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PubMed1990

Baroreceptor-heart rate reflex function before and after surgical reversal of two-kidney, one-clip hypertension in the rat.

Baroreflex function was studied in conscious early phase (less than 6 weeks) two-kidney, one-clip hypertensive rats before and 24 hours after surgical reversal of hypertension by removal of the constricting renal artery clip or after pharmacological reduction of blood pressure by an infusion of hydralazine or captopril. A normotensive sham-clipped group was included. Another group of two-kidney, one-clip rats was studied 3 weeks after unclipping. Baroreflex sensitivity, as assessed by the steady-state method using a graded phenylephrine infusion, mean arterial pressure, and heart rate were measured preoperatively and at 24 hours postoperatively. Two-kidney, one-clip rats were significantly hypertensive preoperatively compared with control (mean arterial pressure, 183 +/- 4 vs. 106 +/- 2 mm Hg, p less than 0.001), heart rate was similar (420 +/- 9 vs. 401 +/- 9 beats/min, p greater than 0.05), and baroreflex sensitivity was significantly reduced (0.76 +/- 0.07 vs. 1.50 +/- 0.20 msec/mm Hg; p less than 0.001). There was a minimal change in heart rate despite the fall in mean arterial pressure in all hypertensive groups, indicating resetting of the baroreflexes. At 24 hours after the operation, baroreflex sensitivity was unchanged in all groups compared with the preoperative value. By 3 weeks, baroreflex sensitivity was significantly greater than in the hypertensive two-kidney, one-clip rats before the operation and 24 hours after they were unclipped, but not compared with normotensive sham-clipped rats. Thus, although resetting occurs within 24 hours, whatever the method of blood pressure reduction, baroreflex sensitivity remains impaired at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1978

Interrelationship of aneurysm clips and vascular tissue.

Various straight-jawed aneurysm clips were tested for occluding capabilities on a vascular tissue model. Occluding pressures varied markedly among the clip styles and were altered by changes in the lumen and tissue composition of the model. Mechanical characteristics are highly variable between clip styles, but fall within a narrow range for clips of a similar style. The complex interplay of the unique aspects of clip design and force generated by the spring in conjunction with tissue characteristics and precise clip placement upon the tissue are major variables in the apparent ability of a particular clip to occlude the neck of an aneurysm.

Animals↗

PubMedDate not supplied

A comparison of the clip and ring techniques for laparoscopic sterilization of postabortion and postpartum patients.

The spring-loaded clip and the tubal ring techniques of laparoscopic female sterilization are compared for ease of performance, safety and effectiveness at the Kandang Kerbau Hospital in Singapore. The two techniques were randomly assigned to 299 postpartum patients and 300 postabortion patients. The assigned procedure could not be performed for two of the ring cases and three of the clip cases. Bleeding and equipment problems made laparotomy necessary in two clip cases and equipment problems caused a change in technique in the other clip case. Hydrosalpinx and adhesions were responsible for a change to laparotomy in the two ring cases. Surgical difficulties, chiefly the result of equipment problems, were significantly higher for both postpartum and postabortion clip procedures. Complications and complaints reported immediately after surgery and at the 7- to 21-day follow-up visit were low for all four groups. For both postabortion and postpartum patients, six- and 12-month data show that pregnancy rates are significantly higher for patients sterilized with the clip than with tubal rings.

Abortion, Induced↗

PubMed1990

Tissue reactivity and degradation patterns of absorbable vascular ligating clips implanted in peritoneum and rectus fascia.

Absorbable vascular ligating clips are finding increasing use in intraabdominal surgery. We report the results of a light and scanning electron microscope investigation of the tissue reactivity and clip degradation patterns of two such materials, Absolok (polydioxanone) and Lactomer (copolymer of glycolic and lactic acid), implanted in the fascia and peritoneum of rabbits for intervals of 2 to 70 days. Cellular response to the clips, defined as the number of inflammatory cells/10(4) microns 2, was maximum at day 4 postimplantation, then gradually declined as the duration of implantation increased. This pattern, seen with both types of clips, was similar to that seen with polydioxanone (PDS) suture, but significantly greater than that associated with polypropylene (Prolene) suture. Although cellular response to the clips was greater in peritoneum than in fascia, especially on two occasions associated with adhesion formation, this was not statistically significant. Based on our morphological observations, the signs of clip degradation which were indicated by the appearance of surface crazing and cracks occurred earlier in peritoneum than in fascia.

Abdomen↗

PubMed1989

Safety of metallic surgical clips in patients undergoing high-field-strength magnetic resonance imaging.

Use of metallic clips with ferromagnetic properties in patients undergoing a large variety of surgical procedures, and in particular, in coronary artery and other vascular reconstructions, has become increasingly popular. The safety of these commonly used surgical clips when subjected to high-intensity diagnostic magnetic resonance imaging fields is still debated. Commonly used hemostatic metallic clips manufactured by the Weck and US Surgical Corporations were tested in an in vitro system to assess their safety with regard to migration and displacement. The two tested hemostatic metallic clips proved safe and did not migrate or become dislodged when they underwent magnetic resonance imaging scans. This is in direct contrast to multiple cerebral aneurysm clips, also tested, which have highly ferromagnetic properties and were previously shown to migrate with disastrous results in patients undergoing diagnostic magnetic resonance imaging scans. This study supports the continued widespread use of small metallic hemostatic clips in the myriad of procedures in which they are presently used and illustrates the need for methods of evaluating such devices before they are clinically implanted.

Electromagnetic Fields↗

PubMed1992

CLIP-170 links endocytic vesicles to microtubules.

Binding of endocytic carrier vesicles to microtubules depends on the microtubule-binding protein CLIP-170 in vitro. In vivo, CLIP-170 colocalizes with a subset of transferrin receptor-positive endocytic structures and, more extensively, with endosomal tubules induced by brefeldin A. The structure of CLIP-170 has been analyzed by cloning its cDNA. The predicted non-helical C- and N-terminal domains of the homodimeric protein are connected by a long coiled-coil domain. We have identified a novel motif present in a tandem repeat in the N-terminal domain of CLIP-170 that is involved in binding to microtubules. This motif is also found in the Drosophila Glued and yeast BIK1 proteins. These features, together with its very elongated structure, suggest that CLIP-170 belongs to a novel class of proteins, cytoplasmic linker proteins (CLIPs), mediating interactions of organelles with microtubules.

Amino Acid Sequence↗

PubMed1988

Atrial natriuretic factor: specific binding to renal glomeruli during the development of two-kidney, one clip hypertension in the rat.

Blood pressure (BP), atrial and plasma concentrations of atrial natriuretic factor (ANF), hematocrit and renal glomerular ANF receptors were studied during the development of hypertension in two-kidney, one clip (2-K, 1C) rats and were compared with normotensive controls. Plasma ANF was elevated in the 2-K, 1C group in all stages of hypertension, even after 3 weeks when BP, although higher than in sham-operated animals, had not yet reached arbitrarily-set hypertensive levels. At this time, hematocrit was higher in the hypertensive rats than in the controls, but the difference later disappeared. Lower atrial ANF concentrations were observed in the 2-K, 1C group at week 3, but only in the right atrium. No difference in ANF levels was noted in either the left or right atrium between hypertensive and normotensive animals 5 and 7 weeks after clipping. The glomerular ANF receptor population was markedly smaller in the clipped left kidney of 2-K, 1C rats during all stages of hypertension, and in the untouched right kidney at 5 and 7 weeks after surgery, but was larger in the non-clipped right kidney in the pre-hypertensive phase (3 weeks). It is concluded that receptor density changes during the evolution of high BP in the 2-K, 1C Goldblatt model of experimental hypertension. Our data suggest that the increases and decreases in density of renal glomerular ANF receptors may play a role in the differential handling of sodium by the clipped and non-clipped kidney during the various stages of development of 2-K, 1C hypertension in the rat.

Animals↗

PubMed1991

Imaging properties of polydioxanone and titanium ligating clips following para-aortic lymphadenectomy for testicular cancer.

Stainless steel ligating clips produce serious artefacts on CT scans. Polydioxanone (PDS) and titanium ligating clips were used in 15 patients during para-aortic lymphadenectomy for residual metastatic testicular teratoma following chemotherapy, and follow-up CT images were compared with those following the use of stainless steel ligating clips. PDS ligating clips did not produce any artefacts and were progressively absorbed. Titanium ligating clips produced artefacts similar to but less intense than those of stainless steel. PDS ligating clips should be used when follow-up CT scanning is important.

Constriction↗

PubMed1989

Body fluid volume and angiotensin II in maintenance of one-kidney, one clip hypertension.

To investigate the possible role of body fluid volume or the renin-angiotensin system in the maintenance of high blood pressure in chronic one-kidney, one clip (1K1C) hypertension, we studied whether blood pressure remained high after removal of the clip while the body fluid volume was kept constant or when angiotensin II (Ang II) was infused in conscious 1K1C rats. Blood pressure fell 58 +/- 13 mm Hg in 1K1C rats after removal of the clip. When body fluid volume was kept at the same level as before "unclipping," blood pressure fell only 9 +/- 2 mm Hg after removal of the clip; if body fluid volume was then allowed to decrease, blood pressure fell an additional 55 +/- 8 mm Hg. When Ang II was infused after removal of the clip, blood pressure fell 26 +/- 7 mm Hg despite the fact that plasma Ang II increased to nonphysiological concentrations (1,161 +/- 353 pg/ml). After Ang II infusion was stopped, blood pressure fell an additional 44 +/- 13 mm Hg. When Ang II was infused and body fluid volume kept constant, blood pressure still did not change after removal of the clip, although plasma Ang II concentrations increased to nonphysiological levels (618 +/- 98 pg/ml). After the Ang II infusion was discontinued and the body fluid volume was no longer kept constant, blood pressure fell 78 +/- 9 mm Hg. These data further support the hypothesis that a volume factor, not the renin-angiotensin system, is important in the maintenance of high blood pressure in 1K1C hypertension.

Angiotensin II↗

PubMed1989

Impaired renorenal reflexes in two-kidney, one clip hypertensive rats.

In normotensive rats, stimulation of renal mechanoreceptors by an increase in ureteral pressure results in a contralateral inhibitory renorenal reflex response with contralateral natriuresis. Similar effects are produced by stimulation of renal chemoreceptors by renal pelvic perfusion with 0.9 M NaCl. However, in spontaneously hypertensive rats the renorenal reflex responses to renal mechanoreceptor and chemoreceptor stimulation are impaired. The present study was performed to examine whether the renorenal reflexes were altered in two-kidney, one clip hypertensive rats, a model of hypertension in which it has been suggested that the afferent renal nerves contribute to the enhanced peripheral sympathetic nervous activity. A 0.2 mm silver clip was placed around one renal artery 4 weeks before the study. At the time of study, mean arterial pressure was 156 +/- 4 mm Hg. Renal mechanoreceptor and chemoreceptor stimulation of either the nonclipped or clipped kidney failed to affect ipsilateral afferent renal nerve activity, contralateral efferent renal nerve activity, and contralateral urine flow rate and urinary sodium excretion. Renal denervation of the nonclipped kidney increased ipsilateral urinary sodium excretion from 0.65 +/- 0.13 to 1.50 +/- 0.42 mumol/min/g and decreased contralateral urinary sodium excretion from 0.18 +/- 0.03 to 0.13 +/- 0.03 mumol/min/g (p less than 0.05). Thus, denervation of the nonclipped kidney resulted in a similar contralateral excitatory renorenal reflex response as in normotensive rats. However, denervation of the clipped kidney increased both ipsilateral and contralateral urinary sodium excretion, from 0.14 +/- 0.04 to 0.27 +/- 0.5 mumol/min/g and from 1.29 +/- 0.33 to 2.09 +/- 0.59 mumol/min/g (p less than 0.01), respectively. Taken together these data suggest that the lack of inhibitory renorenal reflexes from the clipped kidney may enhance efferent sympathetic nervous activity and thereby contribute to the hypertension in two-kidney, one clip hypertensive rats.

Animals↗

PubMed1992

Increased vascular formation of angiotensin II in one-kidney, one clip hypertension.

To assess the role of the vascular angiotensin II-generating system in one-kidney, one clip hypertension, we determined the angiotensin converting enzyme activity in plasma and vascular tissues and examined the pressor response to angiotensin II, angiotensin I, and tetradecapeptide renin substrate in isolated mesenteric arteries from one-kidney, one clip hypertensive rats 7 and 30 days after clipping the renal artery and in mesenteric arteries from age-matched normotensive rats. Angiotensin converting enzyme activity, determined in aortic and mesenteric tissues, was significantly augmented in the hypertensive (30 days after clipping) group, whereas plasma activity was normal. The vasoconstrictor responses elicited by angiotensin I and tetradecapeptide in arteries from hypertensive rats were found to be significantly potentiated 30 days after clipping, whereas the angiotensin II responses were basically unchanged. Saralasin completely blocked the vasoconstrictor responses, whereas captopril blocked only the responses to angiotensin I without affecting the responses elicited by angiotensin II and tetradecapeptide. Enalapril, an angiotensin converting enzyme inhibitor given intravenously to unanesthetized rats, significantly lowered the blood pressure of hypertensive rats. The pressor responses elicited by angiotensin II, angiotensin I, and tetradecapeptide were completely inhibited by saralasin, whereas enalapril blocked only the responses of angiotensin I but not those elicited by angiotensin II and tetradecapeptide. These results indicate that local formation of angiotensin II is increased in arteries of one-kidney, one clip hypertensive rats. The data obtained with tetradecapeptide renin substrate suggest an important role for nonrenin proteases in vascular angiotensin II formation.

Angiotensin I↗

PubMed1992

Angiotensin and angiotensin converting enzyme tissue levels in two-kidney, one clip hypertensive rats.

Renal tissue angiotensin I (Ang I) and II (Ang II) content and angiotensin converting enzyme activity were assessed in both kidneys during initial (7 days) and maintenance (25 days) phases of two-kidney, one clip hypertension in rats. At 7 and 25 days, systolic arterial pressure was 146 +/- 2 and 170 +/- 7 mm Hg, respectively. After 7 days, Ang I content of clipped kidneys was 64% and 70% higher (p < 0.001) than in nonclipped and sham-operated kidneys, respectively, when compared with levels in kidneys from sham-operated rats. In kidneys harvested 25 days after clipping one renal artery, Ang I and Ang II contents in clipped kidneys were increased 102% and 24% (p < 0.01), respectively. Ang II content was also 32% higher in nonclipped kidneys. Angiotensin converting enzyme activity in nonclipped kidneys was greater (p < 0.05) than that in either clipped (46% higher) or sham-operated kidneys (57% higher). Plasma Ang I and Ang II levels were elevated at 7 days but were not different at 25 days in clipped rats. These results demonstrate a dissociation between intrarenal and circulating levels of Ang I and Ang II and suggest that qualitatively different mechanisms may be responsible for the elevated intrarenal Ang II levels during the initial and maintenance phases of renal hypertension.

Angiotensin I↗

PubMed1989

[Recurrent cerebral aneurysm suggestive of misplaced clipping. Case report].

A case of recurrent cerebral aneurysm after complete neck clipping is described. A 47-year-old male who presented with headache and nausea underwent neck clipping of a berry aneurysm of the left middle cerebral artery. Ten days later, angiographic findings suggested the presence of a second, large aneurysm adjacent to the first, which suggested misplaced clipping. Reoperation confirmed that a new aneurysm had formed next to the original aneurysm. A possible explanation of the recurrence is as follows. The M1 flowed into the M2 at a right angle. The aneurysmal neck was situated on the distal end of the M1 and the dome protruded antero-inferiorly at an angle of nearly 90 degrees to the long axis of the M1 opposite the origin of the M2. The parent artery bulged slightly, and its wall was thin and reddish, just distal to the aneurysmal neck. Proximal to the neck there was another small bulge, but the wall here was normal. These bulges were coated with Oxycel and Biobond at the time of aneurysmal neck clipping. After clipping, blood flow into the dome was interrupted, and the consequent hemodynamic stress caused the bulges to expand dramatically and form a new aneurysm. The authors conclude that there is a likelihood of early recurrence after neck clipping if the parent artery exhibits such morphological features as observed in this case.

Cerebral Arteries↗

PubMed1979

Endothelial lesions after temporary clipping. A comparative study.

The effect of temporary clipping on the arterial endothelium of rats was examined with scanning electron microscopy. The opening pressure of four Heifetz clips was modified by changing the springs. Four different clip forces (20, 35, 45, and 65 gm), four periods of clipping (10, 30, 60, and 180 minutes), and three vessel diameters (smaller than 1 mm, 1.1 to 1.3 mm, and 1.4 to 2 mm) were compared. Different grades of endothelial damage were observed. On gross examination the damage involved a detachment of endothelium and the adherence of platelets to the subendothelial tissue. The duration of clipping seemed to be of more importance than the clip force, whereas the vessel diameter had no recognizable influence.

Animals↗

PubMedDate not supplied

A monoclonal antibody directed against CLIP (ACTH 18-39). Anatomical distribution of immunoreactivity in the rat brain and hypophysis with quantification of the hypothalamic cell group.

After the recent demonstration of the facilitatory effect exerted by corticotropin-like intermediate lobe peptide (CLIP or adrenocorticotropic hormone (ACTH) 18-39) on paradoxical sleep in the rat (Chastrette and Cespuglio, 1985), we undertook the production of monoclonal antibodies against this peptide. Wistar rats were immunized against CLIP and their spleen cells fused with mouse myeloma cells. After recloning, 25 supernatants were found to give positive immunohistochemical reactions in the rat brain. In immunohistochemical tests performed by preabsorption, the 25 supernatants presented similar properties, i.e. recognized CLIP, ACTH (1-39) and ACTH (25-39), but not ACTH (1-24) and the C-terminal fragment (34-39). We assume that the epitope(s) recognized by the 25 supernatants is (are) located between the amino-acids Asn25 and Ala34 of the CLIP molecule. The immunoreactivity observed in the rat brain and hypophysis with this antibody was distributed with a pattern quite similar to that described for anti-ACTH antibodies. A main group of immunoreactive cell bodies was located in the mediobasal hypothalamus and a small group in the nucleus of the solitary tract. Immunoreactive fibres were distributed from the olfactory nucleus to the spinal cord and formed particularly rich networks in the hypothalamus and preoptic area. Among other locations, immunoreactive axons were also present in the brainstem centres involved in the control of the sleep-waking cycle, which is in accordance with the influence of CLIP on paradoxical sleep. Using Abercrombie's formula, the number of immunoreactive cells in the mediobasal hypothalamus was estimated at about 3000 neurons. We conclude that our monoclonal anti-CLIP antibody can be considered as a good marker of proopiomelanocortin neurons.

Adrenocorticotropic Hormone↗

PubMed1987

Chronic administration of ketanserin and the development of two-kidney-two-clip Goldblatt renovascular hypertension in the rat.

The effect of ketanserin (Kt) has been analyzed during the development of two-kidney-two-clip (2k-2c) renovascular hypertension in the rat. Male Wistar rats were divided into four experimental groups: (1) clip Kt (ClKt) (n = 12)--A silver clip (0.25 mm width) was placed in each renal artery 3 days after beginning the administration of Kt (10 mg/kg/day) in the drinking water; (2) sham Kt (ShKt) (n = 13)--Similar to group 1, but the clips were placed in, and immediately removed from, the renal arteries; (3) untreated clip (UCl) (n = 10)--Similar to group 1, but the rats drank water; (4) untreated sham (USh) (n = 10)--Similar to group 2, but the rats drank water. Blood pressure (BP) was measured before surgery and was followed weekly for 7 weeks. At the end of this period, blood and cerebrospinal fluid (CSF) samples were obtained in all the animals. Plasma renin activity (PRA) and plasma and CSF angiotensinogen concentration (AoC) were evaluated. The results have shown that Kt partially inhibited the increase in BP induced by bilateral renal ischemia (BP: UCl rats 180.5 +/- 12.4 versus ClKt rats 149.8 +/- 5.1 mm Hg; p less than 0.01; USh rats 116.7 +/- 3.7; ShKt rats 114.4 +/- 5.0 mm Hg). PRA was similar in hypertensive and control rats whether or not they had received Kt. AoC in plasma was decreased in clipped treated and untreated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensinogen↗

PubMed1989

[A case of ruptured middle cerebral artery aneurysm with acute subdural hematoma after clipping of the aneurysm nine years previously].

It is known well that acute subdural hematoma develops most frequently after head injury, and secondly from pathological lesions such as intracranial ruptured aneurysm or AVM. A case of ruptured middle cerebral artery aneurysm which was clipped nine years before resulting in acute subdural hematoma is reported. At 6 pm on July 21, 1988, a 53-year-old woman with severe headache starting at 4:20 pm was transferred to our hospital. She suffered from herniated signs; Conscious disturbance; anisocoria; positive OCR; decerebrate posture. An emergency CT showed right acute subdural hematoma with severe midline shift. Following a decompressing craniotomy at 9 pm, the subdural clot was evacuated. It measured 90g in volume and the underlying cortex was normal. There was no evidence of SAH. Right carotid angiography three weeks after the first operation showed a middle cerebral artery aneurysm at the site of a clip which had been applied nine years ago. A second operation was performed on August 30, 1988. Via the right pterional route, the middle cerebral artery aneurysm was clipped successfully with a Sugita's clip replacing the first clip. We concluded that the regrowth and rebleeding of the middle cerebral artery aneurysm which had been clipped nine years before was most probable. She was discharged with slightly decreased consciousness and right motor weakness, on November 13, 1988.

Acute Disease↗

PubMed1977

A comparative study of spring-loaded clips and electrocoagulation for female sterilization.

The surgical, immediately postoperative and delayed postoperative complications and complaints associated with spring-loaded clips and electrocoagulation as techniques of tubal sterilization at laparoscopy were evaluated in a comparative study. Each of the two techniques was randomly assigned to 150 subjects. All sterilizations were performed as outpatient procedures. Subjects were followed-up during the first six weeks and again at about six months after sterilization. Rates of complications (surgical and early postoperative) were similar for the two procedures. None of the subjects required subsequent hospitalization. Technical difficulties at surgery were more frequent with the spring-loaded clip technique, principally as a result of mechnical problems with the prototype laparoscope and clip applicator. Postoperative pelvic and abdominal pain were reported by a significantly higher proportion of the patients when the spring-loaded clip was used (spring-loaded clips, 43.6%; electrocoagulation, 31.5%). At the six-month follow-up examination, rates of abnormal pelvic findings and changes in menstrual cycle formation were similar for the two techniques of tubal occlusion. There was one procedure failure among the electrocoagulation patients and none among the spring-loaded clip patients.

Adult↗