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PubMed1971

Demonstration of independent roles of proximal tubular reabsorption and intratubular load in the phenomenon of glomerulotubular balance during aortic constriction in the rat.

The mechanism of glomerulotubular balance was investigated by microperfusion of the rat proximal tubule at two different rates before and after contriction of the aorta sufficient to produce a 50% reduction in whole kidney filtration rate and plasma flow. At a perfusion rate of 28 nl/min the absolute rate of proximal tubular reabsorption averaged 4.80+/-0.28 nl/mm.min in the absence of aortic constriction. Reducing the perfusion rate by one-half resulted in only a 22% decrease in the absolute rate of reabsorption, and imbalance between load and reabsorption resulted as fractional reabsorption of the perfused volume increased from 0.56 to 0.83 at 3 mm length of perfused tubule. These observations support other studies indicating that changing the load presented to the individual proximal tubule does not change reabsorptive rate sufficiently to result in glomerulotubular balance. Aortic constriction decreased the absolute rate of proximal tubular reabsorption approximately 50%, resulting in imbalance between load and reabsorption at the higher perfusion rate (fractional reabsorption of the perfused volume fell to 0.23 at 3 mm). Thus, the decrease in proximal tubular reabsorption necessary for glomerulotubular balance will occur independent of a change in the load presented for reabsorption. Balance between load and reabsorption was produced artificially by combining aortic constriction and a reduction in perfusion rate proportional to the reduction in whole kidney filtration rate. Mathematical analysis of the data suggests that the absolute rate of reabsorption along the accessible length of the proximal tubule is constant and is not proportional to the volume of fluid reaching a given site. Thus, there appears to be no contribution to glomerulotubular balance of any intra- or extratubular mechanism directly coupling load and the rate of proximal tubular reabsorption. It is concluded that glomerulotubular balance during aortic constriction is a consequence of hemodynamic effects of the maneuver to decrease filtration rate and the rate of proximal tubular reabsorption independently but in an approximately proportional manner.

Animals↗
PubMed1996

Cause of eustachian tube constriction during swallowing in patients with otitis media with effusion.

In order to clarify the cause of the constriction of the eustachian tube during swallowing that is often seen in patients with otitis media with effusion, video endoscopy of the pharyngeal orifice of the eustachian tube was performed and superimposed with videograms of the tubal airflow and resistance, which were simultaneously examined by the forced response test. In children with otitis media with effusion (17 ears), when the eustachian tube constricted on the videogram on swallowing, the tubal orifice was found to be squeezed between an elevated soft palate and a hypertrophied adenoid (7/17), squeezed between an elevated soft palate and edema of the posterior lip (7/17), or blocked by nasal discharge (5/17). In adults with otitis media with effusion (7 ears), edema of the posterior lip (5/7) was the main cause of the constriction of the tubal orifice during swallowing. Inflammation in the nasopharynx and the pharyngeal portion of the eustachian tube was considered to be closely related to the tubal constriction, which represents a considerable part of the cause of tubal ventilatory dysfunction in otitis media with effusion.

Adult↗
PubMed1985

Characteristic morphology of the constricted fetal ductus arteriosus following maternal administration of indomethacin.

Indomethacin 10 mg/kg was administered to the maternal rat on the 21st day of pregnancy, and the fetal and neonatal ductus arteriosus were studied using the rapid whole-body freezing technique. The sagittal section of the frozen thorax disclosed characteristic localized constriction at the aortic end of the fetal ductus at 24 h after administration of indomethacin. Proximal dilatation of that fetal ductus persisted for more than 4 h after birth, and disappeared gradually. Shortening of the ductal length was associated with both intrauterine constriction by indomethacin in experimental rats and neonatal physiologic constriction of control rats, but significantly greater shortening was seen with intrauterine constriction.

Animals↗
PubMed2001

Real-time imaging of cell-cell adherens junctions reveals that Drosophila mesoderm invagination begins with two phases of apical constriction of cells.

Invagination of the epithelial cell sheet of the prospective mesoderm in Drosophila gastrulation is a well-studied, relatively simple morphogenetic event that results from dynamic cell shape changes and cell movements. However, these cell behaviors have not been followed at a sufficiently short time resolution. We examined mesoderm invagination in living wild-type embryos by real-time imaging of fluorescently labeled cell-cell adherens junctions, which are located at the apical zones of cell-cell contact. Low-light fluorescence video microscopy directly visualized the onset and progression of invagination. In an initial period of approximately 2 minutes, cells around the ventral midline reduced their apical surface areas slowly in a rather synchronous manner. Next, the central and more lateral cells stochastically accelerated or initiated their apical constriction, giving rise to random arrangements of cells with small and relatively large apices. Thus, we found that mesoderm invagination began with slow synchronous and subsequent fast stochastic phases of cell apex constriction. Furthermore, we showed that the mesoderm invagination of folded gastrulation mutant embryos lacked the normal two constriction phases, and instead began with asynchronous, feeble cell shape changes. Our observations suggested that Folded gastrulation-mediated signaling enabled synchronous activation of the contractile cortex, causing competition among the individual mesodermal cells for apical constriction. Movies available on-line: http://www.biologists.com/JCS/movies/jcs2073.html

Animals↗
PubMed1994

Histochemistry and immunohistochemistry of extracellular matrix of rat fetal Ductus arteriosus during the indomethacin-induced constriction.

Administration of anti-inflammatory non-steroidal drugs to pregnant animals causes constriction of the fetal ductus arteriosus (DA). To clarify the mechanism of the indomethacin-induced constriction of the rat fetal DA, extracellular matrix (ECM) components were observed by immunohistochemical techniques with antibodies 2B1, 6B6, 3B3, 9A2 and others to various kinds of proteoglycans (PGs). In the 10mg/kg group, the large PG revealed with antibody 2B1 was increased in the inner and outer media at constriction, and chondroitin 6-sulfate PG was strongly immunostained with antibody 3B3 as granular substances in the outer media, although no difference in stainability of chondroitin 4-sulfate PG revealed with the antibody 9A2 was observed between experimental and control groups. This suggests that the cells composing the fetal DA showed a tendency of proliferation and resultant production and aggregation of large PG with chondroitin 6-sulfate chains during constriction induced by indomethacin-treatment.

Animals↗
PubMed2004

Prognostic value of epicardial coronary artery constriction to the cold pressor test in type 2 diabetic patients with angiographically normal coronary arteries and no other major coronary risk factors.

OBJECTIVE: Endothelium-dependent coronary dilation is impaired in diabetic patients and has been found to independently predict cardiovascular events (CVEs) in patients with multiple coronary risk factors. The aim of this study was to evaluate the outcome of type 2 diabetic patients on the basis of epicardial coronary dysfunction. RESEARCH DESIGN AND METHODS: We examined 56 control subjects (aged 51.7 +/- 6.4 years) using coronary artery response to the cold pressor test (quantitative coronary angiography) and compared them with 72 type 2 diabetic patients (aged 50.3 +/- 8.5 years) without other major coronary risk factors. RESULTS: Average diameter change was 17.2 +/- 10.4% in the control subjects, dilation occurred in 91.1% of subjects, no change occurred in 8.9%, and there was no constriction. Average diameter change was -14.4 +/- 12.1% in diabetic patients (P < 0.001 vs. control subjects), constriction occurred in 73.6%, no change occurred in 26.4%, and there was no dilation. CVEs were recorded with a mean follow-up of 45 +/- 19 months. There was 1 CVE in the control group and 26 CVEs in 18 of 72 diabetic patients (P < 0.001 vs. control subjects), with 23 events in 16 of 53 diabetic patients with coronary artery constriction (P < 0.001 vs. control subjects), and 3 events in 2 of 19 diabetic patients with no diameter change (NS vs. control subjects). CONCLUSIONS: In type 2 diabetic patients without other major coronary risk factors, constriction of angiographically normal coronary arteries to the cold pressor test is predictive of long-term CVEs.

Age of Onset↗
PubMed1975

Effects of renal lymphatic occlusion and venous constriction on renal function.

The effects of renal lymphatic occlusion or increased lymph flow due to renal vein constriction on renal function were investigated in rats. In each experiment, the renal lymphatics or vein of the left kidney were occluded or constricted and the right kidney served as a control. Occlusion of renal lymphatics caused renal enlargement, no change in glomerular filtration rate, a marked increase in urine flow and solute excretion without any change in urine osmolality, and enhanced urinary loss of urea, potassium, sodium and ammonium. Urea concentrations in medullary and papillary tissues were significantly elevated. Renal vein constriction caused renal enlargement and a marked drop in glomerular filtration rate, urine volume, urine osmolality and solute excretion. tissue concentrations of urea and potassium were decreased in the medulla and papilla and total tissue solute was significantly decreased in the papilla. The data indicate that in the rat, renal lymphatic occlusion traps urea in the medulla and induces a urea diuresis resulting in a large flow of normally concentrated urine. On the other hand, increased lymph flow secondary to renal vein constriction decreases medullary urea and potassium concentrations and papillary osmolality. These changes and the reduced glomerular filtration rate result in a small flow if dilute urine. Thus both renal lymphatic occlusion and enhanced lymph flow have a significant effect on renal function.

Ammonia↗
PubMed2001

Long-term outcome of patients with ergonovine induced coronary constriction not associated with ischemic electrocardiographic changes.

OBJECTIVES: This study investigated the long-term outcome of patients with coronary artery constriction induced with ergonovine but not associated with ischemic electrocardiographic changes. METHODS: The ergonovine provocation test was performed in 419 patients with suspected but unproven variant angina. Ergonovine maleate was administered into the coronary arteries at 8 micrograms/min for 5 min during cardiac catheterization. Patients were categorized into three groups according to their response to ergonovine. The positive group contained patients who developed coronary constriction of more than 90% in diameter associated with ischemic electrocardiographic changes and chest pain. The intermediate group contained patients who had coronary constriction of more than 90% but no electrocardiographic changes. The negative group contained patients who had neither significant coronary constriction nor ST segment changes. RESULTS: There were 305 patients, 49, and 65 in the negative, intermediate, and positive groups, respectively. Death occurred in six patients (2%), one (2%), and one (2%) in the negative, intermediate, and positive groups, respectively. Sudden cardiac death occurred in one patient in the negative group. Recurrence of chest pain with effectiveness of sublingual administration of nitroglycerine was observed in 26 patients (9%), 10 (20%), and 11 (17%) in the negative, intermediate, and positive groups, respectively. CONCLUSIONS: Some patients in the intermediate group might show "false negative" response to ergonovine so careful treatment with calcium antagonists should be continued in patients in the intermediate group as well as patients with vasospastic angina.

Coronary Angiography↗
PubMed1992

Endothelins constrict guinea pig tracheas by multiple mechanisms.

When tracheal rings isolated from guinea pigs were treated with endothelins (ETs), a dose-dependent constriction was observed and measured isometrically. ET potencies were ET-1 = ET-2 greater than ET-3. Dose-response curves of epithelium-denuded tracheas were shifted to the left by approximately one order of magnitude. Lung tissue contained saturable binding sites to 125I-labeled ET-1. These binding sites were replaced by ET-1 = ET-2 greater than ET-3. Because the airway tissue contained primarily ET-1 as measured by immunoassay after high-performance liquid chromatography separation, we investigated the mechanism of ET-1-induced tracheal constriction. Tracheal constriction induced by ET-1 required Ca++ in the medium. Because suppression of the contractile response by nicardipine and diltiazem was small, Ca++ entry appeared to be gated primarily through Ca++ channels rather than via voltage-dependent ones. FPL55712, SC47014A, indomethacin and OKY046 suppressed the dose-response curves, suggesting that lipid mediators are formed in response to ET-1. Diphenhydramine also altered dose-response curves, suggesting that histamine release from mast cells was partially responsible for the constriction. Pretreatment of tracheas with compound 48/80 resulted in suppression of the contractile responses. Furthermore, the combination of indomethacin, FPL55712 and diphenhydramine gave essentially identical effects. Our observations suggest that ET-1 provokes the contractile response of guinea pig tracheas not only by direct actions on smooth muscle but also by indirect actions through production of chemical mediators in mast cells and other inflammatory cells.

Animals↗
PubMed2004

[Constriction effect of daidzein on guinea pig's gall bladder].

OBJECTIVE: To study the effect of daidzein on gall bladder constriction. METHODS: To study daidzein how to antagonize the gall bladder constriction of guinea pig induced by acitylcholine, histamine, excessive K+ or Ca2+. RESULTS: It has been found that daidzein could remarkedly antagonize the gall bladder constriction of guinea pig induced by acitylcholine, histamine, excessive K+, cumulation Ca2+. CONCLUSION: Daidzein could obviously antagonize gall bladder constriction in guinea pig.

Acetylcholine↗
PubMed2004

[The evaluation for the therapeutic effect and the clinical practicability of encircling constriction of superficial femoral vein in the treatment of primary deep venous insufficiency].

OBJECTIVE: To evaluate the therapeutic effect and the clinical practicability of encircling constriction of superficial femoral vein in the treatment of primary deep venous insufficiency (PDVI). METHODS: Ninety-seven limbs in 97 patients who were proved to be PDVI by ascending venography were divided into Group A (79 limbs) and Group B (18 limbs). Patients of Group A were treated with the encircling constriction of venous wall at the first valve of superficial femoral veins. And they were also treated with the high ligation and ablation of great saphenous vein, ablation of superficial veins and ligation of perforator veins at the same time. Patients of Group B were simply treated with the high ligation and ablation of great saphenous vein, ablation of superficial veins and ligation of perforator veins. Ascending venography and CEAP classification and clinical scoring were proceeded from two months to six years after operation to evaluate the effect of the operation. RESULTS: The difference between preoperative and postoperative scores of Group A and Group B were both remarkable (Group A, P < 0.01; Group B, P < 0.05). The difference of scores, which equated to preoperative scores minus postoperative score, between Group A and Group B were also prominent (P < 0.01). Post-operation ascending venography was performed on 67 limbs in Group A. The effective rate of the operation is 83.58% (28 + 28/67), obviously effective rate is 41.79% (28/67). Same exam was performed on 12 limbs in Group B and the effective rate of the operation is 33.33%. The difference between two groups' effective rate is significant (P < 0.05). CONCLUSIONS: Clinical scoring of Group A decreased much more than Group B; The effective rate of Group A in ascending venography is also much higher than Group B. Encircling constriction of superficial femoral vein is useful to relief the symptom and recover the shape and function of the valve of superficial femoral veins. Those who are diagnosed to be PDVI by means of pre-operation ascending venography and Valsalva test should accept the operation of the encircling constriction of superficial femoral vein.

Adult↗
PubMedDate not supplied

[Experimental study of accuracy of electro-odontometric device in establishment of apical constriction of a root canal].

The aim of the present study was to investigate the accuracy of an electro-odontometric device "Odontometer" (Goof, Denmark) in the determination of the exact location of the apical constriction in root canals of extracted teeth in experimental conditions. Ninetynine root canals of 91 teeth were used. Following the access to the root canal the teeth were sealed at the level of the cemento-enamel junction in the apertures of a plastic plate. Each plate contained ten tooth samples. The plate was immersed into a gelatine medium. The roots were completely immersed but the crowns were isolated from the medium by the plastic plate and sticky wax seal, remaining at the top surface of the plate. The platinum plate was immersed in the gelatine medium and connected to the passive electrode of the device. The active electrode was a K-reamer n. 15 which was advanced along the canal until "Odontometer" indicated "apical constriction". At this point the reamer was sealed in the canal, and the toot was released from the apparatus. The apical third of the root was then ground parallel to the long axis until the distal segment of the K-reamer and the root canal appeared. The distance between the tip of the reamer and the apical constriction was measured with a microscope precision of 0.125 mm. The absolutely exact location of the apical constriction was determined in 22% of cases. In no case the endocanal electrode passed over the anatomic foramen. With the tolerance of the clinically acceptable odontometric error of 0.5 mm, "Odontometer" was accurate in 83% of cases thus its use in current dental practice is justified.

Dental Pulp Cavity↗
PubMedDate not supplied

[Electroodontometric determination of location of apical constriction in root canal].

Electronic odontometer (Goof, Denmark) was used in clinical investigation of 169 root canals of 138 teeth, treated for different endodontic reasons. A removable plastic collar was fixed to endocanal electrode (K-reamer) on which the exact length was signalized as apical constriction, followed by radiographic control. The obtained values were statistically elaborated. The exact location of apical constriction was accurately determined in 119 cases (70.41%). Electroodontometer errors were found in 50 root-canals, and deviation ranged from -4 mm to -1 mm with mean of -0.3254 +/- 0.85. The predominant error was failure of the apical constriction (39 cases); in a few samples (11) a canal instrument passed through this location. When pulpo-periodontal condition was considered the greatest number of errors was found in teeth with vital pulp tissue and a significantly smaller number in teeth with gangrenous pulp with or without periapical lesions. The age of sample had no influence on the accuracy of determination of the location of apical constriction.

Dental Pulp Cavity↗
PubMed1995

Effect of a combination of coumarin derivatives and rutoside on venous and lymphatic circulations during severe constriction of the caudal vena cava in rabbits.

The effect of a coumarin (CAS 91-64-5) derivatives-rutoside (CAS 153-18-4) combination (Esberiven) has been investigated in an in vivo model of venous hind leg stasis elicited by severe constriction of the caudal vena cava in anesthetized rabbits. The vena cava flow is initially reduced by 80% compared to reference values; then, it significantly declines over time. The venous femoral pressure drops as well as the perfusion pressure whereas the peripheral resistance increases. The popliteal lymph flow gradually slows down after the constriction. Moreover, this venous constriction results in a marked reduction of the right ventricular stroke volume responsible for a left ventricle failure and for the exitus of 30% of the rabbits within 1-3 h post-constriction. A 5-day pretreatment (i.v.) with the coumarin derivatives-rutoside combination at a dose of 4 mg of coumarin derivatives + 200 mg of rutoside/rabbit/day increases the lymph flow but does not suppress the mechanically-induced venous flow decrease. The 6th-day treatment (infusion at the respective doses of 5 mg of coumarin derivatives + 250 mg of rutoside/kg or 10 mg of coumarin derivatives + 500 mg of rutoside/kg) induces a dose-related significant increase of both venous and lymph flows and of the femoral pressure. At the same time, the peripheral venous resistance decreases in a dose-response relationship. Furthermore, after administration of coumarin derivatives and rutoside, the right ventricle stroke volume increases and no death occurs.

Animals↗
PubMedDate not supplied

Congenital constriction band syndrome. Pathophysiology and treatment.

The clinical manifestations of 88 children with congenital constriction band syndrome involvement of the hand were reviewed. Seventy-five of these children had evidence of digital or limb amputations, with 235 upper limb amputations and 138 lower limb amputations. In the hand, digital amputations were most common in the index, middle, and ring fingers, whereas in the foot, amputations of the hallux were most often noted. Band indentation was often present at multiple levels. Proximal bands may be associated with neural compression. Syndactyly was invariably associated with a proximal interdigital sinus or cleft and was frequently associated with distal amputation. Examination of a 27-week gestation stillborn specimen having manifestations of congenital constriction band syndrome demonstrated the intrauterine biologic response to band constriction. The variable clinical manifestations of congenital constriction band syndrome can best be explained as the response of the growing, embryologically defined limb to intrauterine deformation or band-induced compression and ischemia.

Abnormalities, Multiple↗
PubMed1997

Visual field constriction as a cause of blindness or visual impairment.

Reported are the results of a study of onchocerciasis in communities mesoendemic for savanna onchocerciasis in Kaduna State, northern Nigeria. The study involved 6831 individuals aged > or = 5 years who underwent an extensive screening examination for visual function including Friedmann field analysis. A total of 185 (2.7%) were bilaterally blind by acuity and an additional 28 (0.4%) were blind by visual field constriction. Also 118 (1.7%) individuals were visually impaired by acuity criteria. No criteria for visual impairment by field constriction have been established, and we therefore investigated three potential criteria. As a result, a further 60 (0.9%) individuals were identified with significant visual impairment due to field loss by the various definitions. Small islands of remaining peripheral field occurred in 50 individuals, while 40 individuals had marked reduction of binocular visual field below the horizontal meridian. Concentric visual field constriction to < 20 degrees was found in seven individuals. The WHO definition of blindness currently includes visual field damage criteria for blindness but not for visual impairment. Visual field loss is recognized as a major disability. We hope that these findings stimulate international discussion leading to the development of satisfactory definitions for visual impairment by visual field constriction.

Adolescent↗
PubMed1997

[Compensatory enlargement versus chronic constriction. The two features of vascular remodelling after experimental angioplasty].

Considerable efforts have been made to prevent post-angioplasty restenosis targeted mainly against a pathogenesis suggesting a dominant role of hyperplasia. We and others have already shown that constrictive remodelling plays a major role in restenosis. This article evaluates not only the constrictive remodeling theory but also compensatory enlargement associated with prevention of restenosis. The present study on 33 rabbits used the following protocol. Four weeks after inducing an atherosclerotic lesion by air-dessication of a femoral artery segment and a high cholesterol diet, angioplasty was performed. The angiographic minimal luminal diameter significantly increased after angioplasty. Three to four weeks later, initial gain was significantly lost. Restenosis was quantified histologically as well as a remodelling index and a hyperplasia index. No correlations were observed between degree of stenosis and hyperplasia present at the same degree in animals with and without restenosis. On the other hand, there was a strong correlation between restenosis and constrictive remodelling, and with absence of restenosis and compensatory enlargement. Moreover, there was significant a correlation between the degree of hyperplasia and the compensatory remodelling. These data point to the double nature of remodelling: compensatory enlargement observed in animals without restenosis, and constrictive remodelling, the principal mechanism observed in animals with restenosis.

Angioplasty, Balloon↗
PubMed1998

Clubfoot deformity in congenital constriction band syndrome: manifestations and treatment.

Clubfoot deformity associated with congenital constriction band syndrome (CCBS) has different characteristics than classic idiopathic clubfoot, and is more difficult to treat. We describe the manifestations, treatment, and outcomes of nine patients treated for 11 CCBS-associated clubfoot deformities between 1980 and 1993. All but one of these children had an abnormal gestational or neonatal history. From an assessment of the correctability of the deformity and the associated secondary changes, the clubfoot severities were all classified as grade B (intermediate). The constriction bands in eight clubfeet were classified as type 0 (5 feet), II (2), or III (1), according to the location and depth of the band. Band types in three feet were unclassified because the band release was performed at other hospitals. We released the bands before correcting the clubfeet in the two patients with type II bands. The five patients with type 0 bands received casting first but with poor response. All clubfeet were corrected surgically; the procedures were posteromedial release in 10 feet, split tibialis anterior tendon transfer in five, and lengthening of the Achilles tendon in three. At an average follow-up of 3.8 years, seven of the 11 clubfeet were classified as having good results and four as fair. Among the six clubfeet with constriction bands on the ipsilateral leg, five were classified as having good results and one as fair. Two of the five clubfeet without constriction bands on the ipsilateral leg had good results and three had fair results. The presence of a band did not influence the final outcome of the clubfoot deformity (p > 0.05). In the five patients with forefoot varus deformity due to peroneal weakness, tibialis anterior tendon transfer successfully corrected the deformity. All the clubfeet treated in this series were plantigrade after treatment and had satisfactory results.

Amniotic Band Syndrome↗