression: 1.9- (p < 0.001) and 4.5-fold (p < 0.001) increase in right auricular BNP mRNA levels after 1.0 and 2.0 hours' stretching, respectively, was found on Northern blot analysis, while no change was seen after 30 min distension. In contrast, stretching for up to 2 h did not change auricular ANP mRNA, IR-ANP or IR-BNP levels. Our results show for the first time that atrial stretch induces rapid stimulation of both synthesis and secretion of BNP. The induction of BNP gene expression in the very early stages of cardiac overload mimics the induction of protooncogenes and occurred without involvement of humoral or neural factors. The lack of response of atrial ANP mRNA levels demonstrates that the regulation of BNP gene expression differs from that of ANP.