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Rac1 and Cdc42 capture microtubules through IQGAP1 and CLIP-170.

Linkage of microtubules to special cortical regions is essential for cell polarization. CLIP-170 binds to the growing ends of microtubules and plays pivotal roles in orientation. We have found that IQGAP1, an effector of Rac1 and Cdc42, interacts with CLIP-170. In Vero fibroblasts, IQGAP1 localizes at the polarized leading edge. Expression of carboxy-terminal fragment of IQGAP1, which includes the CLIP-170 binding region, delocalizes GFP-CLIP-170 from the tips of microtubules and alters the microtubule array. Activated Rac1/Cdc42, IQGAP1, and CLIP-170 form a tripartite complex. Furthermore, expression of an IQGAP1 mutant defective in Rac1/Cdc42 binding induces multiple leading edges. These results indicate that Rac1/Cdc42 marks special cortical spots where the IQGAP1 and CLIP-170 complex is targeted, leading to a polarized microtubule array and cell polarization.

Actins↗

The CLIP-substituted invariant chain efficiently targets an antigenic peptide to HLA class II pathway in L cells.

The presentation of antigenic peptides by major histocompatibility complex (MHC) class II to CD4+ T cells is crucial to initiate immune responses. We developed a new system for delivery of an antigenic peptide to the MHC class II pathway, using the invariant chain (Ii). We designed a mutated human p33-form Ii, CLIP-substituted Ii, in which streptococcal M12p55-68 (RDLEQAYNELSGEA) was substituted for CLIP (class II associated invariant chain peptide). We examined the peptide presenting function of this construct, in comparison with the previously reported C-terminal fused Ii, in which a cathepsin cleavage site and M12p54-68 was ligated to the C-terminus of Ii. Mouse L cell transfectants expressing either of these two mutated Ii along with HLA-DR4 could process and present M12p55-68 to the peptide specific and DR4-restricted CD4+ T cell clone. CLIP-substituted Ii was much more efficient in antigen presentation than was the C-terminal fused Ii. Similar to the wild-type Ii, the CLIP-substituted Ii was associated intracellularly with DR4 molecules. These results indicate that the peptide substituted for CLIP of Ii p33 bound to the groove of DR molecules in the same manner as CLIP and it was preferentially presented to the CD4+ T cell clone in the absence of HLA-DM molecules. This system may prove useful for immunotherapy with DNA vaccines or for construction of an antigen presenting cell library with diverse peptides.

Amino Acid Sequence↗

Arterial and venous repair with vascular clips: comparison with suture closure.

PURPOSE: Nonpenetrating, arcuate-legged titanium vascular closure staple (VCS) clips were initially developed for microvascular anastomoses with little experience of their use in larger vessels. The purpose of this study was to compare the VCS clips with standard suture closure of arteriotomies and venotomies in common iliac vessels of pigs. METHODS: In nine pigs, longitudinal 1 cm iliac arterial and venous incisions were repaired with VCS clips on one side and continuous 6-0 polypropylene suture on the other, and the macroscopic and microscopic results were assessed after 3 months. RESULTS: The time required for vessel repair was significantly shorter with clips than with sutures both in arteries (51 +/- 9 vs 414 +/- 36 seconds) and in veins (100 +/- 32 vs 439 +/- 45 seconds). There was no significant difference in the inner diameter, intimal thickness, or intima-to-media height ratios of the arteries or veins after either method of closure. CONCLUSIONS: Repair of 1 cm incisions in small-diameter arteries and veins with VCS clips results in wound healing as good as that achieved with standard suture closure, when assessed for patency, leakage, degree of narrowing, and intimal reaction. The time required for clip closure is considerably shorter than for suture closure.

Animals↗

Preparation of a spermine conjugate of the bis-phenanthroline ligand Clip-Phen and evaluation of the corresponding copper complex.

We described the synthesis of conjugates of N, N-diethylethylenediamine and spermine with Clip-Phen, a new ligand with two 1,10-phenanthrolines linked by serinol. The ability of the copper complexes of these Clip-Phen conjugates to cleave PhiX174 DNA when activated by a reductant in the presence of air was compared to that of 1,10-phenanthroline copper complexes. The results indicated that Clip-Phen-spermine with copper was the most active DNA cleaver. Comparison with a conjugate having only one phenanthroline unit linked to spermine showed that the high activity of Clip-Phen-spermine-Cu was not only due to the presence of spermine, which increases the affinity of the Clip-Phen entity for the DNA, but was effectively due to the presence of the two bridged phenanthroline entities. The DNA cleavage activity of (Clip-Phen-spermine)CuCl2 was analyzed on a 167 bp restriction fragment and a 45-mer double-stranded oligonucleotide.

Bacteriophage phi X 174↗

Upregulation of the CLIP self peptide on mature dendritic cells antagonizes T helper type 1 polarization.

Dendritic cells (DCs) initiate and regulate immunity against foreign and self antigens. Here we identified more than 200 individual major histocompatibility complex class II-associated peptides on human DCs and found that mature DCs selectively upregulated the self peptide CLIP. CLIP cosegregated together with foreign antigenic peptides in tetraspan microdomains on the surface and localized to DC-T cell synapses. The increased representation of CLIP-major histocompatibility complex class II complexes favored polarization of autologous naive T cells toward the nonpolarized and T helper type 2 (T(H)2) phenotype. There was also a considerably higher T(H)2/T(H)1 ratio in H2-DM-deficient mice, which have a CLIP(hi) phenotype, in contrast to wild-type, CLIP(lo) mice. Thus, the self peptide CLIP on DCs qualifies as an endogenous regulator in priming of T helper cells by antagonizing the polarization toward the T(H)1 phenotype.

Antigen Presentation↗

Quality ratings for frequency-shaped peak-clipped speech: results for listeners with hearing loss.

Peak clipping is a common form of distortion in hearing aids and can reduce the subjective quality of the amplified speech. In a previous study involving listeners with normal hearing (Kates & Kozma-Spytek, 1994), the effect of peak clipping on speech quality ratings was studied using sentence test materials that were filtered using three different frequency response contours and then clipped at four different clipping levels. The present study extends the quality ratings to include those from a group of listeners having moderate to profound hearing impairments. The experimental results indicate that the clipping level, and the interaction of the frequency-response shaping with the clipping level, significantly affects speech quality. It is also shown that the distortion effects on speech quality for the listeners with impaired hearing can be modeled by a distortion index computed from the magnitude-squared coherence of the speech-processing system in response to a shaped-noise input signal. The distortion-index weights derived for the group of listeners with impaired hearing, however, differ substantially from those derived for listeners with normal hearing, and substantial inter-listener variation was also observed.

Audiometry, Speech↗

Discrimination value of the new western prognostic system (CLIP score) for hepatocellular carcinoma in 662 Japanese patients. Cancer of the Liver Italian Program.

To reliably estimate the prognoses of patients with hepatocellular carcinoma (HCC), both liver function and tumor-related factors should be accounted for. However, there are few worldwide staging systems that assess prognostic value in the context of selecting individual patients for randomized stratification in therapeutic and clinical trials. We investigated the value of known prognostic systems and verified the usefulness of the new scoring system proposed by the Cancer of the Liver Italian Program (CLIP), as determined from 662 Japanese patients. A retrospective analysis of the HCC diagnoses at 4 Japanese institutions from 1990 and 1998 was performed. Overall survival was the only end point used in the analysis. Discriminatory ability and predictive power of the CLIP score were compared with those of Okuda stage and AJCC TNM stage. Compared with the Okuda and AJCC staging systems, the CLIP score's enhanced discriminatory capacity, which was tested by the linear trend test and Harrels' c-index, revealed a class of patients with an impressively more favorable prognosis and another class with a relatively shorter life expectancy. Moreover, the likelihood ratio test showed that the CLIP score had additional homogeneity of survival within each score above that of the Okuda stage or the AJCC stage. This was true for 3 subgroups of patients who received surgery, transcatheter arterial chemoembolizations, and percutaneous ethanol injections. Collectively, these findings indicate that the CLIP score has the highest stratification ability with regard to prognosis in patients with HCC. The CLIP score could be used internationally to stratify randomization groups in therapeutic and clinical trials.

Adult↗

Immediate postoperative angiography after aneurysm clipping--implications for quality control and guidance of further management.

BACKGROUND: To determine the impact of postoperative angiography after aneurysm clipping on quality control and further management. METHODS: A recent consecutive series of n = 296 patients (186 females, 110 males, mean age 51 yrs) who underwent 324 craniotomies to clip 384 aneurysms was reviewed. New irregularities on postoperative angiographies were categorized as unrelated (e. g. vasospasm) or related (= vessel occlusion/residuum) to clipping and expected or unexpected by the surgeon. Therapies prompted by these findings as well as subsequent negative sequelae were analyzed. Factors related to negative events were identified by logistic regression (p < 0.05). RESULTS: Twenty-six (8%) unrelated findings prompted medical or intravascular therapy. Of 36 (9.4%) clip-related findings (n = 17 occlusions, n = 19 residua), 14 (3.6%) were unexpected (n = 9 occlusions, n = 5 residua). This was followed by 9 (2.3%, n = 4 occlusions, n = 5 residua) clip readjustments and 6 aggressive medical therapies. Nine patients were scheduled for angiographic follow-up, of which in five performed so far no change of aneurysm remnants was noted. Permanent sequelae from vessel occlusion occurred in 9 cases. Major premature rupture (p < 0.005), giant size/fusiform configuration (p < 0.001), posterior circulation aneurysms (p < 0.05) and ophthalmic segment location (p < 0.008) were significantly related to adverse postoperative findings. The use of microvascular Doppler significantly reduced the rate of unexpected vessel occlusion (3.3 vs. 0.9%). CONCLUSIONS: Apart from the need for quality control in aneurysm clipping--especially with respect to coiling--our results stress the importance of postoperative angiography, because a small, but significant subset of patients will benefit from immediate intervention and/or deserves long-term follow-up.

Angiography↗

The effect of clipping and coiling in acute severe subarachnoid hemorrhage after international subarachnoid aneurysmal trial (ISAT) results.

Cerebral aneurysms are treated by two methods: direct microsurgical clipping and endovascular coiling. Both are selected based on definite guidelines for clinicoradiological criteria as follows: Endovascular therapy comprising of GDC embolization, CSF wash-out with UK or TP A were performed in cases with Hunt and Kosnik grade 4 (GCS 7, 8), and grade 5 (without hydrocephalus or intracranial hemorrhage), age>70 years, subacute stage (4--14 days of vasospasm), basilar aneurysm and peripheral MCA/PCA aneurysms. Microsurgical clipping with a drainage procedure was performed in cases with Hunt and Kosnik grades 0--3, grade 4 (GCS 9--12), age less than 70 years, grade 5 with hydrocephalus or intracerebral hematoma and acute stage (0--3 days after bleed). The patient's outcome was measured using GOS (Glasgow outcome score) at the time of discharge. In our series of severe (poor grade) SAH cases, 120 cases underwent clipping and 59 cases underwent coiling. Although they accounted for 37.8 % and 48 % of total SAH cases, respectively, the outcome was satisfactory. Good recovery and moderate disability, together termed "favorable outcome" was found in 69.16 % of clipping cases and 44.06 % of coiling cases. Clipping had a better outcome than coiling in cases of acute severe SAH in our series. The golden hour resuscitation, pre-hospital care and the adjunctive treatment strategies like hypothermia are discussed. A critical appraisal of the ISAT of microsurgical clipping versus coiling is used for comparison of our results.

Acute Disease↗

An endoscopic aneurysm clip applicator: preliminary development.

Visualization of an aneurysm and its associated vessels is necessary for the proper application of aneurysm clips. Microscopes provide binocular magnification and excellent illumination but often visualization is obscured by overriding vessels and the limitation of the operative approach. If this occurs the aneurysm may be incompletely clipped or small perforators may be included in the clip. In an attempt to improve visualization during aneurysm clipping we have incorporated a small endoscope into the aneurysm clip applicator so that the tips of the clip can be observed at all times. Here we report our initial experimental results with this instrument.

Cadaver↗

Prophylactic clip application does not decrease delayed bleeding after colonoscopic polypectomy.

BACKGROUND: The most common major complication of colonoscopic polypectomy is postpolypectomy hemorrhage. Although several factors have been implicated in the occurrence of hemorrhage, accurate prediction of delayed bleeding remains difficult. This randomized controlled trial evaluated the efficacy of prophylactic clip application for prevention of delayed postpolypectomy bleeding. METHODS: Postpolypectomy ulcers created by colonoscopic removal of polyps (mean size 7.8 [4.0] mm) with the endoscopic mucosal resection technique were randomly assigned to prophylactic clip placement (n = 205) or no clip (n = 208). Baseline characteristics of the patients and polyps excised were comparable between the groups. Delayed bleeding was defined as the postprocedure passage of bloody stool or massive hematochezia. The site of delayed bleeding was identified at emergent colonoscopy. RESULTS: Delayed bleeding was identified from 2 ulcers in each group from 1 to 4 days after resection (mean 2.3 days). Delayed bleeding occurred from 0.98% of ulcers in the clip group and 0.96% in the non-clip group (p > 0.9999). No patient with delayed bleeding required transfusion or surgery. CONCLUSIONS: Prophylactic clip placement did not decrease the occurrence of delayed bleeding after colonoscopic polypectomy.

Adenocarcinoma↗

Comparison of the Ti-knot device and Hem-o-lok clips with other devices commonly used for laparoscopic renal-artery ligation.

BACKGROUND AND PURPOSE: New devices such as the Ti-knot and Hem-o-lok clips have been developed for laparoscopic surgical applications. We compared the effectiveness of Ti-knot TK5 (LSI Solutions), Hem-o-lok MLK clips (Weck Closure), Ligaclip 5-mm titanium clips (Ethicon), and Endopath vascular staples (35 mm long, 12.3 mm wide) (Ethicon). MATERIALS AND METHODS: Renal artery segments from 5 to 6 mm in diameter were harvested from fresh porcine kidneys. One end of the vessel was intubated with a 25-gauge ball-tipped needle and fastened with two silk ties. The other end was occluded with one of the test devices. Saline was infused into each arterial segment at 3 mL/min with the maximum pump pressure at 800 mm Hg. The maximum pressure with leakage was recorded. Each of the five test devices was tested eight times on a rotating basis. Saline infusion was stopped when the maximum pump pressure was reached or when leakage was observed. RESULTS: All Ti-knot devices, Hem-o-lok clips, titanium metal clips, and standard hand ties tolerated pressures >800 mm Hg with no leakage, but 4 of the 8 vascular staple lines (50%) leaked before this maximum pump pressure was reached. For those that leaked, the mean leak pressure was 273 mm Hg (range 237-322 mm Hg). CONCLUSIONS: All devices tested are capable of occluding renal arteries under physiologic conditions. Ti-knot devices and Hem-o-lok clips occluded renal arteries to pressures that exceeded 800 mm Hg. They are equivalent to hand ties under supraphysiologic conditions.

Animals↗

Effect of tragus clips on gastric peristalsis: a pilot study.

In the past 22 years we have used the "hunger point" on the tragus of the ear to induce aversion to cigarette smoking and inhibit appetite for weight reduction with varying degrees of success. This has generally been accomplished by inserting press needles into the tragus of both ears. Because these needles gradually lose effect over a 5- to 7-day period, they have had to be changed every 5 to 7 days. To obviate this need, ear-clips (Aculite; I-Openers, Cranston, RI) were devised to be worn on the tragus. Previous work using press needles on the tragus induced slowing of gastric peristalsis, thought to be mediated by inhibition of a branch of the vagus nerve that innervates the tragus. The present study measured the duration of single gastric peristaltic waves before and after wearing the ear-clips for two cycles. There was a marked prolongation of gastric peristalsis time (GPT) when the ear-clips were applied, a return to baseline times when the clips were off, and a second, but less dramatic prolongation when the clips were on, p = 0.01. We conclude that the ear-clips were effective in delaying gastric peristalsis, and may have value in reducing appetite in association with weight loss programs.

Acupuncture Points↗

Quantitation of force to dislodge endoscopic ligation clips: EndoClip II vs. Ligaclip ERCA.

The mean forces required to dislodge two types of endoscopic ligation clips from both porcine cystic ducts and silicone tubing were quantitated. The two types of endoscopic clips were EndoClip II and Ligaclip ERCA. Following application of the clips, the force required to dislodge the clips in both a perpendicular direction and a longitudinal direction was determined. The mean levels of force required to dislodge the EndoClip II clips in both directions were significantly (p < or = 0.01) greater than those required to dislodge the Ligaclip ERCA clips.

Animals↗

Injuries to Scottish farmers while tagging and clipping cattle: a cross-sectional survey.

BACKGROUND: Anecdotal reports suggested that farmers were sustaining significant injuries while ear tagging newborn calves or clipping cattle prior to slaughter. AIMS: This national survey was designed for determining the incidence and nature of self-reported injuries to farmers that were sustained while tagging calves and clipping cattle. METHODS: A cross-sectional, anonymous, postal questionnaire survey was sent to all members of the National Farmers Union of Scotland with beef or dairy cattle (n = 4495). RESULTS: In total, 2439 (54%) usable questionnaires were received and 1341 injuries were reported by 591 (24%) respondents. Tagging-related injuries were reported by 297 (12%) respondents. The most commonly described injury was bruising, but lacerations (3%) and fractures (3%) also occurred. Fifty-eight (20%) individuals lost time from work, with a median of 3 days [interquartile range (IQR) = 2-7 days]. Four hundred and eighteen (17%) respondents reported clipping-related injuries. The most common injury was bruising, but lacerations (6%) and fractures (7%) also occurred. Ninety-five (23%) individuals lost time from work, with a median of 4 days (IQR = 2-14 days). Tagging injuries more commonly affected lower limbs and the trunk, while clipping injuries affected the upper limbs. Tagging injuries were associated with working alone, in an open field and with a vehicle nearby, while clipping injuries were associated with working alone, with beef cattle and with younger age. Both types of injury were associated with injuries from livestock in other circumstances. CONCLUSIONS: Tagging calves and clipping cattle prior to slaughter are associated with a significant risk of injury, which may be severe, necessitating treatment and time lost from work. Policy makers, safety advisers and the farming community should reconsider whether these procedures are necessary and whether current guidelines should be modified in order to improve safety.

Adult↗

Clinical application of vascular closure staple clips for blood access surgery.

We investigated the usefulness of nonpenetrating titanium vascular closure staple (VCS) clips developed for anastomosis of peripheral blood vessels. VCS clip applier systems (Autosuture; United States Surgical Corporation, Norwalk, CT) were used for 10 patients on hemodialysis who needed peripheral vascular anastomoses for blood access. Two arteriovenous (AV) fistulas, one closure of a fistula with reconstruction of the radial artery, six vascular graft implantations, and one vascular graft closure were performed. Medium clips were used for AV fistulas and large clips for vascular graft implantation. It took 12 min, on average, for vascular access graft anastomoses and 8.5 min, on average, for the AV fistulas. In two patients, bleeding from the anastomosed site occurred after declamping and additional sutures were required; however, neither hematoma nor wound infection occurred at 9 to 12 months after surgery. In one patient, stenosis of the graft-venous junction was found and was successfully treated by percutaneous transluminal angioplasty. The VCS clip applier is easy to manipulate, is as safe as hand-suture methods, and has time saving potential. We conclude that these VCS clips are useful for vascular anastomoses of blood access.

Anastomosis, Surgical↗

Effect of peak clipping on speech recognition threshold.

Speech recognition thresholds (SRTs) were measured for a closed set of spondees that had been processed by peak clipping and compression. Both hearing-impaired and normal-hearing subject groups showed progressively higher SRTs with increasing levels of peak clipping, with significant threshold shifts occurring for clipping levels greater than 18 to 24 dB. Neither subject group showed significantly elevated SRTs for the compression processed stimuli. Magnitude-squared coherence analysis of the speech stimuli revealed high levels of distortion generated by peak clipping and relatively low levels generated by the compression processing. Subsequent analysis suggested that the addition of distortion products and not the alteration of the speech waveform envelope was responsible for the observed threshold shifts, and that coherence analysis may be a valuable tool for predicting the effects of distortion on speech intelligibility. Judgments of sound quality showed that the clipping level where SRTs began to be significantly affected coincided with the clipping level at which the quality of the speech was judged to be unacceptable.

Adult↗

Antihypertensive effect of sialoadenectomy in one-kidney, one clip hypertension in the rat.

We have examined the effect of removal of the submandibular gland on one-kidney, one clip (1K1C) hypertension in the rat. Five weeks after application of a silver clip with a 0.20-mm gap, 15 hypertensive rats were sialoadenectomized. This was followed by a decrease in systolic blood pressure (SBP) within 1 day by 22 +/- 4 mmHg (+/- s.e.m.) and in nine rats pressure stabilized within 1 week at 133 +/- 5 (cf. 166 +/- 2 before sialoadenectomy). In the other six rats the initial hypotensive response was followed by a gradual return to hypertensive levels, reaching 178 +/- 4 mmHg 6 weeks later. Sham-sialoadenectomized rats remained hypertensive throughout. When a 0.15-mm gap clip was used in a similar experiment rats became hypertensive after 2 weeks, and sialoadenectomy lowered SBP to normal in half of them, after which pressure tended to return to hypertensive levels in most. No change in SBP was found in sham-operated hypertensive rats. Sialoadenectomy performed at the time of clipping with a 0.15-mm gap clip and unilateral nephrectomy delayed the development of hypertension. Systolic pressure then fell from 153 +/- 14 at 4 weeks to 105 +/- 8 at 12 weeks after operation in five rats, but continued to increase in eight rats from 148 +/- 10 at 4 weeks to 172 +/- 15 at 12 weeks. These experiments thus demonstrate that the submandibular gland may contribute to the onset and maintenance of one-kidney, one clip hypertension in the rat, particularly in less severe stenosis.

Adrenal Cortex↗