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PubMed2000

Morphological characterization of bicontinuous structures in polymer blends and microemulsions by the inverse-clipping method in the context of the clipped-random-wave model.

A method is proposed to determine the spectral function of the clipped-random-wave (CRW) model directly from scattering data. The spectral function f(k) (k is a wave number) gives the distribution of the magnitude of wave vectors of the sinusoidal waves that describes the essential features of the two-phase morphology. The proposed method involves "inverse clipping" of a correlation function to obtain f(k) and does not require any a priori assumptions for f(k). A critical test of the applicability of the inverse-clipping method was carried out by using three-component bicontinuous microemulsions. The method was then used to determine f(k) of the bicontinuous structure of a phase-separating polymer blend. f(k) for the polymer blend turned out to be a multipeaked function, while f(k) for the microemulsions exhibits a single broad maximum representing periodicity of the morphology. These results indicate the presence of the long-range regularity in the morphology of the polymer blend. Three-dimensional (3D) morphology corresponding to the scattering data of the polymer blend was generated using the CRW model together with the multipeaked f(k). Interface curvatures of the 3D morphology calculated from f(k) were measured and compared with those experimentally determined directly from the laser scanning confocal microscopy in the same blend.

Journal Article↗

PubMed1996

Aneurysm clip testing for ferromagnetic properties: clip variability issues.

To assess ferromagnetic properties of intracranial aneurysm clips reported to be nonferromagnetic, 1,765 Yasargil, 11 Sugita, and 15 Perneczky aneurysm clips were studied for rotation or translation on plate glass in a 1.5-T MR imager. Sixty-three clips (52 Yasargil, 11 Perneczky) weakly reoriented along the static magnetic resonance (MR) field. These results confirm the need for standardized testing for ferromagnetic properties for implantable metallic devices.

Contraindications↗

PubMed1996

Coil placement after clipping: endovascular treatment of incompletely clipped cerebral aneurysms. Report of two cases.

In up to 4% of patients whose aneurysms are microsurgically clipped, there is an expected or unexpected aneurysm residuum. The authors describe two patients in whom surgical clipping did not result in complete obliteration of the aneurysm sac and in whom a second operation was not believed to be the solution to the problem. In both patients complete occlusion of the aneurysm residuum was achieved via an endovascular approach. Using the Guglielmi detachable coil system, it was possible to place two platinum coils selectively into the aneurysms. The endovascular approach may be a good treatment option for all patients in whom surgical clipping does not result in complete obliteration of the aneurysm sac and reoperation is contraindicated or unacceptable to the patient.

Adult↗

PubMedDate not supplied

Voluntary alcohol intake is attenuated in two-kidney, one-clip, but not in one-kidney, one-clip Goldblatt hypertensive rats.

Voluntary alcohol intake was examined in two models of renovascular hypertension known to differ in their effects on the renin-angiotensin system. In experiment 1, Two-Kidney, One-Clip (renin-dependent) hypertensive rats (T-K,O-C) or their sham operated controls were offered limited access to alcohol for 1 hr each day. Over a four week period the T-K,O-C rats drank significantly less 3% and 6% (w/v) alcohol solution than the sham operated controls. In experiment 2, One-Kidney, One-Clip (renin-independent) hypertensive rats or their sham operated controls were offered alcohol on a similar limited access basis. Over a four week period, the O-K,O-C rats did not show a reduction in the intake of either a 3% or 6% alcohol solution compared to the sham operated controls. These results provide further documentation for the role of the renin-angiotensin system in modulating alcohol intake. The process by which this system might influence alcohol intake is outlined.

Alcohol Drinking↗

PubMed2006

Postoperative three-dimensional CT angiography after cerebral aneurysm clipping with titanium clips: detection with single detector CT. Comparison with intra-arterial digital subtraction angiography.

AIM: To assess the significance of three-dimensional computed tomography angiography (3D-CTA) in detecting remnant necks after cerebral aneurysm clipping. MATERIALS AND METHODS: A total of 59 patients (77 aneurysms) underwent surgery using titanium clips. Two blinded observers independently evaluated the presence of neck remnants on shaded-surface display (SSD) imaging, volume rendered (VR) imaging, and intra-arterial digital subtraction angiography (IADSA). RESULTS: Mean sensitivity and specificity for detecting neck remnants were 50.0 and 74.2% for SSD imaging, 61.5 and 82.8% for VR imaging, and 92.3 and 92.2% for IADSA, respectively. Receiver operating characteristic (ROC) analysis revealed excellent diagnostic performance for IADSA [mean area under ROC curve (Az)=0.97], and good diagnostic performance for 3D-CTA (Az=0.70 and 0.76 for SSD and VR, respectively). Specificity of VR was better than that SSD (p=0.082), however, there was no significant difference between them. CONCLUSION: Use of 3D-CTA techniques can facilitate postoperative evaluation.

Adult↗

PubMed2005

Outcome of surgical clipping for ruptured, low-grade, anterior circulation cerebral aneurysms: should clipping be omitted after International Subarachnoid Aneurysm Trial?

BACKGROUND: A recent randomized trial for ruptured aneurysm resulted in poorer outcomes for the surgical group than the endovascular group. However, the surgical results seemed to be worse than could be expected for experienced neurosurgeons in Japan. We therefore analyzed our own surgical results and evaluated them for a comparison with the trial results. METHODS: Data on patients with ruptured, small, anterior circulation aneurysms in good clinical condition (World Federation of Neurological Surgeons grade I or II) and treated with surgical clipping were obtained from various discharge databases for 1997 to 2001, and their outcomes were analyzed in a retrograde fashion. RESULTS: Of the total of 487 patients, 17.6% showed a poor outcome (modified Rankin Scales 3-6) at discharge, and after 1 year, 6.1% remained in poor clinical condition. However, fewer patients were in poor condition both at discharge and after 1 year compared with the surgical and endovascular results for patients entered in the International Subarachnoid Aneurysm Trial. Complete occlusion of the aneurysm was attained in 93.6% of our patients. Rebleeding from the treated aneurysm occurred in 0.6%, and there was no rebleeding after 1 year. CONCLUSIONS: Surgical clipping is a safe and reliable treatment and can be the first choice for small ruptured aneurysms of the anterior circulation with a good grade.

Adolescent↗

PubMed1988

Synthesis of catecholamines in the hypothalamus and brainstem in one-kidney, one clip and two-kidney, one clip hypertension in rabbits.

In order to examine the role of central catecholaminergic neurons in hypertension, the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamines, was studied in the hypothalamus, midbrain, pons-upper medulla, mid-medulla and lower medulla of one-kidney, one clip (1-K,1C) and two-kidney, one clip (2-K,1C) hypertensive rabbits and their respective operated controls (1-K,1 Cc and 2-K,1 Cc). Comparing the 1-K,1 C group to the 1-K, 1 Cc group, the activity of TH was increased by 79% in the hypothalamus (P less than 0.02), 37% in the mid-medulla region (P less than 0.02) and was unchanged in the midbrain, pons-upper medulla and the lower medulla. Comparing the 2-K,1 C group to the 2-K,1 Cc group, the activity of TH was increased by 89% in the mid-medulla (P less than 0.01), decreased by 36% in the pons-upper medulla (P less than 0.01) and unchanged in the hypothalamus, midbrain and lower medulla. These results indicate that similarities and differences exist in the contribution of central catecholaminergic neurons to the pathophysiology of 1-K,1 C and 2-K,1 C hypertension in rabbits.

Animals↗

PubMed2005

Small bowel perforation due to a plastic bread bag clip: the case for clip redesign.

Complications of ingested plastic bread bag clips include small bowel perforation, obstruction, dysphagia, gastrointestinal bleeding and colonic impaction. There have been at least 10 cases of small bowel perforation reported in the published literature. The present paper reports this unusual cause of bowel perforation, which we believe could be prevented by improving the design of this relatively modern device or even by changing the method of sealing bread bags altogether. Interestingly, the date on the offending bread bag clip preceded the presentation of the patient by 2.5 years.

Diagnosis, Differential↗

PubMedDate not supplied

Distributions of microvascular pressure in skeletal muscle of one-kidney, one clip, two-kidney, one clip, and deoxycorticosterone-salt hypertensive rats.

Studies were performed on the cremaster skeletal muscle in rats to investigate the microvascular changes that are associated with established one-kidney, one clip (1K1C) and two-kidney, one clip (2K1C) Goldblatt hypertension and with deoxycorticosterone (DOC)-salt hypertension. Rats were anesthetized with urethane and chloralose; and cremaster muscles with intact circulation and innervation were suspended in a controlled Krebs bath. Microvascular pressures and vessel diameters were measured at three consecutive arteriolar (A) and venular (V) branch levels. Arteriolar diameters (means +/- SEM) in normotensive (NT) rats were 119 +/- 7, 86 +/- 5, and 31 +/- 3 micron respectively for 1A, 2A, and 3A arterioles; and venule diameters were 218 +/- 12, 141 +/- 15, and 53 +/- 7 micron respectively for 1V, 2V, and 3V venules. As compared to NT rats, there was a selective decrease in lumen size (percent reduction from control) for 1A and 2A (23% to 38%) in 1K1C and 2K1C rats and for 1A, 2A, and 3A (42% to 44%) in DOC rats. Venule diameters were not significantly different between normotensive and hypertensive animals at any branch level. Femoral artery pressures were significantly elevated (greater than or equal to 43%) in all three forms of hypertension; however, this increase in pressure was not proportionally transmitted throughout the microcirculation. This was evidenced by normal pressure in 3A arterioles and in all venules for 1K1C and 2K1C rats and by normal pressures in 3V and larger venules for DOC rats. Our findings indicate that elevated arterial pressure in chronic renal hypertension is not transmitted uniformly across all microvascular segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗

PubMed1983

Different mechanisms maintaining high blood pressure in chronic one-kidney, one-clip, and two-kidney, one-clip hypertensive rats.

To evaluate the difference of the blood pressure regulating mechanisms of chronic (12-14 weeks) one-kidney, one-clip (1K-1C) and chronic two-kidney, one-clip (2K-1C) hypertensive rats, we administered captopril, captopril plus indomethacin, and indomethacin to the rats. Pretreatment values of plasma renin concentration, plasma aldosterone concentration and urinary kallikrein excretion were significantly higher in 2K-1C than in 1K-1C hypertensive rats. Captopril-induced blood pressure reduction was greater in 2K-1C than in 1K-1C hypertensive rats. When captopril was administered to the rats treated with indomethacin, captopril-induced blood pressure reduction was attenuated only in 2K-1C hypertensive rats. Indomethacin produced renal impairment and further raised the blood pressure in 1K-1C hypertensive rats, but did not in 2K-1C hypertensive rats. These results suggest that the renin-angiotensin system functions to maintain high blood pressure more predominantly in chronic 2K-1C than in 1K-1C hypertensive rats. The renal kallikrein-kinin system is suppressed in chronic 1K-1C hypertensive rats but not in 2K-1C hypertensive rats. The renal prostaglandin system is more important for regulating the renal circulation in chronic 1K-1C than in 2K-1C hypertensive rats.

Aldosterone↗

PubMed1992

In vivo left ventricular anatomy in rats with two-kidney, one clip and one-kidney, one clip renovascular hypertension.

OBJECTIVES: To evaluate differences in left ventricular structural changes related to different hemodynamic patterns. DESIGN: One-kidney, one clip (1K1C; volume-dependent hypertension) rats were two-kidney, one clip (2K1C; high-resistance hypertension) to determine whether these two types of Goldblatt rats showed different types of left ventricular adaptation. METHODS: M-mode echocardiography was used to study 28 2K1C and 19 1K1C Wistar rats 8 weeks after surgery and 55 age-matched control animals. RESULTS: Systolic blood pressure was equally high in the two models; the 1K1C rats had a larger left ventricular chamber and normal plasma renin activity (PRA), whereas in the 2K1C rats PRA was increased and the left ventricular chamber was normal. The atrial natriuretic factor was significantly increased only in the 2K1C rats and was related to PRA. The left ventricular mass index was increased in both models, but more in the 1K1C than the 2K1C rats. CONCLUSIONS: In both models the degree of left ventricular hypertrophy was associated with the interacting effects of the hemodynamic component superimposed on the primary hemodynamic pattern (i.e. blood pressure as an expression of pressure overload in the primarily volume-dependent 1K1C rats and the left ventricular chamber size as an expression of volume overload in the high-resistance 2K1C rats). The interaction between pressure and volume increased the left ventricular wall thickness in both models, with additional chamber enlargement in the 1K1C rats. In these rats, the increase in left ventricular mass was more pronounced due to the greater volume load on the heart.

Adaptation, Physiological↗

PubMed1994

[Migrating clips--a complication of laparoscopic sterilization with Filshie clips].

The most common method for female sterilization in Denmark is laparoscopic tubal application of Filshie clips. We describe a case of a 35 year old women admitted with a right inguinal abscess. A Filshie clips that had been inserted five years earlier was found by surgical exploration of the abscess. Possible pathogenetic and etiological factors are discussed.

Adult↗

PubMed2002

Nasal septal clip (Ciğdem clip).

We report the use of a nasal septal clip. We believe that this instrument is more easily inserted and removed when compared with the classical nasal packs.

Equipment Design↗

PubMed1953