Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Clips”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1987

Divided renal and caval vein plasma renin activity in two-kidney two-clip hypertension in rabbits and variations of blood pressure, plasma volume and renal function following unilateral nephrectomy.

Determinations were made of peripheral plasma renin activity, blood pressure, plasma volume and blood urea nitrogen in rabbit models of two-kidney one-clip, two-kidney two-clip or one-kidney one-clip hypertension that were created by staged operation to produce functionally significant renal artery stenosis. The plasma renin activity in the divided renal veins and inferior caval vein was also measured in animals with two-kidney two-clip hypertension. In rabbits with two-kidney two-clip hypertension the plasma renin activity was significantly higher in the renal vein on the more involved side and comparable in the renal vein on the less involved side and the inferior caval vein. This response pattern of renin secretion, unilateral hypersecretion with contralateral suppression, was identical with that observed in animals with two-kidney one-clip hypertension. In animals with one-kidney one-clip hypertension there was a marked increase in plasma volume and blood urea nitrogen. The renovascular hypertension was in decreasing order of severity in animals with one-kidney one-clip hypertension, those with two-kidney two-clip hypertension and those with two-kidney one-clip hypertension.

Animals↗
PubMed1986

Autoregulation of renal blood flow in two-kidney, one-clip hypertensive rats.

Renal blood flow (RBF) autoregulation was examined in the clipped and nonclipped kidneys in two groups of two-kidney, one-clip (2K-1C) hypertensive rats 10 wk after clipping. The arterial pressure distal to the clip and the renin secretion rate (RSR) were also examined. The blood pressure (BP) was 149 +/- 4 and 162 +/- 6 mmHg in the two hypertensive groups vs. 114 +/- 3 mmHg in the controls (P less than 0.02). The RBF (in ml X min-1 X kidney-1) was 4.27 +/- 0.41 in the nonclipped and 2.18 +/- 0.23 in the clipped kidneys (P less than 0.001). The pressure distal to the clip was 104 +/- 7 mmHg. The renal vascular resistance (RVR) (in mmHg X ml-1 X min-1 X g-1) was 25.0 +/- 1.4 in the control kidneys vs. 58.4 +/- 4.5 in the nonclipped (P less than 0.001) and 39.9 +/- 6.6 in the clipped kidneys (P less than 0.01). The RBF autoregulation was well preserved in the nonclipped kidneys but reset to a higher lower pressure limit of autoregulation of 106 +/- 4 mmHg, which was significantly higher than in the normotensive controls (84 +/- 6 mmHg) (P less than 0.01). In the clipped kidneys there was complete loss of RBF autoregulation. RSR decreased with reduction of the perfusion pressure in the clipped kidneys. The increased RVR might have been due to a combination of structural and functional changes in both kidneys.

Animals↗
PubMed1986

Effect of ketanserin on pressor response to vasoactive substances in early phase of one-kidney, one clip renal artery stenosis in rats and rabbits.

The effect of ketanserin (KET), a specific 5-hydroxytryptamine2 (5-HT2) receptor blockade, on pressor response to vasoactive substances was examined in rats with one-kidney, one clip renal artery stenosis of 2 days' duration (2-day clipped rat) and in rabbits with renal artery stenosis of 3 days' duration (3-day clipped rabbits). The 2-day clipped rats showed hyperresponsiveness to norepinephrine (NE), arginine vasopressin (AVP) and 5-HT. All hyperresponsiveness were attenuated by a subdepressor dose of KET. The infusion of KET, 10 micrograms/kg/min for 30 minutes, decreased mean arterial pressure of the 3-day clipped rabbits; the dose did not alter blood pressure of the normal controls. Exaggerated pressor response to NE was observed in the 3-day clipped rabbits and was abolished by a subdepressor dose of KET, 2.5 micrograms/kg/min. These results suggest that 5-HT may be involved in the enhanced pressor response to vasoconstrictor substances in the 2-day clipped rats and 3-day clipped rabbits, and that it may also play an important role in maintaining blood pressure in the 3-day clipped rabbits.

Animals↗
PubMed1991

Laparoscopic clips. Evaluation of absorbable and titanium with regard to hemostasis and tissue reactivity.

Advanced laparoscopic techniques require laparoscopic means of providing hemostasis. We tested the hemostatic ability of laparoscopic surgical clips and their tissue reactivity as assessed by adhesion formation in an animal model. Twenty-six New Zealand white rabbits were randomized at laparotomy to one of three treatment groups: titanium surgical clips, absorbable surgical clips (both applied with a laparoscopic clip applicator) and chromic sutures of equal mass. Either the right fallopian tube was transected, with clips or sutures applied proximally and distally to control bleeding, or the clips or sutures were applied 5 mm apart and the tube transected. A clip or suture of the same material was placed on the midportion of the left fallopian tube. Necropsy was performed at 42 days, and each clip/suture site was scored for adhesions. All the materials were easily applied and effective in achieving hemostasis. The adhesion scores tended to be lower with the absorbable clips; however, there were no statistically significant differences between the groups. Laparoscopic clips are effective in providing hemostasis, are easily applied and cause no more adhesion formation than do conventional suture materials.

Animals↗
PubMed1987

Effects of verapamil and converting enzyme inhibition on bilateral renal function of two-kidney, one-clip hypertensive rats.

Experiments were conducted in two-kidney, one-clip renal vascular hypertensive rats (GHR) to assess the responses of each kidney to acute treatment with the antihypertensive calcium channel blocking agent verapamil in the presence and in the absence of converting enzyme inhibitor (CEI). One group of GHR (0.2 mm inner diam. clip 3 weeks before study) were examined during a control period, and during a second period of infusion of verapamil (600 micrograms h-1 kg-1). A second group of GHR were examined during a control period, during CEI (teprotide, 3 mg h-1 kg-1) infusion and during a third period of verapamil (600 micrograms h-1 kg-1) infusion superimposed on CEI infusion. Although systemic blood pressure (BP) decreased from 175 +/- 4 to 149 +/- 5 mmHg (mean +/- SEM) in response to verapamil alone, renal blood flow for non-clipped kidneys increased from 5.9 +/- 0.4 to 6.5 +/- 0.3 ml/min, indicating a 30% reduction of renal vascular resistance (P values less than or equal to 0.01; n = 9). Glomerular filtration rate (GFR) for non-clipped kidneys (n = 24) increased from 0.91 +/- 0.09 to 1.47 +/- 0.14 ml/min and filtration fraction increased from 0.32 +/- 0.04 to 0.47 +/- 0.03 (P values less than or equal to 0.05). Urine flow rate and absolute and fractional sodium excretion for non-clipped kidneys increased. GFR for clipped kidneys decreased during verapamil. Treatment with CEI alone resulted in nearly identical responses of BP and function of the non-clipped kidney, except filtration fraction was unchanged. The addition of verapamil to ongoing converting enzyme blockade tended to augment the increased GFR of the non-clipped kidney. Plasma renin activity (PRA) increased from 30 +/- 3 to 59 +/- 7 ng of angiotensin (ANG) I h-1 ml-1 with verapamil alone, a significantly larger increment than the increase of PRA from 27 +/- 5 to 39 +/- 9 ng of ANG I h-1 ml-1 in GHR subjected to comparable blood pressure reduction by mechanical aortic constriction. Verapamil resulted in many similar effects on renal function to those observed during blockade of converting enzyme. The increased filtration fraction observed in response to verapamil may be the result of vasodilatation of the afferent arteriole or of an increase in the glomerular ultrafiltration coefficient.

Angiotensin II↗
PubMed1988

Chronic angiotensin converting enzyme inhibition in the two-kidney, one clip hypertensive rat.

Treatment with an angiotensin converting enzyme (ACE) inhibitor in renovascular hypertension produces acute effects on renal function; however, the long-term consequences of this are not known. We have studied the effect of chronic enalapril treatment on renal structure and function in the two-kidney, one clip model of renovascular hypertension in the rat. Four weeks after the left renal artery was clipped, the hypertensive rats were randomly allocated to treatment with enalapril, minoxidil or to no treatment. The drug dose was titrated for maximal hypotensive effect. After 4 months of treatment blood pressures were 129 +/- 3 mmHg (enalapril), 193 +/- 5 mmHg (minoxidil) and 220 +/- 4.8 mmHg (no treatment). Twelve months later survival was 84% (enalapril group), 48% (minoxidil group) and 15% (untreated group). Split kidney function (51Cr-EDTA clearance, ml/min) of the clipped kidneys was 0.0 (enalapril group), 0.26 +/- 0.23 (minoxidil group) and 0.74 +/- 0.13 (untreated group). The clipped kidney from enalapril-treated rats weighed 0.46 +/- 0.1 g, much less than in the minoxidil-treated group (1.2 +/- 0.07) or the untreated group (1.14 +/- 0.10). Enalapril treatment was withdrawn for 2 weeks in five rats, but the clipped kidney remained small and non-functional. Histological examination revealed marked interstitial fibrosis and tubular atrophy in clipped kidneys from both enalapril groups, in contrast to minor changes in the minoxidil-treated and the untreated groups. We conclude that chronic enalapril treatment of two-kidney, one clip hypertension in the rat improved survival and preserved total renal function, but was associated with irreversible fibrotic atrophy of the clipped kidney.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

Renal atrial peptide receptors and natriuresis in two-kidney, one clip hypertension.

It has been suggested that the impaired natriuretic response of the clipped kidney in two-kidney, one clip hypertensive rats is related to downregulation of renal atrial natriuretic peptide receptors. To test this hypothesis, blood volume expansion and atrial peptide binding studies were performed in this model. Infusion of 1% and then 1.5% body weight donor blood (n = 6) caused a progressive increase in plasma immunoreactive atrial natriuretic peptide (107 +/- 26 to 168 +/- 31 to 427 +/- 154 pg/ml, p less than 0.001); the sodium excretion of the nonclipped kidney rose from 230 to 2,200 to 4,000 neq/min (p less than 0.01) but that of the clipped kidney did not rise significantly. There was a highly significant correlation between log cyclic guanosine monophosphate and log sodium excretion by the nonclipped (r2 = 0.749) but not the clipped (r2 = 0.046) kidney. Between clipped and nonclipped kidneys, the association constant (5.26 +/- 0.89 versus 5.17 +/- 0.64 x 10(9)/mol) and apparent binding site density (575 +/- 92 versus 500 +/- 74 fmol/mg protein) for atrial peptide binding in isolated glomeruli did not differ. Assay of atrial peptide-induced cyclic guanosine monophosphate release by isolated glomeruli showed that clipped and nonclipped kidneys were equally responsive. Binding affinity and receptor density did not differ in homogenates prepared from inner medullas of clipped and nonclipped kidneys. These results show that the blunted natriuretic response in clipped kidneys was not associated with any relative decrease in number or function of glomerular or papillary atrial natriuretic peptide receptors.

Animals↗
PubMed1989

Magnetic resonance imaging and aneurysm clips. Magnetic properties and image artifacts.

The magnetic properties of 12 different types of aneurysm clip were investigated in order to identify which clips allow postoperative magnetic resonance (MR) imaging without risk. Clip-induced MR artifacts were also quantitatively studied using a geometrical phantom. Nonferromagnetic aneurysm clips like the Yaşargil Phynox, Sugita Elgiloy, and Vari-Angle McFadden clips do not appear to contraindicate MR studies performed with a FONAR beta-3000M imager. There is no clip movement upon introduction of the phantom into the MR imager, and the image artifacts caused by the clips are so limited that patients harboring such clips may well be considered for MR imaging. This examination may reveal information not obtainable by any other radiological modality.

Aneurysm↗
PubMed1992

[An evaluation of temporary clipping during aneurysmal surgery: a retrospective study].

A temporary clipping of a parent artery has been found convenient in facilitating an aneurysmal dissection. This is because it controls the bleeding from an unexpected rupture and keeps the sac collapsed during the operation. Such a temporary arterial occlusion, however, involves the risk of a focal ischemia that may lead to permanent postoperative neurological deficits. Therefore, to evaluate the influence of a temporary clipping on the outcome of an operation, a retrospective study of 302 patients who underwent an operation for a ruptured supratentorial aneurysm between 1981 and 1990 has been conducted. This study has revealed the information that follows: 1) Overall outcomes In patients given no temporary clipping, their postoperative activity in daily living (ADL) grade was good in 70.7%, i.e. ADL 1 or 2, whereas only 46.4% of the patients given a temporary clipping achieved a similar ADL. 2) Influence of the preoperative Hunt and Kosnik neurological classification on the outcome Irrespective of whether a temporary clip had been used, patients with a Hunt and Kosnik grade of 1 or 2 made a good recovery, whereas patients with a grade of 4 or 5 did not. The application of a temporary clip in grade 3 patients led to a poor result, whereas in grade 3 patients given no temporary clipping the results were good. This would seem to indicate that Hunt and Kosnik grade 3 rating is a critical factor in consideration whether a temporary clip should be used or not. 3) Influence of the operative timing on the outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1988

Effects of bacterial infection on absorbable vascular ligating clips.

Electron microscopic observations of two implanted absorbable clips, Absolok and Lactomer, infected with Escherichia coli and Streptococcus faecalis, were carried out. An overgrowth of bacteria was observed over the entire surface of the clips. The mating surfaces of the Lactomer clips and the locking mechanisms of both types of clip were more heavily infected--that is, provided better support for bacterial growth--than other areas of the clips in the initial postimplantation period. However, with longer periods (up to seven days), the initial bacterial deposits developed into a thick, plaquelike layer. This layer appeared to restrict access to the surfaces such that the infected clips degraded at a much slower rate than did the noninfected clips, particularly Lactomer clips, on which little morphologic change was detectable seven days after implantation.

Animals↗
PubMed1988

Tissue reactions to absorbable ligating clips.

Scanning electron microscopy was used in a comparative ultrastructural study of biodegradable ligating clips, the Absolok (polydioxanone) and the Lactomer (copolymer of glycolic and lactic acids), implanted subcutaneously in rabbits. The inflammatory response and tissue reactions to the implanted clips and their effects on clip breakdown were studied. By the first week after implantation, numerous inflammatory cells adhered to the clip surfaces, with occasional fibroblasts present. By two weeks after implantation there was a reduction in the number of inflammatory cells, but the number of fibroblasts gradually increased, resulting in encapsulation of the clips. The thickness of the fibrous tissue capsule, formed by a variety of collagen fibers, gradually increased 5-25 weeks after implantation. Residues from the Lactomer clips were still present within the encapsulating tissue at 25 weeks. In contrast, clips enclosed in nylon pouches were totally degraded, and no residues were detectable at 25 weeks. Tissue reactions similar to those observed for nonpouched implanted clips were seen over the entire external surface of the pouches.

Animals↗
PubMed1987

Study of renovascular hypertension in rats. IV. Renal arterial blood velocity in one-clip, two-kidney hypertensive rats.

In one-clip, two-kidney hypertensive models of rats, the renal arterial blood velocity was recorded using the bidirectional Doppler velocimeter before and at various times after clipping of the renal arteries. In all the rats, immediately after placement of a clip, the blood velocity of the stenosed artery was lowered significantly. Although the blood velocity remained low 2 weeks after clipping, it recovered to the pre-clip level at 6 and at 11 to 13 weeks after clipping. The plasma renin activity tended to decrease following the acute, high-renin stage of hypertension. If it can be assumed that the blood velocity is one of the indexes representing blood flow, its return to the pre-clip normal level in the chronic stage of renovascular hypertension may signify recovery of blood flow to the clipped kidney leading to a reduction in renal renin synthesis and consequently a decrease in plasma renin activity.

Animals↗
PubMed1979

Laparoscopic sterilization with the spring clip: instrumentation development and current clinical experience.

Since the original spring clip sterilization studies were reported, a number of clinically important modifications to the spring clip and applicator have been developed. The spring-loaded clip, manufactured by Richard Wolf Medical Instruments Corporation of Chicago, Illinois, and Rocket of London, Inc., London, England, and New York, New York can be applied with either a one- or two-incision applicator and the clips and applicators currently available incorporate improvements to the original prototypes in design, manufacture, and quality control. The two-incision applicator is associated with significantly fewer misapplications and the high pregnancy rates reported with the original clip and applicator have not occurred with the current designs. Comparative studies between the clip and band have revealed less operative bleeding and pain associated with the clip. The method is appropriate to all women requesting sterilization but especially to those in the younger age group who may subsequently request reversal because of divorce and remarriage.

Female↗
PubMed1977

Vas occlusion by tantalum clips and its comparison with conventional vasectomy in man: reliability, reversibility, and complications.

Occlusion of the vas deferens has been carried out by applying tantalum clips in 60 men. Another 50 men were vasectomized conventionally and served as controls. Vasography showed that two clips were required on each vas to bring about perfect and firm occlusion. The incidence of postoperative infection and other complications was much lower in the clip-occluded cases. Under a long-term follow-up, 10% of the conventionally vasectomized men were dissatisfied with the operation as compared with 2% of the clip-occluded group. Both groups became azoospermic within 3 months and the failure rate was zero. Removal of the clips not only was difficult but left the vas compressed and leaking. The method cannot, therefore, be considered reversible by itself. However, recanalization could easily be achieved by end-to-end anastomosis after excision of the small clipped segment or by side-to-side anastomosis without any excision. This, damage to the neuromuscular apparatus of the vas may be minimized. Male sterilization by clip occlusion has the advantages of minimal surgical intervention, shorter operative time, safety from postoperative infection, and easier recanalization if desired.

Evaluation Studies as Topic↗
PubMed1978

Structural changes in the human vas deferens after tantalum clip occlusion and conventional vasectomy.

In 15 human subjects, the vasa deferentia were occluded by applying two tantalum clips on one side and by conventional vasectomy with silk ligatures on the other. After 2 weeks, the occluded segments were recovered for histopathologic examination of serial sections. Obstructing the seminal tract did not, as such, produce any significant change in the vas: the distal and proximal segments appeared to be essentially similar and normal. At the actual site of occlusion, however, tantalum clips produced marked flattening of the tube, complete loss of lining epithelium, distortion of the muscular lamellae, and areas of hemorrhage. The lumen was converted into a narrow slit. Under the ligatures, the damage was largely confined to denudation of the mucosal epithelium. The mucosa of the intersegment left unexcised between two clips showed hyalinization, invasion by macrophages, and degeneration of the epithelium. The changes under the clips suggest that, although clip occlusion may offer several advantages, sterility cannot be reversed merely by removing the clips. The mechanisms of these changes, different in the case of clips and ligatures, are discussed and some possible long-term consequences are considered.

Epididymis↗
PubMed1986

Effects of antihypertensive treatment in one-clip, two kidney hypertension in rats.

In order to investigate the consequences of antihypertensive therapy on hormonal and renal parameters in one-clip, two kidney renovascular hypertension, we compared the effects of converting enzyme inhibition (CEI) with those of tripletherapy (clonidine, dihydralazine and furosemide) in this experimental model in rats. The treatment period was initiated four weeks after application of the clip and was continued for five weeks. In plasma, renin was increased and renin substrate was negatively correlated to plasma renin. Hypertension was associated with activation of the renin angiotensin system in both plasma and kidney. The degree of activation of the renin-angiotensin system in the clipped kidney and its suppression in the unclipped kidney was evaluated by two methods, renal renin content and semi-quantification of juxtaglomerular hyperplasia by immunofluorescent renin. These two methods were correlated. During the treatment period, average systolic blood pressure was 144 +/- 13 mmHg in the CEI treated group (HT1) which was not significantly different from the value found in the sham-operated group (139 +/- 4 mmHg; C2). Blood pressure, however, was lowered only to 173 +/- 18 mmHg in the group treated with tripletherapy (HT2). In control hypertensive animals, the wt of the clipped kidney did not decrease whereas significant hypertrophy was present in the unclipped kidney. Tripletherapy did not alter this relationship, whereas converting enzyme inhibition decreased kidney wt in the clipped kidney and increased further the hypertrophy of the contralateral unclipped kidney. A histological examination revealed that hypertensive microangiopathy was a predominant feature in the unclipped kidney of the untreated hypertensive group and of the group treated with tripletherapy, these lesions were completely absent in the CEI treated group. In the CEI treated group, however, ischemic lesions during this treatment were found to be decreased in the contralateral unclipped kidney and increased in the clipped kidney by comparison with untreated hypertensive rats. These renal lesions observed in the clipped kidney were most likely related to the normalization of blood pressure or to a disturbance of intrarenal mechanisms normally mediated by the renin-angiotensin system during stenosis of a renal artery.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Surgical and electrophysiological observations during clipping of 134 aneurysms with evoked potential monitoring.

Somatosensory evoked potentials (SEPs) were monitored during 113 operations for the clipping of 134 cerebral aneurysms. Changes in peak latency and amplitude of early cortical SEP as well as central conduction time were evaluated. In 58 cases surgical occlusion of arterial vessels or other events occurred, and in 17 of these cases such events were associated with SEP changes or loss. Arterial occlusions resulted from temporary clipping of a feeding blood vessel (22), accidental clipping of a vessel (12), and intentional permanent vessel occlusion (8). A total SEP loss was seen in 2 cases of accidental vessel occlusion and in 6 cases of temporary vessel clipping. Significant SEP changes were found in 6 patients with temporary clipping, and once each with retraction of the cerebellum, retraction of the middle cerebral artery, and after intentional permanent vessel occlusion. Response to these changes included reapplication of aneurysm clips, repositioning of retractors, or removal of temporary clips. Stable SEP signals during 13 cases allowed the surgeon to proceed with the surgical course. Despite the limitations of SEP monitoring in certain anatomical locations, it has been found to be helpful in the operative management of some cases such as multilobed aneurysms of the middle cerebral artery, giant aneurysms, trapping procedures, and procedures requiring temporary vessel occlusion.

Adolescent↗
PubMed1990

A comparative study in opening and closing pressures of cerebral aneurysm clips.

Modern aneurysm clips with newer metallurgic properties and state-of-the-art designs have evolved through the years. Regretfully, manufacturers are still not required to provide product information regarding clip strength, and when such information is supplied, there is no interbrand consistency to how it is obtained. This experiment compares the closing pressures of 5 commonly used brands of aneurysm clips: Yasargil, Sugita, Sundt-Kees, Vari-Angle McFadden, and Heifetz. Interclip comparison is also made of opening pressures, that is, the arterial pressure required to open an aneurysm clip. Findings show a distinct difference in closing forces among these brands of aneurysm clips. The study of opening forces indicates that the important factors determining clip release or displacement were the failure of the clip to cross the vessel completely and intrinsic characteristics of the vascular wall.

Constriction↗