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A new technique for continuous recording of penile rigidity and tumescence has been developed. This methodology has been utilized in initial studies to define erectile function in both normal and impotent males. Accurate recording of tumescence and rigidity have been utilized to document the decline in erectile function associated with organic impotence.
X-ray crystal analysis was performed on block copolyurethanes with peptide links as rigid block extenders. The increase in peptide link length was shown to improve the microphase separation of flexible and rigid segments. The influence of the isocyanate nature on phase separation conditions in the block copolyurethanes studied was established. The correlation between mechanical and temperature characteristics and peculiarities of the microphase structure was found. The latter seems especially important because of the dependence existing between the biodegradation tendency of the polyurethanes and their supermolecular organization.
Twenty-five complications (of which 2 were lethal) occurred in 1332 rigid laryngo-bronchoscopies performed under general anesthesia in the Sophia Children's Hospital during an 8 year period (1982-1990). The nature and circumstances of these complications were studied retrospectively. Important intraoperative complications were hemorrhage and cardiac arrhythmia; postoperative complications were intoxication and respiratory complications. Three risk factors: tetralogy of Fallot, biopsy/drainage, and extraction of an aspirated foreign body appeared to be significantly associated with complications. The results of this study were compared with those reported in studies of rigid and flexible laryngo-bronchoscopies in children.
Artificial implants currently used in orthopaedic surgery and dentistry are anchored to the surrounding bone by rigid mechanical fixation. Long-term studies indicate that the rate of implant failure due to loosening increases steeply after 10 years of function. The loosening is attributed to the micro-movements occurring at the bone implant interface. Non-rigid, self-renewing ligamentous anchorage is nature's solution to the problem of micro-movements. An excellent example of this type of anchorage is the tooth-bone system, where the tooth is anchored to the bone by a fibrous connective tissue. A novel artificial implant, bearing on its surface a unique biological substrate (BS), was designed to induce a ligamentous anchorage of implant to bone. The implant consists of a metallic core to which the BS is bound. The BS is a composite of plastic material and a collagen mesh which is partly incorporated into the plastic material and partly freely extended from its outer surface as artificial Sharpey's fibers. BS fabrication did not affect the capacity of the collagen to withstand non-specific degradation in vitro. Non-weight-bearing implants implanted into the femoral bone of rats induced and maintained a ligament-like tissue up to 4 months. The collagen fibers of the ligament-like tissue were spliced with the artificial BS Sharpey's fibers and were also anchored as Sharpey's fibers into the surrounding bone. Examination of control plastic implants (without the BS) revealed bone formation in close approximation to the implant surface.(ABSTRACT TRUNCATED AT 250 WORDS)
Twenty non-growing subjects underwent sagittal ramus osteotomies and rigid fixation. Cephalograms were analyzed before surgery, immediately after surgery and at least six months following surgery to evaluate skeletal stability. A mean horizontal relapse of 0.42 mm (8%) and a mean vertical increase in lower face height of 0.2 mm were found six months after surgery. Both were statistically insignificant. The mean backward rotation of the mandible of 0.55 degrees found six months after surgery was statistically significant (P less than 0.015), but was considered to be clinically insignificant. The results of this study show that surgical mandibular advancement with rigid fixation is a very reliable and stable procedure.
This study evaluated maximum stimulated molar bite force following advancement of the mandible in 17 adult Macaca mulatta using rigid and nonrigid fixation techniques. Cephalometric analysis was also performed to determine the amount of proximal segment rotation. Analysis of the bite force showed the animals whose mandibles were advanced using rigid fixation to have significantly greater bite force at six weeks postsurgery when compared to those animals who underwent mandibular advancement and six weeks of maxillomandibular fixation. By the ninth postoperative week, there was no longer any significant difference between the two groups, indicating a rapid recovery of muscle function in the animals whose mandibles were immobilized following advancement. Both groups, however, had significant decreases in bite force at 12 weeks postsurgery when compared to preoperative values. Neither group had a significant amount of proximal segment rotation from the surgery.
Twenty subjects receiving Le Fort I downfracture osteotomies stabilized with rigid fixation were studied for relapse. The analysis was based on longitudinal cephalometric radiographs taken within 2 weeks presurgically, 1 week postsurgically, and after a minimum period of 6 months postsurgically. Vertical and sagittal changes in the maxilla were evaluated in reference to the Frankfort horizontal plane. It was found that the mean postsurgical relapse was minimal and not significant. It was smaller than that reported for patients who had received stabilization of the maxilla with intraosseous and maxillomandibular wiring. It was concluded that the rigid fixation technique is dependable and yields stable postsurgical results in the maxilla.
The purpose of this investigation was to determine if the activity of the suprahyoid musculature changes following advancement of the mandible and the use of rigid or nonrigid fixation. Ten monkeys underwent mandibular advancement; six underwent 6 weeks of maxillomandibular fixation (MMF), and four had rigid fixation without MMF. Electromyography (EMG) of the suprahyoid musculature was performed preoperatively, and at 3, 7, and 10 weeks postoperatively. The results of this study fail to demonstrate an increase in suprahyoid EMG activity following mandibular advancement. Furthermore, there were no differences between the groups with different types of fixation.
The postsurgical changes associated with sagittal ramus osteotomy and mandibular setback stabilized with rigid fixation were evaluated. Lateral cephalometric radiographs of 25 individuals (11 males and 14 females) with a mean age of 23.4 years were evaluated presurgery, immediate postsurgery, and after a follow-up period of 7 to 42 months. The mean amount of surgical setback was 5.1 +/- 3.0 mm and the mean amount of postsurgical anterior movement was 0.51 +/- 1.04 mm, representing a 10% relapse of the original surgical correction. The postsurgical relapse of the mandible was not found to be related to the amount of surgical movement. Sixteen of the 18 cases that demonstrated anterior relapse moved forward between 0.5 and 1.5 mm. The amount of relapse was consistent and statistically significant (P less than .05), but small enough that it was not considered to be clinically significant. The findings of this study indicate that mandibular setback with a sagittal ramus osteotomy and its stabilization with rigid fixation appears to be a stable clinical procedure.
This study evaluated the histologic response of the temporomandibular joint (TMJ) following mandibular advancement using rigid and nonrigid fixation in monkeys. Twelve adult female rhesus monkeys underwent sagittal ramus osteotomies with advancement. Six of them were placed into maxillomandibular fixation (MMF); six underwent bicortical bone-screw fixation without MMF. Changes in condylar position were quantified using lateral cephalograms with the aid of bone markers. The animals were killed at 6 weeks and the TMJs were prepared for histologic analysis. Three measures of condylar cartilage thickness were obtained for each animal and were correlated to changes in position of the condyle. Animals who underwent MMF showed a tendency for anterior movement of the condyles; animals who underwent rigid fixation showed a tendency for posterior condylar position. Thicker cartilage layers were found in the MMF animals. Animals who had posterior displacement of the condyles showed evidence of resorption of the posterior surface of the condyle and anterior surface of the postglenoid spine. There was a significant correlation between a change in the horizontal position of the condyle and the thickness of the posterior aspect of the condylar cartilage. The results of this study indicate that alterations in condylar position may induce remodeling changes within the TMJ.
Of 214 patients with mandibular fractures treated following the AO/ASIF principle of rigid fixation, 13 patients (6.1%) developed postoperative infection. The yearly percentage decreased remarkably during the study period. When rigid fixation became a routine method, the infection rate was as low as the corresponding figure for cases treated with nonstable techniques and maxillomandibular fixation (MMF). All but one of the infected fractures were in the angular region of the mandible. Teeth had been extracted from the fracture line in 9 of the 10 dentulous patients. It was concluded that erroneous techniques had been used in almost all infected cases, because compression could not be achieved when there was an irregular fracture line, an atrophic edentulous mandible, or inadequate stability due to removal of a tooth in the line of fracture. In five patients, successful reoperation was performed using a reconstruction plate. Detailed radiologic examination was useful in assessment of infection and in follow-up.
Twenty-three adult female rhesus monkeys underwent advancement of the mandible by the sagittal split ramus osteotomy. Twelve had the proximal and distal segments wired together and underwent 6 weeks of maxillomandibular fixation (MMF). Eleven animals had bicortical bone screws placed between the segments and no postsurgical MMF. The animals were killed at 6 and 12 weeks and the osteotomy sites were prepared for histologic examination. Overall, the results showed that the two groups of animals underwent markedly different patterns of osseous healing. The osteotomy sites in the MMF animals were filled with callus, which then formed bone. In contrast, no callus was found in the majority of the rigid fixation osteotomy sites; direct bony deposition was found instead. The results of this investigation show that, like long bones, the sagittal osteotomy can heal by direct or indirect means depending on the rigidity of the fixation.
The results of using rigid fixation for 75 mandibular fractures in 52 patients and allowing immediate function were retrospectively analyzed. Sixteen percent of fractures developed postoperative infection. All infections were in fractures associated with teeth; none occurred in fractures fixed within 24 hours of injury. Angle and posterior body fractures were most likely to become infected. Fractures with improperly applied rigid fixation also were subject to a high infection rate. It was unusual for infection involving this type of treatment to prolong the course of therapy or affect the final outcome.
OBJECTIVE: To compare two different methods of rigid fixation for any difference in postoperative stability after mandibular advancement. MATERIAL AND METHODS: Thirty-eight patients with Class II malocclusion treated by bilateral sagittal split osteotomy (BSSO) and mandibular advancement were selected for this retrospective study. Group A (n = 16) had noncompressive bicortical screws inserted in the gonial area through a transcutaneous approach and Group B (n = 22) had the bone segments fixed with unicortical screws and miniplates on the lateral surface of the mandibular body. Cephalograms were taken preoperatively, 2 days postoperatively, and 6 months after the operation, and a computer program was used to superimpose the three cephalograms and register the advancement and postoperative instability. RESULTS: There was a minimal difference in advancement of the mandible in the two groups. Statistical analysis showed no significant difference in postsurgical stability. However, positive correlation between the amount of advancement and the amount of postsurgical instability was demonstrated using a linear multiple regression test (P = .0002). CONCLUSION: This study indicates that the two different methods of internal rigid fixation of the segments after surgical advancement of the mandible give equal stability postoperatively and their use is a matter of surgical choice.
PURPOSE: This study compares two types of fixation: intraosseous wires, skeletal suspension wiring, and maxillomandibular fixation (combined wire fixation; CWF) with rigid internal fixation (RIF) in patients who underwent Le Fort I osteotomy to correct maxillary hypoplasia. MATERIALS AND METHODS: All patients were operated on by the same surgeon using a standard technique, which included bone grafting. The 12 patients in group A were treated with CWF for 4 weeks. Group B was made up of 13 patients who had RIF and training elastics for 4 weeks. Cephalometric analysis using a commercial software package was performed on radiographs that were taken immediately preoperatively (T1), 1 day postoperatively (T2), and at least 1 year postoperatively (T4). The position of the maxilla in relation to the cranial base and Frankfort plane at each time interval was compared. RESULTS: Postsurgical horizontal change (maxillary position change from T2 to T4) for both groups was in the posterior direction. In group A, six patients had less than 1 mm change, three had 1 to 2 mm change, and three had > 2 mm change. In group B, 10 patients had less than 1 mm change, three had 1 to 2 mm change and 0 had > 2 mm change. Comparison of mean values of groups A and B suggested improved stability with rigid versus wire fixation in the horizontal plane; however, statistical analysis of adjusted mean values showed no significant difference. Vertical changes in maxillary position were also measured from postoperatively to 1 year (T2 to T4). The vertical changes were minimal in those cases of maxillary advancement where no vertical changes were planned; however, there was a statistically significant (P = .0024) improved stability with RIF versus combined wire fixation cases. Comparison of adjusted means showed double the amount of vertical setting 1 year postoperatively in the CWF group. CONCLUSION: Overall, 22 of 25 patients with horizontal maxillary advancement had excellent stability at 1 year. Observed trends suggest that RIF may have improved stability over CWF.
Two fluorescent derivatives of human fibrinogen have been synthesized, by the covalent bonding of 1-dimethylaminoaphthalene-5-sulphonyl and methylpyrene chromophores, to investigate the internal molecular dynamics of the protein in solution. The stationary fluorescence depolarization of these derivatives under isothermal conditions is described here while in an accompanying paper (part II) a time-resolved study is reported. From the static fluorescence data it is concluded that reorientational processes in the subnanosecond and microsecond time ranges account for all the observed depolarization. The faster motion was assigned to the restricted, localized oscillations of the label while the slow motion was ascribed to the overall rotation of the protein molecule. Consequently, the protein in solution appears considerably rigid in the 10-1000 ns range, in contrast with a previous conception of a flexible fibrinogen based on non-isothermal depolarization experiments. These previous experiments are, in fact, concordant with the rigid fibrinogen proposed here if they are reinterpreted using Weber's early ideas on thermally activated depolarization (G. Weber, J. Biochem. 51 (1952) 145).
1. The effects of a noradrenaline precursor, L-threo-3,4-dihydroxyphenylserine (L-DOPS), on spinal mono-(MSR) and polysynaptic reflexes (PSR) and decerebrate rigidity, were studied. 2. Although a low dose of L-DOPS (10 mg/kg, i.v.) did not affect MSR or PSR in C1 spinal rats, high doses of L-DOPS (50 and 100 mg/kg, i.v.) moderately enhanced the amplitudes of both MSR and PSR. 3. Clorgyline-HCl (1 mg/kg, i.v.), an MAO inhibitor, enhanced the excitatory effects of low-dose L-DOPS (10 mg/kg, i.v.) on both reflexes. 4. Benserazide-HCl (1 mg/kg, i.v.), an L-aromatic amino acid decarboxylase inhibitor, decreased the pressor effect, but not the stimulatory effects, of L-DOPS (100 mg/kg, i.v.) on MSR and PSR. 5. L-DOPS (300 mg/kg, i.p. or i.d.) did not affect the muscle tone of rigid hindlimbs caused by radio frequency lesioning of the midbrain. 6. These results suggest that the moderate enhancing effects of L-DOPS on MSR and PSR are due to conversion of L-DOPS to noradrenaline in the spinal cord.
1. The possible role of conformational requirements which fenfluramine and norfenfluramine must satisfy to elicit its observed pharmacological activities was investigated in mice with the use of four conformationally-rigid norfenfluramine analogues. 2. In this study, both the syn-9-amino and endo-2-amino isomers, which structurally resemble the gauche conformation of norfenfluramine, were found to have little or no effect on spontaneous locomotor activity. 3. On the other hand, the isomers (i.e. the anti-9-amino and exo-2-amino isomers) that mimic the anti conformation of norfenfluramine were capable of causing a decrease in spontaneous motor activity similar to that of norfenfluramine. 4. The analgesic activities of these rigid analogues were also assessed and all of the isomers were found to be weakly analgesic. 5. Only the exo-2-amino isomer exhibited analgesic potency similar to that of fenfluramine. Furthermore all of these compounds were capable of enhancing the analgesic activity of morphine.