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Results for “COLLAPSE”

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At least 19 recordsLinked to original sources

PubMed1983

Computed tomography of lobar collapse: 2. Collapse in the absence of endobronchial obstruction.

The computed tomographic appearance of collapse without endobronchial obstruction is reviewed. These 57 cases were classified by the etiology of collapse. The largest group consisted of 29 patients with passive atelectasis, i.e., collapse secondary to fluid, air, or both in the pleural space. Twenty-three of 29 proved secondary to malignant pleural disease. Computed tomography accurately predicted a malignant etiology in 22 of 23 cases. The second largest group of patients had lobar collapse secondary to cicatrization from chronic inflammation. In all cases the underlying etiology was tuberculosis. Radiation caused adhesive atelectasis in six patients secondary to a lack of production of surfactant. In each case a sharp line of demarcation could be defined between normal and abnormal collapsed pulmonary parenchyma. Three cases of unchecked tumor growth caused a peripheral form of collapse (replacement atelectasis). This form of collapse was characterized by an absence of endobronchial obstruction and extensive tumor not delineated by the normal boundaries of the pulmonary lobes.

Cicatrix↗

PubMed1995

Localized collapsing cues can steer growth cones without inducing their full collapse.

Collapsing factors are proteins that induce growth cone collapse and paralysis when added in a soluble form to cultured embryonic neurons. Here we examine the responses of growth cones to localized collapsing signals. Temporal retinal ganglion cell growth cones exposed to a localized collapsing stimulus from nasal retinal ganglion cell axons frequently turn smoothly away from the axons without collapsing. Turning is rare on contact with retinal axons that are unable to induce collapse. In a separate series of experiments, dorsal root ganglion growth cones tend to turn away from beads coated with a brain extract enriched for the motility-inhibiting protein collapsin. Many turns are accomplished with filopodial contact alone. Growth cones do not turn away from control beads coated with heat-inactivated collapsin. These results suggest that inhibitory guidance cues can steer growth cones through a localized inhibition of lamellipodial protrusion.

Animals↗

PubMed1999

Myelin and collapsin-1 induce motor neuron growth cone collapse through different pathways: inhibition of collapse by opposing mutants of rac1.

Precise growth cone guidance is the consequence of a continuous reorganization of actin filament structures within filopodia and lamellipodia in response to inhibitory and promoting cues. The small GTPases rac1, cdc42, and rhoA are critical for regulating distinct actin structures in non-neuronal cells and presumably in growth cones. Collapse, a retraction of filopodia and lamellipodia, is a typical growth cone behavior on contact with inhibitory cues and is associated with depolymerization and redistribution of actin filaments. We examined whether small GTPases mediate the inhibitory properties of CNS myelin or collapsin-1, a soluble semaphorin, in chick embryonic motor neuron cultures. As demonstrated for collapsin-1, CNS myelin-evoked growth cone collapse was accompanied by a reduction of rhodamine-phalloidin staining most prominent in the growth cone periphery, suggesting actin filament disassembly. Specific mutants of small GTPases were capable of desensitizing growth cones to CNS myelin or collapsin-1. Adenoviral-mediated expression of constitutively active rac1 or rhoA abolished CNS myelin-induced collapse and allowed remarkable neurite extension on a CNS myelin substrate. In contrast, expression of dominant negative rac1 or cdc42 negated collapsin-1-induced growth cone collapse and promoted neurite outgrowth on a collapsin-1 substrate. These findings suggest that small GTPases can modulate the signaling pathways of inhibitory stimuli and, consequently, allow the manipulation of growth cone behavior. However, the fact that opposite mutants of rac1 were effective against different inhibitory stimuli speaks against a universal signaling pathway underlying growth cone collapse.

Actins↗

PubMed1993

Emergency vehicle intervals versus collapse-to-CPR and collapse-to-defibrillation intervals: monitoring emergency medical services system performance in sudden cardiac arrest.

STUDY OBJECTIVE: To compare emergency vehicle response intervals with collapse-to-intervention intervals to determine which of these system data better correlated with survival after prehospital sudden cardiac arrest. STUDY DESIGN: A 22-month case series, collected prospectively, of out-of-hospital cardiac arrests. Times of collapse, dispatch, scene arrival, CPR, and initial defibrillation were determined from dispatch records, recordings of arrest events, interviews with bystanders, and hospital records. SETTING: Southwestern city (population, 400,000; area, 390 km2) with a two-tiered basic life support-advanced life support emergency medical services system. Emergency medical technician-firefighters without electrical defibrillation capability comprised the first response tier; firefighter-paramedics were the second tier. PATIENTS: One hundred eighteen cases of witnessed, out-of-hospital cardiac arrest in adults with initial ventricular fibrillation. MAIN OUTCOME MEASURES: Survival was defined as a patient who was discharged alive from the hospital. RESULTS: Eighteen of 118 patients (15%) survived. Survivors did not differ significantly from nonsurvivors in age, sex, or basic life support or advanced life support response intervals. Survivors had significantly (P < .05) shorter intervals from collapse to CPR (1.7 versus 5.2 minutes) and to defibrillation (7.4 versus 9.5 minutes). CONCLUSION: Collapse-to-intervention intervals, not emergency vehicle response intervals, should be used to characterize emergency medical services system performance in the treatment of sudden cardiac death.

Aged↗

PubMed2000

Longer time kinetics of collapse transition of polymer-surfactant complexes at interfaces near to collapse temperatures.

The later stages of the collapse transition kinetics of fractionated poly(N-isopropylacrylamide) (PNIPAM) chains at interfaces in the presence of the surfactant sodium dodecyl sulfate (SDS) were studied for molecular weights ranging from 4.5x10(5) to 1.6x10(6). The interfacial PNIPAM-SDS complexes were quickly heated to the temperatures that were near to the collapse transition temperatures. The longer time collapse of the PNIPAM-SDS complexes at interfaces was found to proceed through two stages. The collapse kinetics at the later stages was interpreted in terms of a "globule growth" model. It was found that under the experimental conditions, the fast relaxation time was independent of the molecular weight, whereas the slow relaxation time was weakly dependent on the molecular weight.

Journal Article↗

PubMed2001

Structural Analysis of Collapsed, and Twisted and Collapsed, Multiwalled Carbon Nanotubes by Atomic Force Microscopy.

A fully collapsed multiwalled carbon nanotube (MWCNT1) section and a different twisted and fully collapsed MWCNT were observed with tapping-mode atomic force microscopy. The collapsed section of MWCNT1 was significantly more flexible than the uncollapsed sections, and advanced 120 nm within 1 month. The collapse of MWCNT1 was most likely initiated by its interaction with the surface, and possibly a water meniscus. The ability of carbon nanotubes to radially deform under the influence of surface interactions is in striking contrast with their extremely high axial rigidity.

Journal Article↗

PubMed2006

Collapsing and non-collapsing focal segmental glomerulosclerosis in kidney transplants.

BACKGROUND: The aetiological and clinical associations of collapsing focal segmental glomerulosclerosis (cFSGS) following kidney transplantation (KTx) are poorly described. In this study, post-transplant cFSGS and non-collapsing FSGS (ncFSGS) were compared in recent KTx recipients. Evidence for intragraft viral infection was sought. METHODS: Twenty-nine cases of post-KTx FSGS were identified and classified as cFSGS (n = 10) or ncFSGS (n = 19). Biopsies were scored using Banff '97 criteria and subjected to in situ hybridization (ISH) for parvovirus B19 (pvB19), simian virus 40 (SV40) and BK virus (BKV). RESULTS: cFSGS and ncFSGS patients were comparable for age, gender, weight, delayed function, human leucocyte antigen (HLA) matching, acute rejection and median time to diagnosis. Deceased donor source was more common among cFSGS cases (70 vs 32%, P = 0.05). FSGS was recurrent in 2/10 cFSGS cases compared with 8/19 ncFSGS (P = NS). cFSGS was associated with more proteinuria (11.9 vs 7.2 g/day, P = 0.05) and higher serum creatinine (4.2 vs 1.9 mg/dl, P = 0.0001) at diagnosis. Plasmapheresis was used in two out of 10 cFSGS and seven out of 19 ncFSGS cases with treatment response in 0 of two and three of seven, respectively. Graft loss was more rapid with cFSGS compared with ncFSGS (P = 0.02). Histologically, cFSGS was associated with more severe chronic vascular abnormalities. All biopsies were negative for pvB19, SV40 and BKV by ISH. CONCLUSIONS: cFSGS following KTx presents with higher proteinuria, diminished renal function, more severe vascular disease and higher rate of graft loss compared with the non-collapsing form. There was no evidence for infection by pvB19 or polyomaviruses.

Adult↗

PubMed2006

Long-term results of midcarpal arthrodesis in the treatment of scaphoid nonunion advanced collapse (SNAC-Wrist) and scapholunate advanced collapse (SLAC-Wrist).

UNLABELLED: Outcome evaluation of midcarpal arthrodesis in the treatment of scaphoid nonunion advanced collapse (SNAC-wrist) and scapholunate advanced collapse (SLAC-wrist). PURPOSE: Scaphoid nonunion or scapholunate ligament instability results in carpal collapse and subsequent arthrosis. These conditions, termed SLAC-wrist and SNAC-wrist, are the most common patterns of arthrosis in the wrist. The purpose of this retrospective study was the evaluation of functional outcomes following midcarpal arthrodesis and of patients' satisfaction with these outcomes. METHODS: Forty-nine patients were reexamined at a mean follow-up time of 47 months. Active range of motion (AROM) was verified with a goniometer; grip strength was measured with a JAMAR-Dynamometer II. Pain was evaluated by a visual analogue scale from zero to 100 (VAS 0-100) for stress and under resting conditions. Patients' upper-extremity functioning was captured with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Radiographic evaluation of bony consolidation was verified by conventional x-ray. RESULTS: Postoperative AROM was 56% and grip strength was 76% compared with the contralateral side. The DASH score was 29 points. Pain relief was 34% at rest and 31% after stress. Forty-five patients demonstrated bony consolidation in x-ray control. Six patients (12%) further required a total arthrodesis of the wrist because of pain or absence of bony consolidation. CONCLUSION: Our data demonstrate that midcarpal arthrodesis is a reliable procedure for treating SLAC- and SNAC-wrists in stages II and III and, furthermore, one which preserves some range of motion. Total wrist fusion should only be used in exceptional circumstances.

Adult↗

PubMed1990

Atypical collapse of the upper lobe of the right lung simulating combined right upper and middle lobe collapse: report of two cases.

The authors describe two cases of collapse of the upper lobe of the right lung simulating the appearance on plain chest radiographs of collapse of the right upper and middle lobes combined. Computed tomography and bronchoscopy in both cases and surgery in one case showed that the middle lobe was normal. Possible mechanisms for this appearance on plain chest radiographs include the presence of adhesions between the obstructed upper lobe and pleura and the presence of obstructive pneumonia in the upper lobe, preventing typical collapse.

Aged↗

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