A Microsphere Immunoassay for the Quantitative Detection of Antigens in Cell Culture Supernatant.

Quantitative immunoassays, such as the traditional enzyme-linked immunosorbent assay (ELISA), are used to determine concentrations of an antigen in a matrix of unknown antigen concentration. Magnetic immunoassays, such as the Luminex xMAP technology, allow for the simultaneous detection of multiple analytes and offer heightened sensitivity, specificity, low sample volume requirements, and high-throughput capabilities. Here, we describe a quantitative immunoassay using the Luminex MAGPIX® System to determine the antigen concentration from liquid samples with unknown concentrations. In detail, we describe a newly developed assay for determining production yields of Drosophila S2-produced Marburg virus (MARV) glycoprotein in insect-cell-culture-derived supernatant. The potential applications of this assay could extend to the quantification of viral antigens in fluids derived from both in vitro and in vivo models infected with live MARV, thereby providing additional applications for virological research.

The catabolic-to-anabolic shift seen in the canine osteoarthritic cartilage treated with knee joint distraction occurs after the distraction period.

Background: Cartilage regenerative mechanisms initiated by knee joint distraction (KJD) remain elusive. Animal experiments that are representative for the human osteoarthritic situation and investigate the effects of KJD at consecutive time points could be helpful in this respect but are lacking. This study investigated the effects of KJD on the osteoarthritic joint of dogs on two consecutive timepoints. Methods: Osteoarthritis was bilaterally induced for 10 weeks in 12 dogs using the groove model. Subsequently, KJD was applied to the right hindlimb for 8 weeks. The cartilage, subchondral bone and synovial membrane were investigated directly after KJD treatment, and after 10 weeks of follow-up after KJD treatment. Macroscopic and microscopic joint tissue alterations were investigated using the OARSI grading system. Additionally, proteoglycan content and synthesis of the cartilage were assessed biochemically. RT-qPCR analysis was used to explore involved signaling pathways. Results: Directly after KJD proteoglycan and collagen type II content were reduced accompanied by decreased proteoglycan synthesis. After 10 weeks of follow-up, proteoglycan and collagen type II content were partly restored and proteoglycan synthesis increased. RT-qPCR analysis of the cartilage suggests involvement of the TGF-ß and Notch signalling pathways. Additionally, increased subchondral bone remodelling was found at 10 weeks of follow-up. Conclusion: While the catabolic environment in the cartilage is still present directly after KJD, at 10 weeks of follow-up a switch towards a more anabolic joint environment was observed. Further investigation of this timepoint and the pathways involved might elucidate the regenerative mechanisms behind KJD. The Translational Potential of this Article: Further elucidation of the regenerative mechanisms behind KJD could improve the existing KJD treatment. Furthermore, these findings could provide input for the discovery or improvement of other joint regenerative treatment strategies.

Radiation exposure and mortality risk from CT and PET imaging of patients with malignant lymphoma.

OBJECTIVE: To quantify radiation exposure and mortality risk from computed tomography (CT) and positron emission tomography (PET) imaging with (18)F-fluorodeoxyglucose ((18)F-FDG) in patients with malignant lymphoma (Hodgkin's disease [HD] or non-Hodgkin's lymphoma [NHL]). METHODS: First, organ doses were assessed for a typical diagnostic work-up in children with HD and adults with NHL. Subsequently, life tables were constructed for assessment of radiation risks, also taking into account the disease-related mortality. RESULTS: In children with HD, cumulative effective dose from medical imaging ranged from 66 mSv (newborn) to 113 mSv (15 years old). In adults with NHL the cumulative effective dose from medical imaging was 97 mSv. Average fractions of radiation-induced deaths for children with HD [without correction for disease-related mortality in brackets] were 0.4% [0.6%] for boys and 0.7% [1.1%] for girls, and for adults with NHL 0.07% [0.28%] for men and 0.09% [0.37%] for women. CONCLUSION: Taking into account the disease-related reduction in life expectancy of patients with malignant lymphoma results in a higher overall mortality but substantial lower incidence of radiation induced deaths. The modest radiation risk that results from imaging with CT and (18)F-FDG PET can be considered as justified, but imaging should be performed with care, especially in children.

Diclofenac enhances allergic responses in a mouse peanut allergy model.

BACKGROUND: Diclofenac and other non-steroidal anti-inflammatory drugs (NSAIDs) interfere with cyclo-oxygenase-mediated synthesis of prostaglandins, resulting in the inhibition of inflammatory immune responses. In contrast, it is known that NSAIDs are able to induce gastrointestinal damage. OBJECTIVE: Our aim was to investigate whether NSAIDs are able to enhance sensitization or abrogate tolerance to food antigens. METHODS: Mice were exposed to diclofenac and sensitized to peanut using cholera toxin as a mucosal adjuvant. In a tolerance model, oral tolerance was induced via feeding of peanut 3 weeks before sensitization with peanut. Diclofenac was administered before peanut feeding. After 4 weeks, peanut-specific antibodies in the serum and cytokine production in the spleen were measured. Induction of intestinal damage after oral exposure with diclofenac and peanut + cholera toxin was examined microscopically. RESULTS: Diclofenac-exposed animals showed increased levels of peanut-specific IgG1, IgG2a and IgE in the serum compared with vehicle-treated animals. Furthermore, peanut-induced cytokine production in the spleen was elevated upon diclofenac treatment. Importantly, diclofenac did not induce peanut-allergic responses in the absence of the cholera toxin, although exposure to diclofenac and peanut + cholera toxin resulted in intestinal epithelial damage. Reduced peanut-specific antibody production in the case of oral tolerance was not reversed after diclofenac exposure. However, oral tolerance, as measured by inhibition of peanut-specific cytokine responses, was reverted by diclofenac. CONCLUSIONS: These data point towards an increased risk for induction of food-allergic responses by diclofenac, when other circumstances are also in favour of induction of allergy.

Effects of partial maize silage substitution with microalgae on viscosity and biogas yields in continuous AD trials.

The microalga Acutodesmus obliquus was investigated as a feedstock in semi-continuously fed anaerobic digestion trials, where A. obliquus was co-digested with pig slurry and maize silage. Maize silage was substituted by both 10% and 20% untreated, and 20% ultrasonicated microalgae biomass on a VS (volatile solids) basis. The substitution of maize silage with 20% of either ultrasonicated and untreated microalgae led to significantly lower biogas yields, i.e., 560 dm³ kg-1 VScorr in the reference compared to 516 and 509 dm³ kg-1VScorr for untreated and ultrasonicated microalgae substitution. Further, the viscosities in the different reactors were measured at an OLR of 3.5 g VS dm-3 d-1. However, all treatments with microalgae resulted in significantly lower viscosities. While the mean viscosity reached 0.503 Pa s in the reference reactor, mean viscosities were 53% lower in reactors where maize was substituted by 20% microalgae, i.e. 0.239 Pa s, at a constant rotation speed of 30 rpm. Reactors where maize was substituted by 20% ultrasonicated microalgae had a 32% lower viscosity, for 10% microalgae substitution a decrease of 8% was measured. Decreased viscosities have beneficial effect on the bioprocess and the economy in biogas plants. Nonetheless, with regard to other parameters, no positive effect on biogas yields by partial substitution with microalgae biomass was found. The application of microalgae may be an interesting option in anaerobic digestion when fibrous or lignocellulosic substances lead to high viscosities of the digested slurries. High production costs remain the bottleneck for making microalgae an interesting feedstock.

Faecal bacterial and short-chain fatty acids signature in hypercholesterolemia.

Gut microbiota has been suggested to affect lipid metabolism. The objective of this study was to characterize the faecal microbiota signature and both short chain fatty acids (SCFAs) and bile acids (BA) profile of hypercholesterolemic subjects. Microbiota composition, SCFAs, BA and blood lipid profile from male volunteers with hypercholesterolemia (HC) and normocholesterolemia (NC) were determined by 16S rDNA sequencing, HPLC, GC and NMR, respectively. HC subjects were characterized by having lower relative abundance of Anaeroplasma (0.002% vs 0.219%, p-value = 0.026) and Haemophilus (0.041% vs 0.078%, p-value = 0.049), and higher of Odoribacter (0.51% vs 0.16%; p-value = 0.044). Correlation analysis revealed that Anaeroplasma and Haemophilus were associated to an unfavourable lipid profile: they correlated negatively to cholesterol and triglycerides related biomarkers and the ratio total to high density lipoprotein (HDL) cholesterol, and positively to HDL size. Odoribacter displayed an opposite behaviour. Faecal SCFAs profile revealed higher abundance of isobutyric (2.76% vs 0.82%, p-value = 0.049) and isovaleric acid (1.32% vs 0.06%, p-value = 0.016) in HC. Isobutyric acid correlated positively with Odoribacter and lipid parameters indicative of an unfavourable profile. BA profile did not show differences between groups. It was concluded that HC subjects showed a particular faecal bacterial signature and SCFAs profile associated with their lipid profile.

Branched oligosaccharide structures on HBV prevent interaction with both DC-SIGN and L-SIGN.

Hepatitis B virus (HBV) is a DNA virus that infects the liver as primary target. Currently, a high affinity receptor for HBV is still unknown. The dendritic cell specific C-type lectin DC-SIGN is involved in pathogen recognition through mannose and fucose containing carbohydrates leading to the induction of an anti-viral immune response. Many glycosylated viruses subvert this immune surveillance function and exploit DC-SIGN as a port of entry and for trans-infection of target cells. The glycosylation pattern on HBV surface antigens (HBsAg) together with the tissue distribution of HBV would allow interaction between HBV and DC-SIGN and its liver-expressed homologue L-SIGN. Therefore, a detailed study to investigate the binding of HBV to DC-SIGN and L-SIGN was performed. For HCV, both DC-SIGN and L-SIGN are known to bind envelope glycoproteins E1 and E2. Soluble DC-SIGN and L-SIGN specifically bound HCV virus-like particles, but no interaction with either HBsAg or HepG2.2.15-derived HBV was detected. Also, neither DC-SIGN nor L-SIGN transfected Raji cells bound HBsAg. In contrast, highly mannosylated HBV, obtained by treating HBV producing HepG2.2.15 cells with the alpha-mannosidase I inhibitor kifunensine, is recognized by DC-SIGN. The alpha-mannosidase I trimming of N-linked oligosaccharide structures thus prevents recognition by DC-SIGN. On the basis of these findings, it is tempting to speculate that HBV exploits mannose trimming as a way to escape recognition by DC-SIGN and thereby subvert a possible immune activation response.

New Processes for Freeze-Drying in Dual-Chamber Systems.

Dual-chamber systems can offer self-administration and home care use for lyophilized biologics. Only a few products have been launched in dual-chamber systems so far-presumably due to dual-chamber systems' complex and costly drug product manufacturing process. Within this paper, two improved processes (both based on tray filling technology) for freeze-drying pharmaceuticals in dual-chamber systems are described. Challenges with regards to heat transfer were tackled by (1) performing the freeze-drying step in a needle-down orientation in combination with an aluminum block, or (2) freeze-drying the drug product "externally" in a metal cartridge with subsequent filling of the lyophilized cake into the dual-chamber system. Metal-mediated heat transfer was shown to be efficient in both cases and batch (unit-to-unit) homogeneity with regards to sublimation rate was increased. It was difficult to influence ice crystal size using different methods when in use with an aluminum block due to its heat capacity. Using such a metal carrier implies a large heat capacity leading to relatively small ice crystals. Compared to the established process, drying times were reduced by half using the new processes. The drying time was, however, longer for syringes compared to vials due to the syringe design (long and slim). The differences in drying times were less pronounced for aggressive drying cycles. The proposed processes may help to considerably decrease investment costs into dual-chamber system fill-finish equipment. LAY ABSTRACT: Dual-chamber syringes offer self-administration and home care use for freeze-dried pharmaceuticals. Only a few products have been launched in dual-chamber syringes so far-presumably due to their complex and costly drug product manufacturing process. In this paper two improved processes for freeze-drying pharmaceuticals in dual-chamber syringes are described. The major challenge of freeze-drying is to transfer heat through a vacuum. The proposed processes cope with this challenge by (1) freeze-drying the drug product in the syringe in an orientation in which the product is closest to the heat source, or (2) freeze-drying the drug product outside the syringe in a metal tube. The latter requires filling the freeze-dried product subsequently into the dual-chamber syringe. Both processes were very efficient and promised to achieve similar freeze-drying conditions for all dual-chamber syringes within one production run. The proposed processes may help to considerably decrease investment costs into dual-chamber syringe fill-finish equipment.

Expression of X-linked inhibitor of apoptosis as a novel prognostic marker in radically resected non-small cell lung cancer patients.

PURPOSE: To assess the pattern of expression and the prognostic value of the inhibitor of apoptosis family member X-linked inhibitor of apoptosis (XIAP; MIHA/ILP-a) in radically resected non-small cell lung cancer patients. EXPERIMENTAL DESIGN: The expression of XIAP and its relationship with overall survival was analyzed by immunohistochemistry on tumors from 144 patients with early-stage non-small cell lung cancer. In addition, the apoptotic and mitotic index, Ki-67, p53, and bcl-2 levels were also assessed. RESULTS: XIAP expression was specific for tumor cells, and the pattern was cytoplasmic. The median expression of XIAP was 20%, and when this value was used as a cutoff point for statistical analyses, 63 of the samples were considered high XIAP-expressing and 81 low XIAP-expressing. Surprisingly, high XIAP-expressing patients had a longer overall survival than the group expressing lower levels (60 versus 24 months of median survival; log rank, P = 0.01). The positive impact of XIAP expression on survival was confirmed by multivariate analysis (P = 0.026). Although no correlation was observed between XIAP expression and the apoptotic index, a significant inverse correlation was observed between XIAP, Ki-67 (P = 0.006), and mitotic index (P = 0.04). CONCLUSIONS: The unexpected inverse correlation of XIAP with proliferation markers and the absence of correlation with apoptotic index, coupled with its role as an independent positive prognostic factor for survival in radically resected NSCLC patients imply a more complex role for XIAP in tumor biology than anticipated by in vitro data.

Susceptibility of Acanthamoeba to soft contact lens disinfection systems.

Members of the genus Acanthamoeba are increasingly recognized as agents of indolent, chronic, infectious keratitis. Recently, Acanthamoeba corneal infection has been reported in some persons who wear soft contact lenses. In this study, three "heat" and three "cold" soft contact lens disinfection systems were tested according to the manufacturers' instructions against Acanthamoeba castellanii and Acanthamoeba polyphaga in separate trials, and with appropriate controls. Suspensions of Acanthamoeba cysts or trophozoites of each species were tested individually. Each of the three heat disinfection units killed all acanthamoebae in one cycle in all trials. A chlorhexidine 0.005%/thimerosal 0.001% solution killed A. castellanii trophozoites and cysts, but those of A. polyphaga survived. Trophozoites and cysts of both species survived an alkyl triethanol ammonium chloride 0.013%/thimerosal 0.002% solution and a hydrogen peroxide 3% preparation. Heat disinfection overall appears to be more effective in killing Acanthamoeba trophozoites and cysts as compared to cold disinfection methods.

Susceptibility of Acanthamoeba to cryotherapeutic method.

Acanthamoeba keratitis is becoming an increasingly well-known clinical entity. The Acanthamoeba species in their encysted state are resistant to antimicrobial agents, resulting in corneal infections that are refractory to medical therapy. Corneal cryotherapy has been used to treat Acanthamoeba keratitis with varying and equivocal success. We subjected trophozoites and cysts of two species of Acanthamoeba recovered from corneal infections to trials of in vitro freeze-thaw-refreeze cryotherapeutic methods. The trophozoites of both species were killed in all trials. However, the cysts of both species survived all trials. Cryotherapy may not be an effective means to eliminate Acanthamoeba cysts from the cornea.

Preoperative localization of the central sulcus by dipole source analysis of early somatosensory evoked potentials and three-dimensional magnetic resonance imaging.

Surgery of lesions within or close to the central area of the brain always carries the risk of iatrogenic motor or sensory deficits. Functional localization by means of intraoperative direct stimulation of the motor area or by recording somatosensory evoked potentials (SSEP's) from the surface of the somatosensory cortex is believed to reduce the operative risk. The authors introduce the combination of dipole source analysis of scalp-recorded SSEP's with three-dimensional (3-D) magnetic resonance (MR) imaging as a tool for preoperative localization of the central sulcus. This provides information on both functional and structural localization for preoperative planning. Four repeated measurements of right and left median nerve SSEP's were obtained from 20 subjects. Dipole source analysis showed a retest reliability of the 3-D localization error of 2.9 +/- 2.0 mm. Compared to the MR evaluation, dipole source analysis was found to mark the central sulcus within 3 mm for 15 conditions (subjects x side of stimulation), while the 3-D MR measurement was accurate to within 6 mm for 10 conditions and 9 mm for 14 conditions. Dipole locations were confirmed in six patients who underwent surgery of the central region. With respect to this application, dipole source analysis combined with 3-D MR imaging appears to be a valuable tool for preoperative functional localization. The accuracy in localization will be further improved when realistic head models become available that can take into account individual head geometry. Further development of the proposed new method holds promise that evoked potentials and electroencephalography will gain greater use in presurgical functional localization.

Scar remodeling after strabismus surgery.

PURPOSE: We sought to investigate abnormal scar lengthening after strabismus surgery. METHODS: Patients with overcorrection after strabismus surgery or undercorrection after extraocular muscle resection underwent exploration of previously operated muscles. Abnormal findings were documented by inspection and photography, and repair was undertaken at first with absorbable sutures and later with nonabsorbable sutures. RESULTS: Lengthened scars, consisting of amorphous connective tissue, were repaired on 198 muscles in 134 procedures by excision of the scar and reattachment of the muscle to sclera; absorbable sutures were used in 64 procedures, and nonabsorbable sutures were used in 70 procedures. Thirty-one procedures were followed by partial recurrence of the original overcorrection; 7 of these had documented restretching. The use of nonabsorbable sutures decreased the recurrence of strabismus from 42% to 6%. Factors that distinguished patients with stretched scars from patients with classic slipped muscles included minimal or no limitation of versions, less separation of the tendons from sclera, and thicker appearance of the scar segments. CONCLUSIONS: A lengthened or stretched remodeled scar between an operated muscle tendon and sclera may contribute to variability of outcome after strabismus repair, even years later. Definitive repair requires firm reattachment of tendon to sclera with nonabsorbable suture support.

Congenital central hypoventilation syndrome: ocular findings in 37 children.

BACKGROUND: Congenital central hypoventilation syndrome (CCHS) is a rare cause of central sleep apnea. Although ophthalmic abnormalities have been reported, the ocular findings have not been discussed in detail. METHODS: We examined or obtained the records of 37 children with CCHS. RESULTS: Twenty-seven patients were found to have abnormal pupils, most of which were miotic and reacted poorly to light. In 18 cases, the anterior surface of the iris was unusually smooth. Ten of the children with abnormal pupils also demonstrated light-near dissociation. Twenty had strabismus of various types, and 18 showed evidence of convergence insufficiency. CONCLUSIONS: The high incidence of strabismus, pupillary abnormalities, and convergence insufficiency may be a result of neurologic defects in the midbrain.

Long-term results of bifocal therapy for accommodative esotropia.

We studied the long-term course of 65 accommodative esotropes who required bifocals to maintain alignment at near. Average follow-up was 10.5 years. Forty patients (61.5%, group DC [bifocals discontinued]) were able to discontinue bifocal use after an average of 5.5 years wear. Twenty-five (38.5%) continued to wear bifocals (or a suitable alternative such as reading glasses), after an average 9.7 years of follow-up. Surgical correction of deteriorated accommodative esotropia was performed for 20 patients (50%) in group DC, and nine (36%) of those in group C[bifocals continued]. Surgery produced an average reduction in the accommodative convergence relationship (near esodeviation in prism diopters [pd] minus corrected distance measurement, AC/A) of approximately 10 pd in both groups. Surgical patients unable to discontinue bifocal wear began with a clinically higher AC/A than those in group DC. Non-surgical patients in group DC experienced spontaneous improvement of the AC/A over time (average, 6.2 pd). On average, this did not occur in those of group C. Average age of bifocal discontinuation was 9.7 years in surgical patients and 9.3 years in the non-surgical. Surgical patients had significantly lower hyperopia (+2.4 diopters [D]), than non-surgical (+3.5 D), and an earlier age of onset of bifocal wear (3.29 versus 4.64 years). Although bifocals may be successfully discontinued in a majority of patients at an average age of 9.5 years, a significant percentage require long-term wear, some, despite surgery. The only factor that predicted long-term bifocal wear was a relatively high AC/A.

Rate of deterioration in accommodative esotropia correlated to the AC/A relationship.

We analyzed the claim that accommodative esotropia tends to deteriorate with greater frequency if the accommodation convergence relationship (AC/A) is high. Records of 119 patients whose eyes were aligned with spectacles alone were studied. Their AC/A relationships were graded according to the difference between the distance and near measurements: normal included 0 to 9 prism diopters (delta) difference; grade 1 ranged from 10 to 19 delta difference; grade 2 from 20 to 29 delta difference; and in grade 3 the difference was 30 delta or greater. Deterioration is characterized by a nonaccommodative component of esotropia greater than 10 delta at distance becoming superimposed on the initial accommodative esotropia. Deterioration occurred in 7.7% of patients with a normal AC/A, 25% with grade 1 high AC/A, 44% with grade 2 high AC/A, and 52% with grade 3 high AC/A. Hypotheses were investigated using chi square, t-test, analysis of variance (ANOVA), and log linear analyses. Distributional differences were highly significant by chi square test (p = 0.001) with a rejection of the null hypothesis of no difference between the groups at the alpha = 0.05 level. An alternate analysis of average AC/A ratio in the deteriorated versus nondeteriorated patients was equally statistically significant by the t-test. Hypermetropia was significantly higher in the normal AC/A group. Multi-factor comparisons showed that time-to-deterioration, treatment delay, age of onset, and amblyopia were factors that did not relate significantly to the incidence of deterioration.

Low-dose methotrexate in the treatment of severe juvenile rheumatoid arthritis and sarcoid iritis.

OBJECTIVE: To assess the efficacy of low-dose oral methotrexate (MTX) therapy for children with severe iritis. METHODS: MTX in a weekly dose of 7.25 to 12.5 mg/m2 was administered orally to four patients (two with juvenile rheumatoid arthritis [JRA] and two with sarcoidosis) with severe iritis not adequately controlled by topical and systemic corticosteroid therapy. The treatment was initiated with half of the total dose and increased every 2 weeks until the final dose was reached. Iritis was graded from 0 to +4 according to the density of cells in the anterior chamber of the eye. RESULTS: There were three girls and one boy with a mean age of 10.5 years. Two patients were African American and two were Caucasian. The mean age at onset of iritis was 6 years. The mean duration of MTX therapy was 28.8 months. Significant improvement was noted in two of the four patients in ocular inflammation, demonstrated by reduction of cell density from +4 to +1. Two patients had a mild improvement of the iritis. However, corticosteroids were significantly reduced in all patients. One patient was completely off steroids within 30 months of MTX therapy. In the remaining three cases, the steroid dose was successfully tapered from 0.82 mg/kg/d to 0.15 mg/kg/d (mean doses) within a mean duration of 20 months. No side effects were observed with MTX therapy. CONCLUSION: Low-dose MTX therapy was effective and safe, and displayed steroid-sparing properties in four children with severe iritis.

Scar remodeling after strabismus surgery.

PURPOSE: Patients with overcorrected strabismus (and several patients with undercorrection after extraocular muscle resection) underwent exploration of previously operated muscles, with the intention of advancing their tendons to prevent the need for surgery on additional muscles. Unexpectedly, it was found that, in many cases, an elongated scar segment of variable length was interposed between the muscle and its insertion site on the sclera. Laboratory investigations were carried out to elucidate the underlying mechanism(s) and to create an animal model of the disorder. METHODS: Lengthened scars were repaired on 198 muscles during 134 procedures performed on 123 patients. The scars consisted of amorphous connective tissue interposed between the globe and normal tendon. Repair was accomplished by excision of the scar and reattachment of the muscle to sclera, using absorbable sutures in 64 cases and nonabsorbable sutures in 70 cases. Histopathologic examination was performed on 82 clinical specimens, and tissue culture studies were performed on 7 specimens. To develop an animal model, 10 New Zealand white rabbits underwent bilateral superior rectus resection. Half of the eyes received sub-Tenon's injections of collagenase over the operative site during weeks 2, 3, 5, and 6 postoperatively; the other half received saline solution injections on the same schedule. At 10 weeks, half the sites were studied histologically, and the other half underwent collagen creep analysis. In a second study, the use of absorbable versus nonabsorbable sutures was compared in the rabbit model. RESULTS: In the clinical cases, the mean length of the elongated scar segments was 4.2 mm. A total of 105 of the 134 repair procedures were judged successful. Thirty-one procedures resulted in recurrence of the original overcorrection; 7 of these had documented restretches. Factors that distinguished patients with stretched scars from patients with classic slipped muscles included minimal or no limitation of versions, less separation of the tendons from sclera, and thicker appearance of the scar segments. The use of nonabsorbable sutures in the repair procedure reduced the recurrence rate. Histologic examination of the clinical stretched scar specimens showed dense connective tissue that was less well organized compared with normal tendon. In the tissue culture studies, cells cultured from the stretched scar specimens grew rapidly and were irregularly shaped. A high-molecular-weight protein was identified in the culture medium. By contrast, cells cultured from normal tendon (controls) grew more slowly and regularly, stopped growing at 4 days, and produced less total protein than cultured stretched scar specimens. In the animal model studies, the collagenase-treated sites showed elongated scars with increased collagen between the muscle and the sclera, as well as increased collagen creep rates, compared with the saline-treated controls. The use of nonabsorbable sutures in collagenase-treated animal model surgery sites was associated with shorter, thicker scars compared with similar sites sutured with absorbable sutures. CONCLUSIONS: A lengthened or stretched, remodeled scar between an operated muscle tendon and sclera is a common occurrence and is a factor contributing to the variability of outcome after strabismus repair, even years later. This abnormality may be revealed by careful exploration of previously operated muscles. Definitive repair requires firm reattachment of tendon to sclera with nonabsorbable suture support.

Strabismus due to flap tear of a rectus muscle.

PURPOSE: To present a previously unreported avulsion-type injury of the rectus muscle, usually the inferior rectus, and detail its diagnosis and operative repair. METHODS: Thirty-five patients underwent repair of flap tears of 42 rectus muscles. The muscle abnormality was often subtle, with narrowing or thinning of the remaining attached global layer of muscle. The detached flap of external (orbital) muscle was found embedded in surrounding orbital fat and connective tissue. Retrieval and repair were performed in each case. RESULTS: Fourteen patients had orbital fractures, 7 had blunt trauma with no fracture, and 9 had suspected trauma but did not undergo computed tomographic scan. Five patients experienced this phenomenon following retinal detachment repair. Diagnostically, the predominant motility defect in 25 muscles was limitation toward the field of action of the muscle, presumably as a result of a tether created by the torn flap. These tethers simulated muscle palsy. Seventeen muscles were restricted away from their field of action, simulating entrapment. The direction taken by the flap during healing determined the resultant strabismus pattern. All patients presenting with gaze limitation toward an orbital fracture had flap tears. The worst results following flap tear repair were seen in patients who had undergone orbital fracture repair before presentation, patients who had undergone previous attempts at strabismus repair, and patients who experienced the longest intervals between the precipitating event and the repair. The best results were obtained in patients who underwent simultaneous fracture and strabismus repair or early strabismus repair alone. CONCLUSIONS: Avulsion-type flap tears of the extraocular muscles are a common cause of strabismus after trauma, and after repair for retinal detachment. Early repair produces the best results, but improvement is possible despite long delay.

Hemispheric asymmetries of early cortical somatosensory evoked potentials revealed by topographic analysis.

Scalp topography of the early cortical SEPs was analysed in 50 normal right handed subjects. The following hemispheric asymmetries of the potentials were found: 1) The maximal amplitude of N20 was located predominantly at the P electrode after right sided stimulation, but varied between the CP, P and O electrode after left sided stimulation. 2) The N20 amplitudes were higher after right sided stimulation in approximately 70% of the subjects and the P25 and N30 amplitudes were higher after left sided stimulation in again approximately 70% of the subjects. No side difference of amplitudes was found for the subcortical N14. The N20 amplitude and location asymmetries were attributed to an anatomical asymmetry of the somatosensory cortex.