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PubMed2001

Rigid multilamellar bilayer cooperativity is modified by non covalently linked neuraminic-5-acid: a spectrophotometric determination.

By means of recording a simple serie of merocyanine 540 spectra, we present a method to calculate the value proportional to co-operative unit size of membranes (n). Our calculations, applied to different liposomal samples processed in the presence or absence of sugars, in high or low ionic strength showed two main results. First, that any temperature cycling in high ionic strength of rigid DPPC bilayers will modify the membrane cooperativity. Second, the presence of polysaccharide Neu-5-ac in solution will always produce a strong drop in co-operativity of a rigid membrane of DPPC, whenever the negative charge is fully exposed. This last result indicates a differential ability of charged Neu-5-ac to disrupt a rigid membrane structure, even in the absence of a covalent linkage and--remarkably-in fully hydrated media.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

[Arterial rigidity and cardiovascular vagosympathetic activity in normotensive and hypertensive obese patients and type 2 diabetics].

An increase in arterial rigidity is associated with a poor cardiovascular prognosis. Several studies have suggested that an increase in sympathetic activity may be involved in essential hypertension. We have recently shown that vagal control of heart rate (HR) variations during standardised tests is altered in normotensive obese and diabetic patients. The aim of the present study was to compare cardiovascular vagosympathetic activity in obese and type 2 diabetic patients, either normotensive or hypertensive, and to investigate the relationship between pulse pressure (an index of arterial rigidity) and sympathetic activity in this population. Seventy normotensive obese and 32 mildly hypertensive obese patients, 18 normotensive type 2 diabetic patients and 14 mildly hypertensive type 2 diabetic patients were compared with 21 control subjects. Finapres studied HR and blood pressure variations. In the four groups, during a 6-min period at a controlled breathing rate, the high frequency peak of HR variations was significantly reduced (p < 0.001). The mid-frequency peak of systolic BP variations in the standing position, which depends on sympathetic activity, did not differ significantly between the four groups and control subjects. In obese and diabetic hypertensive patients, this peak correlated significantly with pulse pressure measured in the lying position (r = 0.379; p = 0.043 and r = 0.81; p < 0.0001, respectively). This study 1, confirms that vagal control of HR variations is reduced to a similar extent in obese and diabetic patients; and 2, suggests that cardiovascular sympathetic activity is relatively increased in these patients without significant difference between normotensive and hypertensive patients, but interestingly that the increase in arterial rigidity is associated with a higher sympathetic activity.

Adult↗
PubMed2001

Rigid bronchoscopy: the value of a venerable procedure.

The rigid bronchoscope is a unique and invaluable instrument that allows evaluation, control, and therapeutic manipulation of the proximal tracheobronchial tree. Massive hemoptysis, foreign body removal, airway stenosis, laser resection, and pediatric bronchoscopy are the most common indications for the rigid bronchoscope. Improved anesthetic agents have improved the safety and comfort of the procedure for patients having either diagnostic or therapeutic procedures. The ability to use the rigid bronchoscope in therapeutic situations depends, however, on a level of skill and experience with the instrument that can be obtained only by its frequent use for diagnostic indications in the proximal airway.

Anesthesia↗
PubMed2002

Nitric oxide levels in tears of patients with mild forms of papillary conjunctivitis induced by rigid gas-permeable contact lenses.

PURPOSE: To determine whether nitric oxide (NO) is detectable in the tear fluid of patients with mild forms of papillary conjunctivitis who wear rigid gas-permeable contact lenses. METHODS: Tear samples were taken from 12 users of rigid gas-permeable contact lenses and 12 healthy controls. Samples were analyzed, and the levels of NO were determined. RESULTS: The mean level of NO in those who wore contact lenses was 118.98 micromol/L (95% CI: 91.85-146.10 micromol/L); whereas the level of NO found in the control subjects was 114.84 micromol/L (95% CI: 102.54-127.14 micromol/L). The difference was statistically insignificant (P>0.05). CONCLUSION: Nitric oxide levels in the tear fluid of rigid gas-permeable contact lens users did not correlate with the presence of mild symptoms of papillary conjunctivitis.

Adolescent↗
PubMed1999

The relationship between porosity, collagen fiber orientation and strength of plated bone after rigid plate fixation and removal.

OBJECTIVE: To understand the relationship between porosity, collagen fiber orientation and strength of the plated bone after rigid plate fixation and removal. METHODS: Seventy-two New Zealand white rabbits were used in this experiment. Eight animals served as control and the other sixty-four were plated on their intact left tibiae with stainless steel (316L) 4-hole plates to induce early osteoporosis. The plates were removed 2 months after internal fixation in 40 plated animals, 8 of which were sacrificed immediately following plate removal and the other 32 were killed in successive groups with 8 in each group 1, 2, 3 and 4 months after plate removal. The remaining 24 plated animals were killed at 3, 4 and 6 months after plate fixation. After sacrifice, the samples of plated bone were prepared for light microscope, quantitative histological analysis, polarized light microscope and biomechanical test. RESULTS: The internal fixation with a rigid plate could induce the regional osteoporosis which manifested both bone loss and disorganized bone structure (loss of the orientation of the collagen fibers) leading to decreased strength of the plated bone. Although the regional osteoporosis could recover gradually after plate removal, the bone structure remained disorderly even when the bone mass returned to normal. Delayed restoration of bone structure was related to delayed restoration of bone strength. CONCLUSIONS: Besides the bone loss, the disorganized bone structure is the main cause of decrease of bone strength after rigid plate fixation and removal.

Journal Article↗
PubMed2002

Impact of rigid gas-permeable contact lens extended wear on corneal epithelial barrier function.

PURPOSE: To measure the effect of hypoxia and eye closure on epithelial permeability to fluorescein (P(dc)) during rigid lens extended wear (EW). METHODS: Central corneal thickness (CT) and P(dc) were measured in 42 subjects with an optical pachometer and automated scanning fluorophotometer, respectively. All subjects had been successfully wearing rigid gas-permeable (RGP) lenses on a 6-night EW regimen, and each individual was randomized to wear either medium- or high-oxygen-permeable (Dk) RGP lenses (two types of siloxane-fluorocarbon polymer lenses with Dk of 49 and 92). CT and P(dc) measurements were performed at an afternoon visit (baseline) and were repeated in the morning after 8 hours of overnight wear. Subjects slept with a patch over the right eye. The patch was not removed until immediately before the morning measurement. RESULTS: The mean overnight swelling response for subjects in the medium-Dk group was greater than that in the high-Dk group. Results of a paired t-test indicate that the eye wearing the medium-Dk lens with a patch overnight had a significant increase in epithelial permeability. Results of mixed-effect models suggest that eye closure and lens-induced hypoxia are significant factors in altering P(dc). CONCLUSIONS: The results indicate that corneal epithelial permeability increases with hypoxic dose and that epithelial barrier function is impaired by overnight rigid lens wear.

Adult↗
PubMed1996

Complications of rigid internal fixation for mandibular fractures.

The application of rigid internal fixation to maxillofacial trauma is among the truly great advances that have been made in the field. The use of rigid internal fixation techniques has resulted in many advantages for the patient. Unfortunately, complications have occurred with this technology that are often devastating in their consequences for treatment outcomes. This article addresses some of the problems that stem from the use/misuse of rigid fixation devices in the treatment of mandibular fractures. It presents the most common complications and their management, including malunion, fibrous union, infection/osteitis, and impalement of the tooth roots and/or inferior alveolar canal.

Alveolar Process↗
PubMed2003

Is same-day discharge suitable following rigid esophagoscopy? Findings in a series of 655 cases.

It has been suggested that more otolaryngologic procedures should be performed on an outpatient basis, and that rigid upper aerodigestive tract endoscopy might be a particularly suitable procedure in this regard. To determine if this is indeed the case, we retrospectively reviewed the records of 563 patients who had undergone 655 rigid esophagoscopies in our unit between Jan 1, 1991, and July 31, 1998. We ascertained the rate of complications (primarily esophageal perforation) following such procedures and, when they did occur, we determined the length of time between surgery and the onset of the complications' signs and symptoms. Our aims were to establish the minimum duration of postoperative observation that is required following esophagoscopy and to propose criteria for safe same-day discharge. We found that perforation rates were 4.5% following therapeutic procedures (dilation, biopsy, and foreign-body removal) and 1.2% following diagnostic procedures. In 40% of the patients who experienced perforations, no such signs or symptoms were noted within the first 8 hours following surgery. This finding has important implications for surgeons who wish to perform rigid esophagoscopy on an outpatient basis.

Adolescent↗
PubMed2003

[Non-osteogenic malocclusion after anatomic reduction and miniplate rigid fixation in condylar neck and subcondylar fractures].

OBJECTIVE: To analysis the cause of malocclusion that was found in patients suffering from condylar neck and subcondylar fractures after perfectly anatomic reduction and rigid fixation. METHODS: There were 23 cases of malocclusion in the patients of condylar neck and subcondylar fractures after anatomic reduction and rigid fixation during 1994 to 2001. The possible reasons were studied, and the treatment methods were proposed. RESULTS: Both distortion and(or) fracture of miniplates and displacement anain of the condylar process after operation were not found in all 23 cases. There were 6 cases of open bite at the molar teeth of the fractured side, while the normal occlusions were showed in the nonfractured side. 11 cases showed that the whole mandibles were moved slightly to the nonfractured side. 4 cases showed that the mandible of fractured side moved slightly to the nonfractured side and the occlusion of nonfractured side were normal. 2 cases showed premature contact at the fractured molar teeth and the anterior teeth showed open bite. There were 5 cases of facial nerve damages, 2 cases wound infection, 2 cases TMJ chronic pain and 1 cases TMJ click and(or) murmur. CONCLUSIONS: Although the anatomical reduction and miniplate rigid fixation were operated on the condylar neck and subcondylar fractures, there were probably having the chance of showing malocclusion. The malocclusion was not caused by the fracture itself, but in the TMJ and/or muscular injury. Therefore, the malocclusion can be cured with intermaxillary elastic traction and functional exercise. Sometimes, the occlusal adjustment may be performed to resume the normal occlusion. In any case, operation is not needed.

Adult↗
PubMed2004

[Retromandibular incision and miniplate rigid fixation for condylar and subcondylar fractures].

PURPOSE: To report the method and effects of anatomical reduction by retro-mandibular incision and miniplate rigid fixation for condylar and subcondylar fractures. METHODS: Twenty-four condylar neck and subcondylar fractures including 18 unilateral and 6 bilateral in 24 consecutive patients were studied. The fractures were approached by retromandibular incision and miniplate rigid fixation. Postoperative follow up was 3 to 6 months. The treatment results were evaluated including occlusion,joint functions as well as radiographic assessment of condylar changes. RESULTS: The average mouth opening deviation was 6.2mm before operation, which reduced to 1.4mm 3 months after surgical treatment,3 patients had malocclusion,2 had facial nerve damages. CONCLUSION: Miniplate rigid fixation by retromandibular incision based on anatomical reduction is an effective procedure in treating severely displaced and dislocated neck of condyle and subcondylar fractures.

Adult↗
PubMed2004

Subciliary incision and lateral cantholysis in rigid internal fixation of zygomatic complex fractures.

OBJECTIVE: To introduce the technique of subciliary incision and lateral cantholysis with tri-dimension reduction and rigid internal fixation to treat zygomatic complex fractures. METHODS: The subciliary incision and lateral cantholysis combined with tri-dimension reduction and rigid internal fixation of zygomatic complex fractures with titanium microplates were applied in 56 patients with zygomatic complex fractures. Another lateral eyebrow incision or sublabial incision was used to simplify the operation. RESULTS: The postoperative follow-up period ranged from 6 months to 5 years. During the follow-up period, all the patients had satisfying postoperative results. All clinical symptoms disappeared except the numbness in the infraorbital region in 2 patients. In 94.6% patients no complications such as obvious scar, ectropion, entropion or blepharoedema were found, only 5.4% of the patients had slight ectropion 6 months after operation. CONCLUSIONS: The subciliary incision and lateral cantholysis have many advantages such as invisible scar, sufficient exposure, minimal injury, and few complications and combined with rigid internal fixation with titanium microplates this technique could be used as one of the routine operation methods to treat zygomatic complex fractures.

Adolescent↗
PubMed2002

Short-term rigid and flaccid paralyses diminish growth of embryonic chick limbs and abrogate joint cavity formation but differentially preserve pre-cavitated joints.

The influence of movement on joint space formation during limb development has been the subject of much interest. Our aim was to investigate the short-term influence of movement upon cavitation by immobilizing chick embryos in ovo, both in a rigid manner where dynamic stimulation is removed, and a flaccid manner where both dynamic and static stimulation are absent. Induction of rigid immobilization with decamethonium bromide (DMB) or the novel induction of flaccid immobilization with pancuronium bromide (PB) for 3 days, during the normal cavitation of joints resulted in the loss of cavity formation. Immobilization after the formation of an overt cavity demonstrated that static stimulation (during rigid paralysis) was able to maintain joint cavities and preserve some of the hyaluronan (HA) content of articular surfaces, whereas flaccid paralysis resulted in the loss of cavities and a marked depletion of HA content. Assessments of the growth and deposition of cartilage and bone in the limbs of embryos immobilised during cavitation showed that the length of limb elements was greatly reduced and that decreases in epiphyseal widths were most marked and more pronounced distally. The volume of bone in these elements remained unchanged whereas the cartilage volume decreased significantly, suggesting that chondrogenic but not osteogenic events in the embryo are particularly sensitive to mechanical stimulation. In addition to describing a novel method of inducing flaccid immobility in ovo, these data point towards the important role of both static and dynamic stimuli in the growth of embryonic limbs and the development of a functional joint space.

Journal Article↗
PubMed1992

Cleaning and storage of rigid contact lenses prior to dispensing.

Most care regimens used with rigid contact lenses are composed of three solutions: 1) a "cleaning" solution; 2) a "combination" solution intended for storage, disinfection, and wetting prior to placement of rigid lenses on the eye; and 3) an in-eye "rewetting" or "lubricating" solution. While solutions (1) and (3) have only single functions, solution (2) must fulfill three fairly disparate functions. A "2-solution" care regimen is offered by Sherman Pharmaceuticals and consists of (a) a solution for cleaning, storage, and disinfection; and (b) a "wetting" solution that doubles as an in-eye lubricant. Through a more compatible and efficient matching of multiple functions within solutions, Sherman Pharmaceuticals claims to more adequately clean and prepare rigid gas-permeable (RGP) lens surfaces for wear. We investigated this strategy in terms of in-eye wettability of initially "ill-prepared" RGP lens surfaces, as measured with the in vivo contact angle technique. For this study, lenses were intentionally not cleaned of residues or solvents by the manufacturer at the end of production so as to create the well-known "first-day non-wetting syndrome." The ability of the 2-solution care regimen to even then provide wettable surfaces was compared to that of a saline control "regimen" and the most popular competing "3-solution" care system. We concluded that use of both care regimens dramatically enhanced in-eye wettability and, therefore, reduced the incidence of the "first-day non-wetting syndrome". However, the 2-solution care regimen provided significantly better wettability overall, lower incidence of functionally non-wetting surfaces, and more consistently wettable RGP lenses.

Contact Lenses↗
PubMed2005

[The operation treatment for severe and rigid idiopathic scoliosis].

OBJECTIVE: To discuss the operation treatment for the severe and rigid idiopathic scoliosis. METHODS: The clinical data of 24 patients with severe and rigid idiopathic scoliosis, 15 females and 9 males, with an average age of 17 (12 approximately 20) who had undergone operations from June 1999 to June 2003 were analyzed retrospectively. The patients were classified according to PUMC operative classification systerm, including 16 cases of type Ia, 2 cases of type Ib, 3 cases of type IIb2, and 1 case of types IIb1, IIc2, and IIc3 each. The average standing coronal Cobb angle was 98 degrees (80 degrees to 117 degrees ) and the average flexibility rate of the major curves was 20.8% (5% to 29.5%) before operation. Fifteen cases had sagittal deformities. Bone fusion was performed on all the cases according to the PUMC classification principles. 17 cases received anterior spinal release with posterior correction by two stages, and 2 cases by one stage. 5 cases received one-stage posterior correction. All the patients were followed up for 12 approximately 30 months (18 months on average). RESULTS: The mean standing coronal Cobb angle of the major curves was reduced to 58 degrees (32 degrees to 100 degrees ) after operation with a correction rate of 41.0% (10.9% to 61.0%). The results of sagittal plane correction were satisfying. The mean Cobb angle of the major curves at the final follow up was 63 degrees (31 degrees to 104 degrees ), and the mean lost was 5 degrees (0 degrees to 10 degrees ). One case had to undergo revision surgery because of hook displacement. One case had steel wire broken but without neurological symptoms and only needed observation. No pseudoarthrosis and decompensation occurred. CONCLUSION: Compared with vertebral osteotomy for the correction of scoliosis, the anterior spinal release combined with posterior correction and simple posterior correction have the advantages of low risk, less blood loss, and low infection rate. They can be used effectively and safely for the correction of idiopathic severe and rigid idiopathic scoliosis. The key points for the surgical procedures are appropriate correction and recovery of the balances of the coronal and sagittal planes.

Adolescent↗
PubMed2005

[Arterial rigidity of patients operated successfully for coarctation of the aorta without residual hypertension].

In patients successfully operated for coarctation of the aorta, the prevalence of hypertension is higher than that observed in the general population although the exact mechanism is not known. The hypothesis of increased arterial rigidity despite satisfactory correction of the coarctation has been proposed. The authors undertook 24 hour ambulatory blood pressure monitoring coupled with measurement of the QKD interval (pulse wave velocity) in order to evaluate the rigidity of the large arteries. These results were compared with those obtained in control patients paired with respect to gender, age, height and weight. Twenty-six patients with an average age of 14.5 +/- 2.9 years were included (age at time of surgery 6.3 +/- 3.7 years). The statistical data confirmed a higher systolic blood pressure (p<0.05) in the operated patients compared with controls. The results confirm the hypothesis of increased residual arterial rigidity in children operated for coarctation of the aorta which could predispose to secondary hypertension, especially on effort. In the long term, this could be an unquestionable cardiovascular risk factor explaining the increased cardiovascular morbid-mortality compared with the general population.

Adolescent↗
PubMed2005

[Treatment of condylar fracture by external pterygoid muscle-condyle anatomical reduction and internal rigid fixation with mini titanium plates].

PURPOSE: To investigate the surgical indications, procedures and treatment outcomes of condylar fracture by external pterygoid muscle-condyle anatomical reduction and internal rigid fixation with mini titanium plates. METHODS: Patients with dislocation of the condylar head, fracture of the condylar neck and subcondylar neck (the degree of displacement greater than 30 to 45) and decreased vertical height of the ramus (greater than 4 to 5mm) were included in the study. Modified aural-temporal stick-shaped incision or retromandibular approach was adopted in 23 cases with 28 condylar fractures. The fractures were treated by external pterygoid muscle-condyle anatomical reduction and internal rigid fixation with mini tension band titanium plates. All the patients were re-examined and evaluated 3 to 6 months after surgery in respects of facial symmetry, mouth opening, types of mouth opening, occlusion and mastication. RESULTS: All the patients had symmetrical face, mouth opening increased from 26.7+/-7.2 (before surgery) to 38.4+/-5.6 (3 months after surgery) and 37.2+/-4.5 mm(6 months after surgery). 2 patients with postoperative malocclusion had intermaxillary distraction for 1 week and their occlusion returned to normal. Radiographic check-up showed the condyle and titanium plates without displacement. No absorption was noted on the condylar surface. The patients had normal mastication. 2 patients with temporal facial paralysis recovered 3 months after conservative therapy. CONCLUSION: Treatment of condylar fracture by external pterygoid muscle-condyle anatomical reduction and internal rigid fixation with mini titanium plates in selected patients is an effective procedure for recovery of anatomical positions and masticatory function. Supported by Research Fund from Science and Technology Bureau of Jining city.

Bone Plates↗
PubMed2005

Apical rigidity of an epithelial cell monolayer evaluated by magnetic twisting cytometry: ICAM-1 versus integrin linkages to F-actin structure.

Using Magnetic Twisting Cytometry (MTC) technique, we attempted to characterize in vitro the rigidity of the lining tissue covering the lung alveolar wall from its apical face. We purposely used a cellular model constituted by a monolayer of human alveolar epithelial cell (A549) over which microbeads, fixed to InterCellular Adhesion Molecule (ICAM-1), exert a controlled mechanical stress. ICAM-1 expression was induced by Tumor Necrosis Factor-alpha (TNF-alpha). Rigidity measurements, performed in the course of cytochalasin D depolymerization, reveal the force transmitter role of the transmembrane receptor ICAM-1 and demonstrate that ICAM-1 and F-actin linkages confers mechanical rigidity to the apical face of the epithelial cell monolayer resembling that provided by integrins. These results confirm the ability of MTC in identifying transmembrane mechanoreceptors in relation with F-actin. Molecular linkages between ICAM-1 and F-actin were observed by spatial visualisations of the structure after double staining of F-actin and anti ICAM-1 antibody through confocal microscopy.

Actins↗
PubMed2006

MR findings of decerebrate rigidity with preservation of consciousness.

We describe a case of decerebrate rigidity, with preservation of consciousness, caused by a discrete pontine tegmentum lesion identified on MR imaging. Lesions within a certain brain stem region are responsible for decerebrate rigidity in animal studies, but there has been a lack of MR imaging evidence in humans. This report also implies that a discrete lesion was responsible for the decerebrate rigidity, while consciousness was preserved.

Consciousness↗