Biomedical subjects

A Salvetti

Publications and source records attributed to A Salvetti.

At least 37 records · Page 2Linked to original sources

PubMed2001

Effects of beta-naphthoflavone on the cytochrome P450 system, and phase II enzymes in gilthead seabream (Sparus aurata).

The effect of beta-naphthoflavone (beta-NF) on several catalytic activities of cytochrome P450 (CYP) and phase II enzymes putatively controlled by [Ah]-receptor activation in the liver, heart and kidney of gilthead seabream, was investigated. In the liver, beta-NF treatment [intraperitoneal injection (i.p.) 50 mg/kg] resulted in an increase of CYP content, immunoreactive CYP 1A and methoxyresorufin-O-demethylase (MEROD), pentoxyresorufin O-depentylase (PROD) and ethoxyresorufin-O-deethylase (EROD) activities. However, beta-NF had no effect on any of the hepatic phase II enzymes examined (benzaldehyde dehydrogenase, propionaldehyde dehydrogenase, glutathione S-transferase, UDP-glucuronyl-transferase, DT-diaphorase). Single i.p. injection of 10 mg/kg beta-NF showed a maximal induction of CYP 1A-like protein and EROD activity after 3-7 days. CYP 1A and EROD returned to control levels 18-days post-treatment. beta-NF injection also caused a rapid increase of a single band size of mRNA recognized by a CYP 1A1 cDNA fragment from sea bass (Dicentrarchus labrax). Expression of mRNA preceded the increase of EROD activity and declined rapidly by 96 h. Dose-response experiments demonstrated that EROD was significantly enhanced in liver by a single injection of 0.3 mg/kg beta-NF and was the most sensitive measurement for CYP 1A-like induction. beta-NF treatments also increased the expression of CYP 1A-like protein, mRNA and EROD, but not MEROD and PROD activities in heart and kidney.

Animals↗

PubMed2001

Role of endothelin in the control of peripheral vascular tone in human hypertension.

Endothelins are potent 21 amino acid vasoconstrictor isopeptides produced in different vascular tissues, including vascular endothelium. Endothelin-1 is the main endothelin generated by the endothelium and probably the most important in the cardiovascular system. Endothelin-1 acts through specific receptors termed ET(A), represented only on smooth muscle cells and having the function of growth promotion and mediating contractions, and ET(B), located both on smooth muscle cells, where they evoke contractions, and on endothelial cells, inducing relaxation by production of the endothelium-derived relaxing factor nitric oxide. In physiological conditions endothelin-1 administration causes vasodilation and vasoconstriction at low and high concentrations, respectively. However, administration of mixed ET(A)/(B) receptor antagonists causes slight or absent vasodilation, indicating that the direct vasoconstrictor effect of the peptide is probably masked by ET(B)-induced NO-dependent vasodilation. In essential hypertensive patients, the activity of exogenous endothelin-1 is either increased, similar or decreased as compared to normotensive subjects, depending on which vascular district or scheme of administration is considered. But although available evidence does not indicate increased endothelin-1 plasma levels in patients with essential hypertension, simultaneous antagonism of ET(A)/(B) receptors causes a greater degree of vasodilation in hypertensives than in normotensive subjects. Moreover administration of a selective ET(B) receptor antagonist causes vasoconstriction in normotensive subjects and vasodilation in essential hypertensive patients. Finally, the vasodilating effect of a mixed ET(A)/(B) receptor antagonist is inversely related to NO availability. Taken together these findings suggest that essential hypertension is characterized by increased endothelin-1 vasoconstrictor tone. This alteration seems to be dependent on decreased endothelial ET(B)-mediated NO production attributable to impaired NO availability. In such conditions endothelial ET(B)-induced vasodilation no longer compensates for the direct classical endothelin vasoconstrictor effect mediated by smooth muscle cell ET(A) and ET(B) receptors. Therefore endothelin-1 could potentially be involved in the pathogenesis of essential hypertension or of its complications, and blockade of this system is a fascinating new target for therapeutic intervention in this disease.

Endothelin Receptor Antagonists↗

PubMed2001

Effect of acute blood pressure reduction on endothelial function in the brachial artery of patients with essential hypertension.

OBJECTIVES: To evaluate the effect of acute blood pressure reduction on endothelium-dependent vasodilation in the peripheral circulation of essential hypertensive patients. DESIGN: A parallel group study; endothelial function measured in 64 essential hypertensive patients before and after (2 h) treatment with nifedipine (20 mg, n = 32) or captopril (50 mg, n = 32), p.o., randomly assigned. METHODS: In hypertensive patients, we evaluated flow-mediated, endothelium-dependent dilation (FMD, high resolution ultrasound) of the brachial artery compared with endothelium-independent response to glyceryl trinitrate (GTN, 25 microg s.l.). Automatic computerized analysis was used to measure brachial artery diameter on end-diastolic frames acquired every second during the study. Sixty-six healthy normotensive subjects were also evaluated to assess the presence of endothelial dysfunction in hypertensive patients. RESULTS: Hypertensive patients showed a significantly (P< 0.01) lower FMD (5.9 +/- 2.5%) as compared to healthy controls (7.7 +/- 3.8%). The response to GTN was similar in normotensive subjects (7.5 +/- 3.1%) and hypertensive patients (7.2 +/- 6.5%). At baseline brachial artery diameter, FMD and response to GTN were similar in the nifedipine- and captopril-treated groups. Nifedipine and captopril similarly reduced blood pressure, but only nifedipine increased heart rate. Acute nifedipine, but not captopril, significantly (P< 0.01) increased brachial artery diameter, while FMD and response to GTN were not modified after nifedipine or captopril. CONCLUSIONS: Endothelial dysfunction in the brachial artery of essential hypertensive patients is not improved by acute blood pressure reduction.

Adult↗

PubMed2001

Effect of calcium antagonist or beta blockade treatment on nitric oxide-dependent vasodilation and oxidative stress in essential hypertensive patients.

OBJECTIVES: Essential hypertension is associated with impaired endothelium-dependent vasodilation caused by oxygen free radical-induced nitric oxide (NO) breakdown. Since calcium antagonists can improve endothelial function in hypertensive patients, we tested whether this beneficial effect could be related to restoration of NO availability by antioxidant activity. METHODS: In 10 healthy subjects and 20 essential hypertensive patients, we studied forearm blood flow (strain-gauge plethysmography) modifications induced by intrabrachial acetylcholine (from 0.15-15 microg/100 ml per min), bradykinin (0.005-0.05 microg/100 ml per min), two endothelium-dependent vasodilators, and sodium nitroprusside (1-4 microg/100 ml forearm tissue per min), an endothelium independent vasodilator, in the absence and presence of NG-monomethyl-L-arginine (L-NMMA) (100 microg/100 ml forearm tissue per min), an NO synthase inhibitor. RESULTS: In controls, vasodilation to acetylcholine and bradykinin was inhibited by L-NMMA. In hypertensive patients, vasodilation to acetylcholine and bradykinin, but not to sodium nitroprusside, was blunted and resistant to L-NMMA. Hypertensive patients were randomized to a 12-week treatment with lacidipine (4-6 mg/daily) or atenolol (50-100 mg/daily) (n = 10 each group). Lacidipine but not atenolol increased the vasodilation to acetylcholine and bradykinin and restored the inhibiting effect of L-NMMA on endothelium-dependent vasodilation, without affecting the response to sodium nitroprusside. Moreover, lacidipine reduced circulating markers of oxidative stress including plasma and low-density lipoprotein (LDL) hydroperoxides, the susceptibility of LDL to Cu2+-induced oxidation and the reactive oxygen species generated from human umbilical vein endothelial cells after incubation with LDL derived from plasma of the patients. CONCLUSIONS: Lacidipine increases endothelium-dependent vasodilation by restoring NO availability, and this effect possibly is related to antioxidant activity.

Adrenergic beta-Antagonists↗

PubMed2001

Endothelial dysfunction in hypertension.

The endothelium can greatly influence vascular tone and structure. The main endothelium-derived factor is nitric oxide (NO), which is not only a potent vasodilator but also inhibits platelet aggregation, smooth muscle cell proliferation, monocyte adhesion and adhesion molecule expression, thus protecting the vessel wall against the development of atherosclerosis and thrombosis. In human hypertension, endothelial dysfunction has been documented in peripheral and coronary macro- and microcirculation and in renal circulation. The mechanism responsible for endothelial alteration in essential hypertensive patients appears to be the activation of an alternative pathway involving cyclooxygenase, which reduces NO availability through production of oxidative stress. In the presence of impaired NO availability a hyperpolarizing factor seems to act as a compensatory pathway to sustain endothelium-dependent relaxation. This compensatory pathway can be further depressed by the simultaneous presence of essential hypertension and hyperhomocysteinaemia, another cardiovascular risk factor causing endothelial dysfunction. Finally, reduced NO availability can increase the biological activity of endothelin-1 because, while in healthy conditions the vasoconstrictor effect of endothelin-1 is partially blunted by endothelial ETB-receptor mediated NO production, in essential hypertensive patients this protective mechanism is lacking on account of impaired NO availability. This alteration in the NO pathway could be the main mechanism through which a dysfunctional endothelium could be a promoter of atherosclerosis and thrombosis and therefore lead to cardiovascular events in essential hypertensive patients.

Biological Factors↗

PubMed2001

Characterization of adenovirus-induced inverted terminal repeat-independent amplification of integrated adeno-associated virus rep-cap sequences.

Stable packaging cell lines expressing the rep and cap genes for recombinant adeno-associated virus type 2 (rAAV-2) assembly constitute an attractive alternative to transient transfection protocols. We recently characterized a stable HeLa rep-cap cell clone (HeRC32) and demonstrated that upon vector transfection and adenovirus infection, efficient rAAV assembly correlated with a 100-fold amplification of the integrated rep-cap sequence with the inverted terminal repeats (ITRs) deleted. We now report a more detailed analysis of this phenomenon and highlight the key cellular and viral factors involved. Determination of the rep-cap copy number of HeRC32 cells indicated that maximum rep-cap amplification occurred between 24 and 48 h following adenovirus infection. Analysis by pulsed-field gel electrophoresis of adenovirus-infected HeRC32 cells indicated that amplified rep-cap sequences were found in an extrachromosomal form. Amplification of the rep-cap sequence with the ITRs deleted was not dependent on adenovirus replication and still occurred when the highly specific adenovirus polymerase was inactivated. In contrast, amplification was inhibited in the presence of aphidicolin, indicating that cellular polymerases were needed. Our study also documented that among the adenovirus gene products, the DNA-binding protein (DBP) was essential, since rep-cap amplification was severely abrogated when HeRC32 cells were infected at a nonpermissive temperature with an adenovirus mutant encoding a thermosensitive DBP. Furthermore, expression of DBP alone in HeRC32 cells was sufficient to induce a sustained level of rep-cap amplification. Finally, immunofluorescence analysis showed that HeRC32 cells expressing the DBP also simultaneously expressed the Rep proteins, suggesting a possible involvement of the latter in rep-cap amplification. Indeed, the lack of detectable amplification in an adenovirus-infected stable rep-cap HeLa cell clone unable to produce Rep proteins further supported that, among the viral gene products, both the DBP and Rep proteins are necessary to induce the targeted amplification of the integrated rep-cap sequences in the absence of the AAV ITRs.

Adenoviridae↗

PubMed2001

Novel cis-acting replication element in the adeno-associated virus type 2 genome is involved in amplification of integrated rep-cap sequences.

This study identifies a region of the adeno-associated virus type 2 (AAV-2) rep gene (nucleotides 190 to 540 of wild-type AAV-2) as a cis-acting Rep-dependent element able to promote the replication of transiently transfected plasmids. This viral element is also shown to be involved in the amplification of integrated sequences in the presence of adenovirus and Rep proteins.

Base Sequence↗

PubMed2001

Exclusion of the ACE D/I gene polymorphism as a determinant of endothelial dysfunction.

A deletion/insertion (D/I) polymorphism within the ACE gene may increase the risk of cardiovascular events through still unknown mechanisms. The latter may involve increased angiotensin II-induced NO breakdown and/or reduced agonist-mediated NO release. We therefore investigated whether the D allele of the ACE gene affects endothelium-dependent vasodilatation in mild-to-moderate primary hypertensive patients and healthy normotensive subjects. We compared in a cross-sectional study the forearm blood flow response of the 3 D/I genotypes with 5 incrementally increasing doses of the endothelium-dependent vasodilator acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg. 100 mL(-1). min(-1)) in 142 subjects: 103 mild-to-moderate uncomplicated primary hypertensives (49.3+/-9.1 years old, 152+/-11/99+/-5 mm Hg) and 39 normotensives (44.6+/-15.3 years old, 122+/-12/78+/-6 mm Hg). We also assessed the endothelium-independent vasodilatation in the forearm, as blood flow response to 3 incrementally increasing doses of sodium nitroprusside (1, 2, and 4 microg. 100 mL(-1). min(-1)). The overall genotype distribution was II, n=10; ID, n=70; and DD, n=62. It did not differ significantly between primary hypertensives and normotensives. A significant blunting of endothelium-dependent vasodilatation in primary hypertensive patients compared with normotensive subjects (P:<0.001) was found. No effect of the DI genotype on endothelium-dependent and -independent vasodilatation was detected. Thus, these results obtained in a relatively large population do not support the contention that the D allele is associated with a blunting of either stimulated endothelial NO or donated NO responses in both mild-to-moderate primary hypertensive patients and normotensive subjects.

Acetylcholine↗

PubMed2001

Restoration of nitric oxide availability after calcium antagonist treatment in essential hypertension.

Essential hypertension is associated with impaired endothelium-dependent vasodilation caused by oxygen free radical-induced nitric oxide (NO) breakdown. Because calcium antagonists can improve endothelial function in patients with essential hypertension, in this study we tested the hypothesis that this beneficial effect could be related to restoration of NO availability by antioxidant properties. In 15 healthy subjects and 15 hypertensive patients, we studied forearm blood flow (strain-gauge plethysmography) modifications induced by intrabrachial acetylcholine (ACh; 0.15, 0.45, 1.5, 4.5, and 15 microg/100 mL per minute), an endothelium-dependent vasodilator in basal conditions, during infusion of N:(G)-monomethyl-L-arginine (L-NMMA, 100 microg/100 mL forearm tissue per minute), an NO-synthase inhibitor, vitamin C (8 mg/100 mL forearm tissue per minute), and finally, simultaneous infusion of L-NMMA and vitamin C. The response to sodium nitroprusside (SNP; 1, 2, and 4 microg/100 mL forearm tissue per minute) was also evaluated. In control subjects, vasodilation to ACh was inhibited by L-NMMA and not changed by vitamin C. In hypertensive patients, vasodilation to ACh was blunted as compared with control subjects and resistant to L-NMMA. Vitamin C, which decreased plasma isoprostanes and increased plasma antioxidant capacity, increased the response to ACh and restored the inhibiting effect of L-NMMA. In hypertensive patients, the study was repeated after 3-month treatment with nifedipine gastrointestinal therapeutic system (30 to 60 mg/daily). Nifedipine treatment decreased circulating plasma lipoperoxides and isoprostanes and increased plasma antioxidant capacity. Moreover, nifedipine increased the vasodilation to ACh but not to SNP and restored the inhibiting effect of L-NMMA on ACh-induced vasodilation, whereas vitamin C no longer exerted its facilitating activity. These results indicate that nifedipine increases endothelium-dependent vasodilation by restoring NO availability, an effect probably determined by antioxidant activity.

Acetylcholine↗

PubMed2001

Age-related reduction of NO availability and oxidative stress in humans.

Age-related endothelial dysfunction could be caused by an alteration in the L-arginine-NO system and the production of oxidative stress in both normotensive and hypertensive individuals. In 47 normotensive subjects and 49 patients with essential hypertension, we evaluated forearm blood flow (by strain-gauge plethysmography) modifications induced by intrabrachial sodium nitroprusside (1, 2, and 4 microg/100 mL per minute) and acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg/100 mL per minute), an endothelium-independent vasodilator and an endothelium-dependent vasodilator, respectively. Acetylcholine was repeated in the presence of the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 100 microg/100 mL per minute), the antioxidant vitamin C (8 mg/100 mL per minute), or both. Vasodilation to acetylcholine, but not to sodium nitroprusside, was lower (P<0.01) in hypertensive patients compared with control subjects. Moreover, in both groups, endothelium-dependent vasodilation declined with aging. In normotensive subjects, the inhibiting effect of L-NMMA on response to acetylcholine decreased in parallel with advancing age, whereas vitamin C increased vasodilation to acetylcholine in only the oldest group (age >60 years). In young hypertensive patients (age <30 years), vasodilation to acetylcholine was sensitive to L-NMMA, whereas in hypertensive patients age >30 years, vitamin C enhanced endothelium-dependent vasodilation and restored the inhibiting effect of L-NMMA on response to acetylcholine. In normotensive individuals, an earlier primary dysfunction of the NO system and a later production of oxidative stress cause age-related reduction in endothelium-dependent vasodilation. These alterations are similar but anticipated in hypertensive patients compared with normotensive subjects.

Acetylcholine↗

PubMed2000

Physical activity prevents age-related impairment in nitric oxide availability in elderly athletes.

BACKGROUND: Aging is associated with increased cardiovascular risk and endothelial dysfunction. Since exercise can improve endothelium-dependent vasodilation, in the present study we tested whether long-term physical activity could prevent aging-related endothelial dysfunction. METHODS AND RESULTS: In 12 young and elderly (age 26.9+/-2.3 and 62.9+/-5.8 years, respectively) healthy sedentary subjects and 11 young and 14 elderly matched athletes (age 27.5+/-1.9 and 66.4+/-6.1 years, respectively), we studied (with strain-gauge plethysmography) forearm blood flow modifications induced by intrabrachial acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg/100 mL per minute), an endothelium-dependent vasodilator, at baseline, during infusion of N(G)-monomethyl-L-arginine (L-NMMA) (100 microg/100 mL forearm tissue per minute), a nitric oxide-synthase inhibitor, vitamin C (8 mg/100 mL forearm tissue per minute), an antioxidant, and finally under simultaneous infusion of L-NMMA and vitamin C. The response to sodium nitroprusside (1, 2, and 4 microg/100 mL forearm tissue per minute) was also evaluated. In young athletes and sedentary subgroups, vasodilation to acetylcholine was inhibited by L-NMMA and was not changed by vitamin C. In elderly subjects, vasodilation to acetylcholine was blunted as compared with young subjects in both control subjects and athletes, whereas the response to sodium nitroprusside was similar. Moreover, in elderly athletes, vitamin C did not change the vasodilation to acetylcholine. In contrast, in elderly sedentary subjects, the response to acetylcholine was resistant to L-NMMA. In this subgroup, vitamin C increased the vasodilation to acetylcholine and restored the inhibiting effect of L-NMMA. CONCLUSIONS: These results suggest that regular physical activity can at least in part prevent the age-induced endothelial dysfunction, probably the restoration of nitric oxide availability consequent to prevention of production of oxidative stress.

Acetylcholine↗

PubMed2000

Effect of starvation and chlormethiazole on cytochrome P450s of rat nasal mucosa.

Cytochrome P450 (CYP) enzymes of nasal tissue are relatively resistant to induction by classical inducers. In the present study, the effects of starvation on the expression of CYP1A, 2A, 2B, 2C, 2E, 2G, and 3A subfamilies in the nasal mucosa of rat were studied. Fasting for 72 hr caused an increase in 2E1-dependent p-nitrophenol hydroxylase and 1A-dependent ethoxy- (or methoxy) resorufin dealkylase activities, but did not affect either 2A-linked coumarin hydroxylase or the testosterone hydroxylase activity, the latter reaction being a marker of several CYPs including 2G1. Whereas increases in 2E1- and 1A- associated catalytic activities were accompanied by a concomitant increase in the corresponding apoproteins as determined by immunoblotting, immunoactive protein bands reactive with antibodies raised against rat 1A1, 2B1, 2C11, 3A1 or rabbit nasal 2A10/11 and 2G1 were not altered. Fasting also increased CYP2E1 and CYP1A2 on the mRNA level, but did not alter CYP1A1 mRNA as determined by hybridization with cDNA probes selective for these cytochromes. A reiterative administration of chlormethiazole, a specific inhibitor of 2E1 in liver, strongly inhibited many CYPs, including 2E1, 1A2, 2G1, and 2A in the nasal mucosa, but did not influence expression of 2B or 3A as determined by immunoblotting or catalytic activities. The chlormethiazole-mediated inhibition of 1A1 and 2E1 was demonstrated to be at the mRNA level. These results suggest that fasting induces the gene expression of 2E1 and 1A2 and that the mechanisms involved in the regulation of CYPs in the nasal mucosa are tissue-specific. The inducibility of the above-mentioned isoforms may have a significant role in the clearance of drugs and bioactivation of inhaled compounds.

Animals↗

PubMed2000

Mechanisms responsible for endothelial dysfunction associated with acute estrogen deprivation in normotensive women.

BACKGROUND: The goal of this study was to evaluate whether endothelial dysfunction associated with acute estrogen deprivation is caused by an alteration in the L-arginine-nitric oxide (NO) pathway and oxidative stress. Methods and Results-In 26 healthy women (age, 45.7+/-5.4 years) and 18 fertile women with leiomyoma (age, 44.5+/-5.1 years), we studied forearm blood flow (strain-gauge plethysmography) changes induced by intrabrachial acetylcholine (0. 15, 0.45, 1.5, 4.5, or 15 microgram. 100 mL(-1). min(-1)) or sodium nitroprusside (1, 2, or 4 microgram. 100 mL(-1). min(-1)), an endothelium-dependent or -independent vasodilator, respectively. The NO pathway was evaluated by repeating acetylcholine during L-arginine (200 microgram. 100 mL(-1). min(-1); 13 control subjects and 9 patients) or N(G)-monomethyl-L-arginine (L-NMMA; 100 microgram. 100 mL(-1). min(-1); 13 control subjects and 9 patients); production of cyclooxygenase-derived vasoconstrictors was assessed by repeating acetylcholine during indomethacin (50 microgram. 100 mL(-1). min(-1); 13 control subjects and 9 patients) or vitamin C (8 mg. 100 mL(-1). min(-1); 13 control subjects and 9 patients). Patients repeated the study within 1 month after ovariectomy and again after 3 months of estrogen replacement therapy (ERT; 17 beta-estradiol TTS, 50 microgram/d). Basally, vasodilation to acetylcholine was potentiated and inhibited by L-arginine and L-NMMA, respectively (P<0.05), but was unaffected by indomethacin or vitamin C. After ovariectomy, the modulating effect of L-arginine and L-NMMA disappeared, whereas indomethacin and vitamin C potentiated the response to acetylcholine (P<0.05). ERT restored L-arginine and L-NMMA effects on vasodilation to acetylcholine but prevented the potentiation caused by indomethacin or vitamin C. Response to sodium nitroprusside was unaffected by either ovariectomy or ERT. CONCLUSIONS: Endothelial dysfunction secondary to acute endogenous estrogen deprivation is caused by reduced NO availability. Cyclooxygenase-dependent production of oxidative stress could be responsible for this alteration.

Acetylcholine↗

PubMed2000

Improvement of erythropoiesis in beta-thalassemic mice by continuous erythropoietin delivery from muscle.

beta-Thalassemias are highly prevalent genetic disorders that can cause severe hemolytic anemia. The main pathophysiologic feature of beta-thalassemia is the accumulation of unpaired alpha-globin chains in erythrocyte precursors and red blood cells (RBCs). This accumulation alters cell membrane function and results in early cell destruction and ineffective erythropoiesis. Correction of globin chain imbalance through the induction of fetal hemoglobin (HbF) synthesis is a tentative therapeutic approach for this class of diseases. In short-term in vitro or in vivo assays, recombinant human erythropoietin increases the frequency of erythroid precursors programmed to HbF in humans and to beta-minor globin in mice. In contrast, long-term treatment of beta-thalassemic patients did not induce HbF significantly. We took advantage of highly efficient adeno-associated virus-mediated (AAV-mediated) gene transfer into mouse muscle to induce a robust and sustained secretion of mouse erythropoietin in beta-thalassemic mice, which represent a suitable model for human beta-thalassemia intermedia. A 1-year follow-up of 12 treated animals showed a stable correction of anemia associated with improved RBC morphology, increased beta-minor globin synthesis, and decreased amounts of alpha-globin chains bound to erythrocyte membranes. More effective erythropoiesis probably accounted for a reduction of erythroid cell proliferation, as shown by decreased proportions of circulating reticulocytes and by reduced iron 59 ((59)Fe) incorporation into erythroid tissues. This study indicates that the continuous delivery of high amounts of autologous erythropoietin induced a sustained stimulation of beta-minor globin synthesis and a stable improvement of erythropoiesis in the beta-thalassemic mouse model. (Blood. 2000;95:2793-2798)

Animals↗

PubMed2000

Heterogenous effects of anthraquinones on drug-metabolizing enzymes in the liver and small intestine of rat.

The induction of a variety of drug-metabolizing enzymes by six anthraquinones (AQs) has been investigated in the liver and small intestine of rat. In the liver, the intragastric administration for 3 days of 100 mg/kg 9,10-anthraquinone (9,10-AQ). 1-hydroxy-AQ, 1,4-dihydroxy-AQ, but not 1,2-dihydroxy-AQ and 2-carboxy-AQ, resulted in a significant induction of the UDP-GT, DT-diaphorase, P450 1A-linked monooxygenase activities and in particular the methoxyresorufin-O-demethylase (MEROD), an activity dependent on P450 1A2. Immunoblot analysis indicated that 1-hydroxy-AQ and 1,4-dihydroxy-AQ induced P450 1A2 but not 1A1 and 9,10-AQ induced both P4501A2 and P4502B. Northern blotanalysis, using a cDNA probe for CYP 1A1 and CYP 1A2, confirmed that the AQs induce CYP 1A2 but not 1A1 mRNA. In the mucosa of small intestine, none of the above-mentioned enzymatic activities were enhanced following AQ administration. The induction mechanism of the hepatic enzymes by AQs is not known and it deserves a further study as it might be independent from the activation of the Ah-receptor as reported for other tricyclic compounds. The results from inhibition experiments showed that the hydroxylated AQs were strong inhibitors of P450 1A2-dependent monooxygenases. This suggests that long-term ingestion of certain AQs, may affect the toxicity of other components present in the diet through the hepatic induction or inhibition of P450 1A2.

Animals↗

PubMed2000

An MCM2-related gene is expressed in proliferating cells of intact and regenerating planarians.

The minichromosome maintenance (MCM2-7) gene family encodes conserved proteins, which are essential for DNA replication licensing in eukaryotes. They are abundant in proliferating cells, and specific MCM transcripts undergo cell cycle-dependent oscillations. Here we report the characterization of a planarian MCM2 homologue, DjMCM2, which represents the first molecular marker for detecting proliferating cells in planarians. DjMCM2-expressing cells are broadly distributed in the mesenchymal space of the body, with the exception of the cephalic region, and are preferentially accumulated in the peripheral area of the dorso-lateral mesenchyme, along the anteroposterior axis. During regeneration, no DjMCM2 transcripts are observed within the blastema, according to the current view that this structure is not a proliferation site in planarians. Spatio-temporal changes in DjMCM2 RNA expression pattern in the stump parallel blastema growth, coordinately with the orientation of the cut. X-ray irradiation results in the disappearance of DjMCM2 expression, thus confirming that these transcripts are detected specifically in proliferating cells, visualized as neoblasts by in situ hybridization in dissociated cells. In addition to neoblasts, rare large DjMCM2-expressing cells are observed in macerates of tissues excised just below the wound, suggesting that cell types other than neoblasts may be sporadically recruited for proliferation in planarians.

Amino Acid Sequence↗

PubMed2000

Antihypertensive drugs and reversing of endothelial dysfunction in hypertension.

Essential hypertension is associated with impaired endothelium-dependent vasodilation and is caused mainly by production of oxygen free radicals that can destroy nitric oxide (NO), impairing its beneficial and protective effects on the vessel wall. Antihypertensive drugs can improve or restore endothelium-dependent vasodilation depending on their ability to counteract the mechanisms that impair endothelial function. Although treatment with atenolol gives negative results in peripheral subcutaneous and muscle microcirculation, acute nebivolol exerts a modest vasodilating effect in the forearm circulation. Whether this compound can activate NO production in essential hypertensive patients is controversial. Calcium entry blockers, particularly the dihydropyridine-like drugs, can reverse impaired endothelium-dependent vasodilation in different vascular districts, including the subcutaneous, epicardial, and peripheral arteries and forearm circulation. In the forearm circulation, nifedipine and lacidipine can improve endothelial dysfunction by restoring NO availability. Angiotensin-converting enzyme (ACE) inhibitors, however, seem to improve endothelial function in subcutaneous, epicardial, and renal circulation, but are ineffective in potentiating the blunted response to acetylcholine in the forearm of patients with essential hypertension. Finally, recent evidence suggests angiotensin II receptor antagonists can restore endothelium-dependent vasodilation to acetylcholine in subcutaneous, but not in the forearm muscle, microcirculation. However, treatment with an angiotensin II receptor antagonist can improve basal NO release and decrease the vasoconstrictor effect of endogenous endothelin-1.

Adrenergic beta-Antagonists↗

PubMed2000

Hyaluronidase enhances recombinant adeno-associated virus (rAAV)-mediated gene transfer in the rat skeletal muscle.

Skeletal muscle is a privileged target for long-term rAAV-mediated gene transfer in mouse, rat, dog and non-human primates. Intramuscular injections of rAAV encoding human factor IX in hemophilia B patients have been initiated, based on promising results gathered in affected dogs. We found that intramuscular rAAV administration in rats resulted in restricted transduction essentially along the myofibers axis with poor lateral diffusion. This suggested that the transduction rate might be limited by the ability of the virus to reach sites distant from the injection point. We tested whether hyaluronidase, an enzyme which dissociates the extracellular matrix, could enhance vector diffusion when injected in the rat muscle before administration of rAAV encoding either nuclear-localized beta-galactosidase (rAAVCMVnlsLacZ) or the human alpha-1-antitrypsin (rAAVCMVhAAT) under the control of the cytomegalovirus immediate--early promoter (CMV). The results showed that pretreatment of the rat anterior tibialis muscle with hyaluronidase resulted in: (1) a larger diffusion of the virus indicated by an increase in the area containing LacZ-transduced fibers, and (2) a two- to three-fold increase of transduction efficiency measured by the number of LacZ-positive fibers or by the hAAT serum concentration. We also provide evidence that hyaluronidase was well tolerated and was not associated with short- or long-term toxicity evaluated by morphological studies. Finally, in our experimental conditions, hyaluronidase did not promote rAAV dissemination to other organs as assessed by PCR to detect vector sequences. We conclude that pretreatment of skeletal muscle by hyaluronidase, a clinically available reagent, was harmless and resulted in a consistent and significant increase in rAAV diffusion and transduction levels.

Animals↗