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PubMed1983

Recovery of distal changes after nerve constriction by a ligature.

When ligatures were used to constrict the proximal tibial nerve in rabbits, nerve fibres distal to the site of constriction underwent a reduction in axonal and external fibre diameter, and in conduction velocity. Distal changes could be detected within 7-12 days of the onset of constriction; removal of the ligatures was followed by partial recovery. When paranodal myelin damage occurred in the distal tibial nerve, it showed the typical non-random distribution of secondary demyelination, with multiple paranodal defects on some fibres and complete sparing of others. These findings emphasize the role of the axon in the genesis of paranodal demyelination.

Animals↗
PubMed1991

Nonionizing method of locating the apical constriction (minor foramen) in root canals.

The electronic method was evaluated as to its accuracy when used to determine the position of the apical constriction (minor foramen) in root canals. There were 39 vital and 8 nonvital teeth for a total of 47 specimens from 22 patients. The specimens were prepared with a Buehler Isomet bone saw to a thickness of 500 microns. Distances were measured and recorded with the use of a Bioquant II image analysis system. The electronic method appeared to measure a mean value of 0.2 mm coronal to the cemetodentinal junction in 47 canals where the apex locator was set at a reference setting of 40. When a frequency curve was plotted, it showed that the probability of being within 0.76 mm (1 SD) of the cementodentinal junction was 68%. This appears to correlate to where Kuttler indicated the minor constriction to be located. These devices seem to offer a unique method to locate the apical constriction and thus to ensure proper working length while reducing ionizing radiation.

Aged↗
PubMed1996

Cisternal talc injection in dog can induce delayed and prolonged arterial constriction resembling cerebral vasospasm morphologically and pharmacologically.

BACKGROUND: The possible role of inflammation in the pathogenesis of cerebral vasospasm has been noted in recent studies. In order to examine the role of inflammation, we examined the vasocontractile activity of talc, which is known to cause severe inflammation, using a canine cisternal talc injection model. METHODS: Under general anesthesia, a sterile talc powder suspended in saline was injected into the cisterna magna of the dog. Serial vertebral angiography and postmortem histologic changes of the harvested basilar artery were examined. The morphologic and pharmacologic features of talc-induced vessel spasm were compared with the usual autologous blood-induced artery spasm. RESULTS: Cisternal injection of sterile talc powder caused no early spasm, but induced definite basilar arterial constriction 2 days after injection. This vascular constriction was observed to continue up to 7 days after injection. Ultrastructural study of the constricted vessel revealed several morphologic changes, such as corrugation of the elastic lamina, subintimal proliferation, migration of smooth muscle cells, detachment of endothelial cells, etc.; findings that are compatible with the changes observed in vasospasm. Pharmacologic study showed a moderate decrease in the maximal contraction to KCl and UTP. Endothelium-dependent relaxation was markedly disturbed, while endothelium-independent relaxation was preserved. These pharmacologic properties were also similar to those reported in vasospasm. CONCLUSIONS: Our present study indicates that the several changes of vascular properties, which had been considered to be specific to cerebral vasospasm, can be regarded as a nonspecific biologic defense reaction against the foreign body. The analysis of the common pathway from talc and autologous blood to vasospasm may lead to the pathogenesis of cerebral vasospasm.

Animals↗
PubMed1979

Potent constriction of cat coronary arteries by hydroperoxides of arachidonic acid and its blockade by anti-inflammatory agents.

The omega-6 and omega-9 hydroperoxides of arachidonic acid caused dose-dependent constriction of cat coronary arteries in concentrations of 10(-8) to 10(-5) M. Their potency was comparable to that of prostaglandin (PG) E2, and PGF2 alpha and 100 times greater than that of arachidonic acid. The cyclooxygenase inhibitor, meclofenamate markedly reduced constriction caused by the hydroperoxides but potentiated constriction caused by the prostaglandins. The effects of the hydroperoxides were also reduced by indomethacin and dexamethasone but were unaffected by the thromboxane synthetase inhibitor imidazole. Since the hydroperoxides are not substrates for cyclooxygenase, it is suggested that they have a direct effect on the arteries which can be antagonized by anti-inflammatory drugs.

Animals↗
PubMed1984

Constriction of fetal ductus arteriosus by non-steroidal anti-inflammatory drugs:study of additional 34 drugs.

Our study on transplacental effects of 24 non-steroidal anti-inflammatory drugs (NSAID) on the fetal ductus arteriosus of full-term pregnant rats was extended to 34 other NSAID using the same whole-body freezing technique (1). In total, 58 NSAID were evaluated, and their potency in usual clinical doses was classified into 4 grades. Indomethacin and 15 other NSAID caused strong fetal ductal constriction, phenylbutazone and 14 other NSAID caused moderate, and aspirin and 16 other NSAID caused mild constriction of the fetal ductus arteriosus. Salicylamides, and six out of eight basic NSAID did not constrict the fetal ductus arteriosus. Further clinical implications of these results are discussed.

Animals↗
PubMed1983

Adrenalectomy potentiates drinking induced by renal artery constriction.

We have tested the hypothesis that the dipsogenic response to an increase in the circulating angiotensin level in the rat is mediated via release of catecholamines from the adrenal medulla. Increases in circulating angiotensin levels were induced by unilateral renal artery constriction in animals which were uninephrectomized and/or adrenalectomized, twenty four hours previously. The dipsogenic response to renal artery constriction was not attenuated by prior adrenalectomy--there was, in fact, a slight potentiation. Adrenalectomy also potentiated the dipsogenic response to injection of hypersomotic saline. We conclude that drinking following renal artery constriction is not mediated by release of catecholamines from the adrenal medulla.

Adrenal Medulla↗
PubMed1979

A double constriction micropipette for the quantitative injection of tracer substance.

A glass, double constriction injector micropipette ('micropet') has been designed to overcome problems associated with commercial microliter syringes. These problems include: inconsistent volume delivery, inability to view tracer during filling or injection, and the relatively large size of the needle supplied. 'Micropets' of different volumes are easily made from inexpensive, commercially available Drummond 100 microliter glass tubes (bores) fitted with teflon plungers. Tracer substances may be viewed in the bores during filling and injection and the needle tip can be pulled as small as 50 micrometers. For deep stereotactic injection, a long triple constriction 'micropet' has also been devised. The 'micropet' is based in principle on the commercial Lang-Levy double constriction micropipettes and these are used for radiometric calibration of the 'micropets'. Thus the 'micropet' accuracy is a reflection of these commercial micropipettes, and is approximately +/- 0.5%. Precision is also on the order of +/- 0.5% as determined by radioassay. When combined with an oil-filled, variable-speed microdrive the injector 'micropet' provides a highly controlled and precise system for the accurate delivery of tracer substance important for quantitative neuroanatomical investigations.

Animals↗
PubMed1991

Effects of sodium pentothal and sufentanil on serotonin induced constriction of canine coronary artery rings without endothelium.

1. The individual and combined effects of sufentanil and sodium pentothal on canine coronary artery vasomotor responses to 5-HT were studied in an isolated vascular ring preparation. 2. Clinical concentrations of sufentanil have little effect on basal coronary tension or constriction induced by either 5-HT or sodium pentothal individually, until very high doses greater than 0.26 microM are reached. 3. Sodium pentothal causes coronary constriction at clinical concentrations and this effect is additive and possibly potentiated when combined with 5-HT. 4. Sufentanil inhibits coronary constriction induced by the combination of sodium pentothal and 5-HT.

Anesthetics↗
PubMed1991

Doppler echocardiography of fetal ductus arteriosus constriction versus increased right ventricular output.

A prospective longitudinal study from 121 examinations of 41 normal pregnant women showed that fetal ductal flow velocities increased with gestational age. These normal data were compared with data in three groups of fetuses with altered ductal flow velocities: 22 fetuses (mean gestational age 31.3 weeks) had ductal constriction due to maternal indomethacin treatment; 10 fetuses (mean gestational age 27.9 weeks) had been exposed to terbutaline, a positive inotropic agent and 14 fetuses (mean gestational age 33.3 weeks) had hypoplastic left heart syndrome. In normal fetuses maximal systolic, mean and end-diastolic ductal flow velocities increased linearly (p less than 0.0001). The pulsatility index did not change (mean +/- 2 SD: 2.46 +/- 0.52). Fetuses with ductal constriction had higher maximal, mean and end-diastolic flow velocities and a significantly lower pulsatility index than did normal fetuses (1.25 +/- 0.76; p less than 0.0005). Six of 10 fetuses of the terbutaline group and 8 of 14 fetuses with hypoplastic left heart syndrome had increased maximal flow velocity, but normal or only mildly elevated mean flow velocity. The pulsatility index in fetuses during terbutaline therapy and with hypoplastic left heart syndrome was significantly higher than in normal fetuses (3.11 +/- 0.46 and 3.09 +/- 0.7, respectively, vs. 2.46 +/- 0.52; p less than 0.0005). Fetal ductal waveform analysis was necessary to distinguish fetal ductal constriction from increased right ventricular output. These measurements may be helpful in the diagnosis of left-sided outflow obstruction and assessment of fetal hemodynamic data.

Blood Flow Velocity↗
PubMed2004

Comparison of effects of cyclooxygenase inhibitors on myometrial contraction and constriction of ductus arteriosus in rats.

The aim of this study was to compare the tocolytic effect of a selective cyclooxygenase-2 inhibitor, DFU (5,5-dimethyl-3(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furanone), indomethacin and nimesulide on myometrial strips isolated from rats in both lipopolysaccharide-induced preterm labour and term labour. We also compared the constrictor effects of DFU and indomethacin on the fetal ductus arteriosus. Myometrial strips were obtained from preterm and term labour Wistar albino rats and were mounted in organ baths for the recording of isometric tension. DFU, nimesulide and indomethacin significantly inhibited KCl-, oxytocin-, prostaglandin E(2)- and prostaglandin F(2 alpha)-stimulated contractions of myometrial strips isolated from rats in preterm and term labour. The E(max) value of indomethacin was significantly lower than those for DFU and nimesulide (P<0.05), with no change-log (10) EC(50) values. There was no significant difference between in -log (10) EC(50) and E(max) values of DFU and nimesulide for any of the tissues (P>0.05). In addition, there was no significant difference between -log (10) EC(50) and E(max) values for each of these three agents in myometrial tissues isolated from rats in preterm and term labour (P>0.05). Fetal ductus arteriosus was significantly constricted by DFU (10 or 100 mg/kg) in preterm and term rats, although DFU (10 or 100 mg/kg)-induced constriction ratios were significantly lower than those for indomethacin (P<0.05). These data demonstrate that DFU, a specific cyclooxygenase-2 inhibitor, could be considered as a new therapeutic agent for preterm labour. However, careful attention should be given to constriction of the fetal ductus arteriosus.

Animals↗
PubMed2006

Mediators of CD18/P-selectin-dependent constriction of venule-paired arterioles in hypercholesterolemia.

This study addresses the role of venule-derived mediators in the arteriolar constriction that accompanies hypercholesterolemia. Constriction was assessed by measuring the tone of small arterioles closely paired with venules in the mesentery of normal cholesterol rats (NC), high cholesterol rats (HC), HC rats injected with antibodies against CD18 and P-selectin (HC/mAbs), HC rats treated with the thromboxane synthase inhibitor, ozagrel (HC/ozagrel), and HC rats pretreated with anti-platelet serum (HC/APS). Venule-paired arterioles in the untreated HC group demonstrated enhanced tone compared with arterioles in the NC group, while no difference was found between unpaired arterioles of the two groups. Perivascular nitric oxide (NO) concentrations were found to be significantly decreased in venule-paired arterioles of HC rats (238+/-14 nM) compared with those of NC rats (426+/-42 nM). The injection of anti-adhesion antibodies successfully attenuated the enhanced arteriolar tone and venular leukocyte adherence in the HC group, and tended to increase levels of NO in venule-paired arterioles by 33% (to 326+/-19 nM; still lower than that of the NC group). Ozagrel and platelet depletion attenuated the enhanced arteriolar tone by 53% and 33%, respectively, without affecting NO concentrations. These findings indicate that the mechanism of blood cell-dependent arteriolar constriction during hypercholesterolemia may be dependent on thromboxane, a decrease in NO, and the proximity of the arterioles to postcapillary venules.

Animals↗
PubMed2005

Improvement of refractory rheumatoid arthritis-associated constrictive bronchiolitis with etanercept.

Rheumatoid arthritis (RA)-associated constrictive bronchiolitis is a severe condition with no established efficient treatment. A 55-year-old woman with seropositive RA developed rapidly progressive constrictive bronchiolitis confirmed by lung biopsy. Her clinical condition worsened despite steroids and azathioprine. Treatment with etanercept-a tumor necrosis factor (TNF)-alpha inhibitor-combined with methotrexate, resulted in a marked improvement of both her clinical condition and pulmonary function tests. Treatment with TNF-alpha inhibitors and methotrexate may be proposed in RA-associated constrictive bronchiolitis, a severe condition hitherto not amenable to improvement.

Antirheumatic Agents↗
PubMed1988

Postoperative fibrous cardiac constriction.

Two patients with postoperative fibrous cardiac constriction are described. Unlike postoperative pericardial or epicardial constriction, the fibrous constricting layer in these patients envelopes the vein bypass grafts and is separate from the pericardium, which is not involved. Surgical management of these patients is difficult and hazardous; a strategy is outlined.

Cardiomyopathies↗
PubMed2002

Behavioral and electrophysiological consequences of deafferentation following chronic constriction of the infraorbital nerve in adult rats.

Deafferentation of the hind paw following sciatic nerve injury results in behavioral changes, such as autotomy, suggestive of persistent, spontaneous pain. The effects of deafferentation involving trigeminal nerves have, however, received less attention. Here, alterations in trigeminal ganglion neuronal activity and mechanically evoked and spontaneous behavior were studied in adult rats after a chronic constriction injury of the infraorbital nerve (ION). Compared to sham-operated rats, most rats with ION damage were unresponsive to mechanical stimulation of the mystacial vibrissae up to 56 days after surgery. Increased facial grooming was observed only in rats with chronic ION constriction 10 days after surgery. Free-ranging behavior was similar to that of sham-injury animals. In contrast, increases in the number of spontaneously active trigeminal ganglion neurones were observed in those rats with ION injuries at both 3 and 56 days. These data suggest that chronic constrictive injuries of the ION resulting in prolonged loss of low-threshold input from the periphery lead to only transient behavioral changes, despite the presence of spontaneous activity in trigeminal sensory neurones.

Afferent Pathways↗
PubMed2001

A beta-fiber intensity stimulation of chronically constricted median nerve induces c-fos expression in thalamic projection neurons of the cuneate nucleus in rats with behavioral signs of neuropathic pain.

This study was aimed to investigate the possible involvement of neurons in the cuneate nucleus (CN) in the processing of A beta afferent inputs evoked by electrical stimulation of constricted median nerve in rats with behavioral signs of neuropathic pain. Immunohistochemical localization of Fos protein was used to examine the neuronal activation, and the combination of Fos immunohistochemistry with the retrograde labeling of Fluoro-Gold (FG) injected into the ventrobasal complex of the thalamus was used to characterize the activated neurons. Two weeks after unilateral median nerve constriction injury, the rats exhibited behavioral signs of neuropathic pain in the affected forepaws. In rats after nerve injury but without electrical stimulation, some Fos-like immunoreactive (Fos-LI) neurons were detected in the dorsal horn of the seventh cervical segment (C7) but none was found in the CN. Similar features were also noted when the stimulation of the intact median nerve served as an additional control. After A beta-fiber intensity stimulation of the previously constricted median nerve, an increase in number of Fos-LI neurons occurred in the medial half of the ipsilateral C7 dorsal horn as well as in the ipsilateral CN. In the latter, the Fos-LI neurons were located in the median nerve projection territory throughout the nucleus. Most of the Fos-LI neurons were distributed in the middle region of the CN, with about 78% of them emitting FG fluorescence indicating that they were cuneothalamic projection neurons. The results of this study suggest that the dorsal column-medial lemniscal system may contribute to the transmission and modulation of A beta-fiber mediated neuropathic pain signals.

Animals↗
PubMed2002

Changes in brain Na, K-ATPase isoform expression and enzymatic activity after aortic constriction.

The objective of the present study was to test the hypothesis that brain Na, K-ATPase expression and/or activity is altered following an increase in blood pressure produced by constriction of the abdominal aorta just proximal to the renal arteries. A suprarenal constriction (SRC) was made to conform to the diameter of a 19-gauge (19-G) or 20-gauge (20-G) needle, while in a sham-operated group (Sham) the aorta was exposed surgically but not constricted. Within 1 week of SRC, mean arterial pressure was increased and remained elevated at 4 weeks post surgery. At 1 week, whole-brain Na, K-ATPase mRNA levels were depressed for all isoforms (alpha1 approximately beta1>alpha2>alpha3). No changes were observed in the hypothalamus. At 4 weeks, the mRNA levels of all alpha isoforms were significantly increased in the whole brain and these changes were paralleled by an increase of alpha2 and alpha3 transcript in the hypothalamus. beta1 mRNA expression was increased in the hypothalamus only. The alpha-isoform protein expression generally changed in the same direction as mRNA changes at both 1 and 4 weeks, as did alpha1 enzyme activity at 1 week and the combined alpha2/alpha3 enzyme activities at 4 weeks. Since inhibition of brain Na, K-ATPase increases sympathetic nervous system (SNS) activity and blood pressure, the decreases in brain Na, K-ATPase expression and activity at 1 week post SRC may contribute to the hypertension during its developmental phase, while the increase in the alpha2/alpha3 brain expression and activity at 4 weeks may be a compensatory response to established hypertension.

Animals↗
PubMed2003

Sleep patterns over 21-day period in rats with chronic constriction of sciatic nerve.

The main purpose of the present study was to examine sleep patterns over 21-day periods of rats in a peripheral neuropathy model induced by sciatic nerve constriction. Evaluation of the recordings showed that chronic constrictive injury (CCI) induced sleep alterations such as reduced sleep efficiency and increased number of arousals, especially during the light period. Among these alterations, sleep patterns were most affected between day 2 and day 10. The rats took longer to get to sleep from day 2 to 7 days after the CCI in the light period. Additionally, latency to the first paradoxical sleep episode was reduced in the second to fourth day after CCI in both light and dark period recordings. In conclusion, sciatic nerve constriction induced poor sleep quality with disrupted sleep in rats, particularly during the first week of that condition.

Animals↗
PubMed2002

Reactive oxygen species in sustained airway constriction induced by citric acid aerosol inhalation.

We tested if there is a direct relationship between reactive oxygen species and citric acid-induced airway constriction. Guinea pigs were divided into two groups: control and dimethylthiourea (a hydroxyl radical scavenger). The animals in each group were further separated into four subgroups: baseline, recovery 2-3 min, recovery 10 min, and recovery 20 min. Each animal was anesthetized, cannulated, paralyzed, and artificially ventilated. Citric acid aerosol inhalation caused the following significant changes in the control group during the recovery period: airway constriction for at least 20 min, increases in luminol-amplified t-butyl hydroperoxide-initiated chemiluminescence counts in the bronchoalveolar lavage samples at 2-3 and 20 min, an increase in bronchoalveolar lavage fluid substance P level at 2-3 min, and elevations in the bronchoalveolar lavage fluid total cell and neutrophil numbers at 20 min. All citric acid-induced alterations were prevented by dimethylthiourea pretreatment. These results suggest that citric acid inhalation induces the initial release of reactive oxygen species and tachykinins, which causes further cellular infiltration and sustained airway constriction.

Administration, Inhalation↗