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PubMed2002

Early anti-remodeling effect of labetalol in the congestive heart failure model induced by aortic constriction in the guinea pig.

We investigated the effects of the beta1-beta2-alpha1-blocker, labetalol, in the congestive heart failure (CHF) model induced by aortic constriction in the guinea pig. One hundred days after aortic constriction, 52 animals were given either placebo, labetalol 2 mg/kg/d, or labetalol 20 mg/kg/d for 60 days. Eighteen sham-operated animals were used as controls. Investigations were performed at the end of the treatment period. Compared with sham-operated animals, banded animals receiving placebo showed signs of overt CHF with cardiac, systemic and regional (mesenteric and femoral) hemodynamic dysfunction, and pulmonary and hepatic congestion. An increase in whole heart, atria, and left and right ventricle weights associated with left ventricular cavity enlargement and left and right ventricular wall thickening indicated a remodeling process. Compared with placebo, labetalol did not significantly modify cardiac, systemic, or regional hemodynamic variables but significantly decreased pulmonary and hepatic congestion. Labetalol significantly reduced left ventricular cavity area (-10 and -20% after 2 and 20 mg/kg, respectively) and left ventricular (-4 and -16%) and right ventricular (-4 and -19%) wall thickness. In conclusion, labetalol induced partial regression of cardiac remodeling before hemodynamic improvement. This early anti-remodeling effect could play a role in the favorable effects observed with beta1-beta2-alpha1-blockers in humans.

Adrenergic beta-Antagonists↗
PubMed1990

Persistent arteriolar constriction in microcirculation of the terminal ileum following moderate hemorrhagic hypovolemia and volume restoration.

A stable in vivo preparation of moderate hypovolemia with prompt volume restoration was produced in anesthetized rats. The microcirculation of the terminal ileum was observed in vivo videomicroscopy, and changes in mean arterial pressure (MAP) as well as arteriolar diameters were recorded after a 30-min period in which the MAP was reduced by 50% by bleeding. Volume was restored with shed blood alone (control); dextran 70 alone (dextran); or dextran + hypertonic (7.5%) saline (dextran + HS). A final group of rats was pretreated with allopurinol 5 mg/kg and then treated identically to the control group to assess the role of the xanthine oxidase system in microcirculation changes following hemorrhage. MAP was restored to normal by return of shed blood in control animals, but inflow arterioles (A1) remained significantly constricted. MAP was significantly higher and A1 arteriolar dilation was observed in the dextran + HS group. Responses in allopurinol-pretreated animals were not different from the responses seen in control animals. We conclude that persistent arteriolar constriction is produced by moderate hypovolemia and this effect is ameliorated by volume restoration with dextran + HS.

Allopurinol↗
PubMed1992

Congenital skin tube pedicle associated with the constriction band syndrome.

A very rare case of congenital skin tube pedicle with congenital constriction band syndrome was presented. Only one report concerning this bizarre abnormality could be found in the available literature, and no consideration of its etiology has previously been published. In our case, the skin tube was accompanied by the congenital constriction band syndrome, the cause of which is generally thought to be external factors. Thus the etiology of the congenital skin tube pedicle might be the peeling and rolling of a strip of the fetal skin by external force.

Abnormalities, Multiple↗
PubMed1993

A method of treatment of constricted ears with a conchal cartilage graft to the posterior auricular plane.

In order to make natural auricular features in a simple and certain way and also to prevent the occurrence of a postoperative lop-eared deformity, we contrived a new method to treat constricted ears. Our method consists of correction of the anthelical deformity according to a modified Converse method and a cartilage graft harvested from the posterior region of the concha to fix as a support on the posterior auricular plane which enables the auricle to maintain a normal shape. This method resulted in very satisfactory treatment of prominent ears or ears with mild helical constriction, categorized as group I, IIa, or IIb on Tanzer's classification, and the patients did not have marked postoperative problems. Thus, in this respect, our technique is considered to be a very effective and safe method.

Cartilage↗
PubMed2004

Effects of bunazosin hydrochloride on ciliary muscle constriction and matrix metalloproteinase activities.

PURPOSE: To clarify the mechanism by which bunazosin hydrochloride (BZ), a selective alpha1-adrenoceptor antagonist, increases uveoscleral outflow. METHODS: The effects of BZ on matrix metalloproteinase (MMP) activities in cultured monkey ciliary muscle cells, and on phenylephrine hydrochloride-induced constriction in bovine ciliary muscles, were examined. Also, the possible additive ocular hypotensive effects of BZ and latanoprost (LP) were evaluated in ocular normotensive monkeys. RESULTS: Although BZ at 10 to 10 M did not increase MMP-2, -3, and -9 activities in the culture medium of ciliary muscle cells, BZ at 10 to 10 M inhibited phenylephrine hydrochloride-induced constriction in ciliary muscles. The maximal reduction in intraocular pressure of concomitant administration of BZ and LP was greater than that of BZ alone and tended to be greater than that of LP alone. CONCLUSION: These findings, in normotensive monkeys, indicate that the mechanism whereby BZ increases uveoscleral outflow is independent of an effect on MMPs and is partly due to relaxation of the ciliary muscle. This effect is different from that of LP, which might help to explain the finding that topical concomitant administration of BZ and LP increased AUC(0-6h) value (IOP reduction) to 201% and 145% of BZ and LP given alone, respectively.

Adrenergic alpha-Antagonists↗
PubMed2006

Effects of Hct on L-NAME-induced potentiation of anaphylactic presinusoidal constriction in perfused rat livers.

Effects of hematocrit (Hct) on N-nitro-L-arginine methyl ester (L-NAME)-induced modulation of anaphylactic venoconstriction were determined in isolated perfused rat livers. The rats were sensitized with ovalbumin (1 mg), and the livers were excised 2 weeks later and perfused portally and recirculatingly under constant flow at Hct of 0%, 5%, 16%, and 22%. The hepatic sinusoidal pressure was estimated via the double occlusion pressure (Pdo), and the presinusoidal resistance (Rpre) and the postsinusoidal resistance (Rhv) were calculated. The antigen of ovalbumin 0.1 mg was injected into the reservoir at 10 minutes after pretreatment with L-NAME (100 microM) or D-NAME (100 microM). Perfusate viscosity, a determinant of vascular resistance and shear stress, was increased in parallel with Hct. In the D-NAME groups, antigen caused predominant presinusoidal constriction. The magnitude of venoconstriction was significantly smaller at Hct 0% than at Hct 5% to 22%, whereas no significant differences were found among Hct 5% to 22%. L-NAME potentiated the antigen-induced increase in Rpre, but not in Rpost at Hct 5% to 22% as compared with D-NAME. But the augmentative effects of L-NAME were similar in magnitude among Hct 5% to 22%. These findings suggest that hepatic anaphylaxis increases production of nitric oxide, which consequently attenuates anaphylactic presinusoidal constriction in rat livers, and that these effects are independent of perfusate Hct or viscosity in blood-perfused rat livers.

Anaphylaxis↗
PubMed2006

Blood pressure is the major driving force for plaque formation in aortic-constricted ApoE-/- mice.

OBJECTIVE: Using an aortic constriction model in mice, we studied whether the increase in pressure or the activation of the renin-angiotensin system (RAS) and its main receptors is the main driving force for plaque progression. METHODS: Male ApoE mice underwent sham surgery or placement of a suprarenal silver clip around the aorta (AoC). Half the group was treated with the selective AT1 receptor antagonist losartan (30 mg/kg per day) for 4 weeks. RESULTS: Anesthetized mean arterial pressure (MAP) was increased in AoC mice compared to sham (106 +/- 3 versus 90 +/- 1 mmHg, P < 0.001). Losartan reduced MAP in sham mice (78 +/- 2 mmHg, P < 0.01) but not in AoC (AoC losartan 104 +/- 2 mmHg). Plasma renin concentration (PRC) was increased in AoC mice compared to sham [1.6 +/- 0.3 versus 0.8 +/- 0.2 milliGoldblatt units (mGU)/ml, P < 0.001]. Losartan treatment augmented this difference (18.7 +/- 3.7 versus 4.6 +/- 1.7 mGU/ml, P < 0.01). AT2 receptor mRNA expression was increased 5.8-fold by aortic constriction in thoracic aorta (P < 0.05) and the major site for expression of the AT2 receptor protein was within the plaques. The plaque area was increased in AoC mice compared to sham (0.61 +/- 0.09 versus 0.07 +/- 0.01%, P < 0.001); however, losartan did not alter plaque area. CONCLUSIONS: Our data do not support a role for the AT1 receptor in the progression of atherosclerosis in this model, since blockade with losartan did not alter plaque distribution. Furthermore, we found no support for the counteraction of atherogenesis by increased activity of the RAS acting on the AT2 receptor. Our data suggest that increased pressure is the main driving force for atherosclerosis in this model.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2004

Double pennant technique: elongating the helix using rim flaps to correct the constricted ear.

In a Tanzer group 2B or group 3 constricted ear, the short helix must be elongated with additional tissues. To do this, we have developed a new method of surgical repair using 2 pennant-shaped rim flaps. Six constricted ear patients underwent correctional ear plasty using this method. Four of the deformities were Tanzer group 2b and 2 were group 3. Our surgical procedure elongated the patients' helix from 7 to 22 mm, leaving them with smooth curvature and a good color match to the adjoining skin.

Adult↗
PubMed2006

Threatened lower extremity in a neonate from a severely constricting amniotic band: a case for limb salvage after a 6-year functional follow-up.

A child presented at birth with a threatened lower limb from severe constriction band. Limb salvage was performed by emergency z-plasty reconstructions and subsequent sural nerve grafting to a fibrotic segmental deficit in the sciatic nerve. Follow-up over a 6-year period enables us to provide a favorable outlook with regard to functional use of the extremity and absence of chronic lymphedema, but she does have a significant limb length discrepancy. There is virtually no information on long-term functional outcome of such cases, although textbook teaching advises one to attempt emergency salvage of an extremity that is threatened by a severely constricting congenital amniotic band. Follow-up of our patient equips us with outcome information so that we can now better inform parents when once again faced with this problem in the neonate.

Amniotic Band Syndrome↗
PubMedDate not supplied

Clubfeet associated with congenital constriction bands of the ipsilateral lower extremity.

The purpose of this study was to examine the outcome of treatment of clubfeet distal to a lower extremity constriction band. Eighteen patients with 21 clubfeet distal to a lower extremity constriction band were treated during the years 1946 to 1992. Three types of bands (I to III) were defined. Three grades of feet (A to C), based on the severity of the deformity, were recognized. After treatment, the feet were classified as good, fair, or poor. At follow-up, six of 18 feet were classified as good, six as fair, and nine as poor. These results were correlated with the type of band and the grade of the foot. A grade A foot associated with type III band had the best result.

Amniotic Band Syndrome↗
PubMed2001

Topological investigations of the FomA porin from Fusobacterium nucleatum and identification of the constriction loop L6.

Porin FomA in the outer membrane of Fusobacterium nucleatum is a trimeric protein, which exhibits permeability properties similar to that of the well-known enterobacterial diffusion porins. The proposed topology model of the FomA monomer depicts the beta-barrel motif typical of diffusion porins, consisting of 16 antiparallel beta-strands. To investigate the accuracy of the FomA model and assess the topological relationship with other porins, individual deletions of variable size in seven of the eight surface-exposed regions of the porin were genetically engineered. Deletions in the predicted loops L1 to L7 were tolerated by the FomA porins, as judged by a normal assembly in the outer membrane of Escherichia coli and a sustained pore-forming ability. Deletions in the largest proposed external region, loop L6, made the FomA porins considerably more permeable to antibiotics, indicating larger pore channels. The distinctly increased uptake rates and size exclusion limits displayed by the L6 deletion mutant porins, suggest that loop L6 folds back into the beta-barrel thereby constricting the native FomA channel. Thus, the position of the channel constriction loop appears to be shifted towards the C terminus in the FomA porin, as compared to the crystal structures of five non-specific diffusion porins.

Amino Acid Sequence↗
PubMed2004

Interedge strong-to-weak scattering evolution at a constriction in the fractional quantum Hall regime.

Gate-voltage control of interedge tunneling at a split-gate constriction in the fractional quantum Hall regime is reported. Quantitative agreement with the behavior predicted for out-of-equilibrium quasiparticle transport between chiral Luttinger liquids is shown at low temperatures at specific values of the backscattering strength. When the latter is lowered by changing the gate voltage, the zero-bias peak of the tunneling conductance evolves into a minimum, and a nonlinear quasiholelike characteristic emerges. Our analysis emphasizes the role of the local filling factor in the split-gate constriction region.

Journal Article↗
PubMed1983

Reduction of the veno-arteriolar reflex induced arteriolar constriction in forearm subcutaneous tissue after surgical repair of aortic coarctation.

Arteriolar constriction in subcutaneous tissue elicited by the local sympathetic veno-arteriolar axon reflex was studied in subcutaneous tissue of forearm and leg in 4 patients before and after correction of aortic coarctation. Before the operation the local axon reflex induced an average increase of 154% in vascular resistance in the "hypertensive" forearm and of 76% in the leg. Following coarctectomy the local axon reflex induced increase in vascular resistance decreased in the forearm within 6 months in all patients. Now average increase in vascular resistance was only 109% 3 months after the operation and 45% 6 months after. Minimal vascular resistance in the papaverine relaxed vascular bed was reduced, whereas no systemic changes were seen in the distensibility of the vascular bed. The results indicate that adaptive vascular changes underlying the augmented arteriolar constriction during lowering as well as the increased "minimal vascular resistance" in the forearm are at least partly reversible following coarctectomy.

Adolescent↗
PubMed1987

Airway constriction by isocapnic hyperventilation of cold, dry air: comparison of magnitude and duration of protection by nedocromil sodium and sodium cromoglycate.

The protective effect of 1, 2 and 4 mg of nedocromil sodium against airway constriction induced by hyperventilation of cold, dry air was compared with 10 mg sodium cromoglycate and placebo in a double-blind randomized trial. On 5 days, twelve asthmatic subjects received one of the trial medications from a metered dose inhaler. Twenty minutes, 2.5 and 5 hr later, airway responsiveness to hyperventilation of cold, dry air was measured. At 20 min, there was significant protection by all four active medications when compared to placebo, with a trend towards a nedocromil dose relationship but there was no statistical difference between the four active medications. All four showed a similar progressive decrease in protection over 5 hr. The results of this study suggest that nedocromil gives protection against hyperventilation-stimulated airway constriction and that the magnitude and duration of effect for all three doses is similar to 10 mg of cromoglycate.

Air↗
PubMed2004

Alternative substrates for wild-type and L109A E. coli CTP synthases: kinetic evidence for a constricted ammonia tunnel.

Cytidine 5'-triphosphate (CTP) synthase catalyses the ATP-dependent formation of CTP from uridine 5'-triphosphate using either NH(3) or l-glutamine as the nitrogen source. The hydrolysis of glutamine is catalysed in the C-terminal glutamine amide transfer domain and the nascent NH(3) that is generated is transferred via an NH(3) tunnel [Endrizzi, J.A., Kim, H., Anderson, P.M. & Baldwin, E.P. (2004) Biochemistry43, 6447-6463] to the active site of the N-terminal synthase domain where the amination reaction occurs. Replacement of Leu109 by alanine in Escherichia coli CTP synthase causes an uncoupling of glutamine hydrolysis and glutamine-dependent CTP formation [Iyengar, A. & Bearne, S.L. (2003) Biochem. J.369, 497-507]. To test our hypothesis that L109A CTP synthase has a constricted or a leaky NH(3) tunnel, we examined the ability of wild-type and L109A CTP synthases to utilize NH(3), NH(2)OH, and NH(2)NH(2) as exogenous substrates, and as nascent substrates generated via the hydrolysis of glutamine, gamma-glutamyl hydroxamate, and gamma-glutamyl hydrazide, respectively. We show that the uncoupling of the hydrolysis of gamma-glutamyl hydroxamate and nascent NH(2)OH production from N(4)-hydroxy-CTP formation is more pronounced with the L109A enzyme, relative to the wild-type CTP synthase. These results suggest that the NH(3) tunnel of L109A, in the presence of bound allosteric effector guanosine 5'-triphosphate, is not leaky but contains a constriction that discriminates between NH(3) and NH(2)OH on the basis of size.

Ammonia↗
PubMedDate not supplied

Plasma renin concentration in hypertension produced by unilateral renal artery constriction in the rat.

1. Plasma renin concentration (PRC) and blood pressure were studied sequentially, 24 h to 42 days post-operatively, in rats subjected to unilateral renal artery constriction without contralateral nephrectomy. 2. The PRC of rats failing to develop hypertension remained normal, whereas the mean PRC of twenty-two rats that became hypertensive was five times normal on day 14 of the study when the hypertension was becoming established. 3. In eleven of the twenty-two rats that became hypertensive, PRC did not exceed the upper limit of normal. In the remaining hypertensive rats, the increase in PRC was not always temporally related to the increase in blood pressure. A significant correlation between PRC and blood pressure did not emerge until day 35 of the study. 4. Despite these anomalies, linear regression analysis of 169 pairs of PRC and blood pressure measurements during the 42 day period of development of hypertension in twenty-two rats revealed a highly significant correlation between log PRC and blood pressure (P smaller than 0.001). 5. It is concluded that factors other than the plasma concentration of renin are involved in the early stages of development of hypertension induced by renal artery constriction. Nevertheless, PRC and blood pressure are intricately related.

Animals↗
PubMedDate not supplied

Role of the renin-angiotensin system in hypertension produced by unilateral renal artery constriction in the rat.

1. Conscious rats which had undergone unilateral renal artery constriction were infused for 1 h with a specific antagonist of angiotensin II, 1-Sar-8-Ala-angiotensin II (P-113). 2. There was a highly significant correlation between the change in blood pressure induced by P-113 and the pre-infusion plasma renin concentration (PRC), regardless of initial blood pressure or the duration of stenosis. However, the blood pressure fall was not significantly greater in nineteen hypertensive rats than in eleven which remained normotensive. P-113 did not abolish the hypertension. 3. The extent to which angiotensin II supports blood pressure in rats with renal artery constriction is directly related to the PRC.

Angiotensin II↗
PubMed1996

N-nitro-L-arginine and indomethacin do not affect endothelin-induced constriction of large and small coronary arteries in the anaesthetized greyhound.

1. The aim of this study was to investigate whether endothelin-1 (ET-1)-induced constriction of large and small coronary arteries in the anaesthetized greyhound is modulated by the endogenous release of nitric oxide or prostanoids. 2. ET-1 (1-100 ng/kg) and the alpha1-adrenoceptor agonist phenylephrine (0.5-2 mu g/kg), when injected directly into the circumflex coronary artery, caused dose-dependent decreases in epicardial coronary artery diameter and coronary vascular conductance without affecting systemic arterial pressure or the rate and force of cardiac contraction. 3. Inhibition of NO synthesis with N-nitro-L-arginine (NOLA, 5 mg/kg, i.c.) decreased coronary artery diameter, coronary conductance and heart rate and increased arterial pressure. The coronary vasoconstrictor response to ET-1 was unaffected by NOLA. By contrast, NOLA significantly increased the phenylephrine-induced constriction of the epicardial coronary artery but not the resistance vessels. 4. Indomethacin (5 mg/kg, i.v.), an inhibitor of cyclo-oxygenase, significantly decreased epicardial coronary artery diameter but did not affect coronary conductance. Indomethacin had no effect on the coronary vascular responses to ET-1 or phenylephrine. Combined treatment with NOLA plus indomethacin also failed to affect the coronary vasoconstrictor effects of ET-1. 5. Basal release of NO and vasodilator prostanoids modulated resting coronary vascular tone but did not influence the vasoconstrictor responses to endothelin in either large or small coronary arteries.

Animals↗