Search PubMed⌕ Search

Biomedical subjects

J L Marsh

Publications and source records attributed to J L Marsh.

At least 127 records · Page 7Linked to original sources
PubMed1994

Dorsal midline fate in Drosophila embryos requires twisted gastrulation, a gene encoding a secreted protein related to human connective tissue growth factor.

The twisted gastrulation (tsg) gene is one of seven known zygotic genes that specify the fate of dorsal cells in Drosophila embryos. Mutations in these genes cause at least some of the cells on the dorsal half of the embryo to adopt more ventral cell fates leading to the proposal that most of these genes participate in establishing, maintaining, or modulating a gradient of a single signaling molecule DECAPENTAPLEGIC (DPP). We have examined the effects of tsg mutations on the development of cuticule elements, expression of a region specific enhancer trap, and patterns of mitotic domains. Mutations of tsg only affect the fate of a narrow strip of dorsal midline cells and do not affect dorsal ectoderm cells. However, the pattern of tsg expression is not coincident with the territories affected by tsg mutations. Structural analysis of the tsg gene reveals features of a secreted protein suggesting an extracellular site of action. The TSG protein bears a weak resemblance to human connective tissue growth factor (CTGF), a TGF-beta-induced protein. We propose that dorsal midline cell fate is specified by the combination of both a TSG and a DPP signal to which the dorsal midline cells are uniquely competent to respond.

Algorithms↗
PubMed1994

Cartographic mapping of the skull from computed tomography scans.

Contemporary imaging technologies (i.e., computed tomography [CT] and magnetic resonance imaging) generate an overwhelming amount of data. Salient features from these data must be abstracted and presented to facilitate anatomical comprehension and imaging utility. Three-dimensional surface and volumetric reformations of CT data have extended the integration of high resolution CT data to the study and management of craniofacial deformities. Nonetheless, conventional displays of such imaging require multiple images to assess symmetry, sutural status, and traumatic disruption of the skull. We therefore devised a methodology to apply cylindrical cartographic mapping for display of the entire skull on 1 image. Cartographic mapping was used to evaluate the skulls of patients with congenital asymmetry due to hemifacial microsomia, craniosynostosis, and complex comminuted craniofacial fractures. Cartographic mapping does effectively display the entire skull in 1 image. Such images are useful to assess craniofacial symmetry, sutural status, and comminuted fractures. However, cartographic images cannot define anterior-posterior relationships, and they must be augmented with more traditional data displays for assessment of intermaxillary and jaw-cranial base relations.

Adult↗
PubMed1994

Binary nature and radiographic identifiability of craniosynostosis.

RATIONALE AND OBJECTIVES: Two independent gold standards and diagnoses from three-dimensional computed tomography (CT) images were used to examine the possibility that craniosynostosis is a binary abnormality that potentially may be diagnosed without error. METHODS: Surgical reports, histology of excised sutures, and three-dimensional CT images were compared for 25 children undergoing surgical management of craniosynostosis. Surgical reports identified sutures as normal or abnormal. Histology reported suture closure on a 5-point scale. Four radiologists used three-dimensional CT images to diagnose sutures on a 6-point rated response scale. RESULTS: Sutures with histology 0, 1, or 2 were normal on surgical reports, and those with histology 3 or 4 were abnormal. Most readers achieved nearly perfect sensitivity and specificity. Reader confidence was unrelated to degree of pathology. CONCLUSION: Craniosynostosis appears to be binary in our sample. Surgical reports, pathology results, and three-dimensional CT images read by experienced viewers achieved nearly perfect agreement.

Cranial Sutures↗
PubMed1994

Sphincter pharyngoplasty: a preoperative and postoperative analysis of perceptual speech characteristics and endoscopic studies of velopharyngeal function.

Perceptual speech and endoscopic evaluations were videotaped preoperatively and postoperatively for 20 patients who underwent sphincter pharyngoplasty. Randomized videotapes of these evaluations were rated by clinicians experienced in assessment of patients with velopharyngeal dysfunction. Results of perceptual speech ratings showed that nasal resonance following sphincter pharyngoplasty improved in 79 percent of patients (p = 0.006), frequency of nasal emission decreased in 74 percent (p = 0.018), and severity of emission decreased in 79 percent (p = 0.006). Rating of the overall change in speech quality was not statistically greater than chance (p = 0.41). Thirty percent of patients were judged to be hyponasal postoperatively, while none had been preoperatively. Results of endoscopic evaluations showed that 75 percent of patients had a quantitative decrease in orifice size (p = 0.013). Despite improved velopharyngeal function, 65 percent of patients were still considered candidates for additional surgical management postoperatively. While sphincter pharyngoplasty resulted in improved perceptual speech characteristics and velopharyngeal function, only 18 percent of patients showed complete resolution of hypernasality and nasal emission, and only 35 percent demonstrated complete velopharyngeal closure postoperatively.

Adolescent↗
PubMed1994

dishevelled is required during wingless signaling to establish both cell polarity and cell identity.

The dishevelled gene of Drosophila is required to establish coherent arrays of polarized cells and is also required to establish segments in the embryo. Here, we show that loss of dishevelled function in clones, in double heterozygotes with wingless mutants and in flies bearing a weak dishevelled transgene leads to patterning defects which phenocopy defects observed in wingless mutants alone. Further, polarized cells in all body segments require dishevelled function to establish planar cell polarity, and some wingless alleles and dishevelled; wingless double heterozygotes exhibit bristle polarity defects identical to those seen in dishevelled alone. The requirement for dishevelled in establishing polarity in cell autonomous. The dishevelled gene encodes a novel intracellular protein that shares an amino acid motif with several other proteins that are found associated with cell junctions. Clonal analysis of dishevelled in leg discs provides a unique opportunity to test the hypothesis that the wingless dishevelled interaction species at least one of the circumferential positional values predicted by the polar coordinate model. We propose that dishevelled encodes an intracellular protein required to respond to a wingless signal and that this interaction is essential for establishing both cell polarity and cell identity.

Amino Acid Sequence↗
PubMed1994

Effect of premature sagittal suture closure on craniofacial morphology in a prehistoric male Hopi.

Scaphocephaly is caused by premature sagittal suture closure. It restricts medial-lateral growth of the cranial vault which appears longer and narrower than normal. We examined how this natural malformation affected morphology of the cranial base and face. A prehistoric adult male Hopi with scaphocephaly was compared to 19 normal male Hopi (Old Walpi Series, Field Museum of Natural History, Chicago, IL). Three-dimensional coordinates of 53 landmarks were recorded on the cranial vault, cranial base, and face. Finite element scaling analysis was used to test for significant differences between the scaphocephalic and normal individuals in craniofacial morphology. Finite element scaling results indicated that scaphocephaly has a profound effect on cranial vault morphology. However, morphology of the cranial base and face were only slightly affected and, typically, are within the normal range of variation for the sample. An abnormality in the cranial base is not associated with scaphocephaly in this individual.

Arizona↗
PubMed1994

Craniofacial computer-assisted surgical planning and simulation.

Computer-assisted planning and simulation of craniofacial surgery has progressed from development, through validation, and into clinical use. CT scans are transferred from the radiology department to a graphics workstation in the surgeon's office or laboratory, where data postprocessing and visualization for anatomic evaluation and surgical simulation are performed. Quantitative and qualitative comparative analyses between the plan/simulation and the actual postoperative result provide the feedback that validates or refutes the preoperative assessment and simulated intervention. The optimum surgical solution can be chosen from many possibilities. Interactive computer-assisted surgical simulation is also useful for morbidity-free training of inexperienced surgeons.

Child↗
PubMed1994

Effect of shock wave treatment on femoral prosthesis and cement removal.

The present study has examined the efficacy of shock wave treatment to aid in the removal of bone cement in human cadaver femora after femoral prosthesis implantation. The shock waves were applied to the specimens at four points, in the circumference 90 degrees apart, at three levels. Four hundred shocks were applied at each point with intensity level of 25 kV. Extraction time of the bone cement was significantly (p < 0.002) faster in the treated versus untreated control groups. The average extraction time was decreased by 32%. Shock wave treatment also reduced the amount of residual cement inside the bone surface by an average of 55% (p < 0.006). The number of shocks needed to remove the prosthesis from bone cement also decreased significantly (p < 0.001) after shock wave treatment.

Aged↗
PubMed1994

Craniosynostosis: diagnostic imaging with three-dimensional CT presentation.

PURPOSE: To measure diagnostic performance and preference of two three-dimensional CT reconstruction modalities (voxel-gradient and surface-projection) displayed two ways (conventional and unwrapped) in craniosynostosis confirmed by surgical inspection and histologic analysis of resected sutures. METHODS: High-resolution 2-mm contiguous CT sections were obtained and three-dimensional reconstruction images generated for 25 infants and children with skull deformities before surgical treatment of craniosynostosis. Two pediatric radiologists and two neuroradiologists first ranked images by their own preferences for diagnostic use. Then they diagnosed craniosynostosis from images presented in random order and blinded. The standard of reference was inspection during surgery and histologic evaluation of excised sutures. Finally, reviewers repeated their subjective preference tests. RESULTS: The least experienced radiologist had 100% sensitivity for all imaging modalities and specificities ranging from 43% to 83%. The two most experienced radiologists performed nearly identically, with sensitivities of 96% and specificities of 100%. After performing diagnostic tasks using all image types, all radiologists preferred conventional surface projections. CONCLUSION: Experienced readers can achieve nearly perfect diagnostic performance using the latest three-dimensional CT reconstruction images, making it a contribution to the diagnostic process. Although performance is nearly identical for all modalities, readers strongly prefer conventionally presented surface-projection images.

Algorithms↗
PubMed1994

Effects of imposed hindfoot constraint on ankle contact mechanics for displaced lateral malleolar fractures.

Contact stress distributions on the tibial plafond were mapped in a series of eight fresh-frozen cadaver specimens in which displaced lateral malleolar fractures were studied. These included gripping (a) by snugly lacing the foot in an athletic shoe, (b) by polymethylmethacrylate potting of the calcaneus alone, and (c) by potting of the calcaneus plus talus. Each of these three gripping conditions was tested both for rigid and for nearly frictionless transverse external constraint conditions. Across the series, the grip-dependent changes in contact stress distributions were found to be very minor compared with the wide interspecimen variability that was consistently present. Moreover, although contact stresses generally increased with progressive lateral fibular fragment offsets of up to 5 mm, such an effect was far more modest than that seen in previous cadaver work. The present laboratory cadaver findings suggest that the contact stress elevations occurring clinically for displaced lateral malleolar fractures are probably relatively mild and likely not directly responsible for late secondary degeneration.

Ankle Injuries↗
PubMed1994

Does reduced hospital stay affect morbidity and mortality rates following cleft lip and palate repair in infancy?

Insurance carriers affected decisions regarding admissions and length of stay in our hospital in 1987. Charts were reviewed retrospectively to determine whether this affected morbidity and mortality rates following cleft lip and palate operations in infants. Two periods were studied: May of 1983 through April of 1987 (group I) and April of 1987 through May of 1991 (group II). A total of 248 infants with cleft lip and/or palate underwent 398 operations: lip adhesion (74), definitive lip repair (130), and palatoplasty (194). Half were performed in each period. Admission status, length of stay, length of operation, and short-term morbidity were documented. Morbidity included spontaneous and traumatic lip dehiscence, palatal dehiscence, and palatal fistula. Intergroup analysis was performed by the chi-squared method; p < or = 0.05 was statistically significant. In group I, 93 percent of patients were admitted before surgery. In group II, 5 percent were admitted before surgery and 79 percent the day of surgery. Hospital stay decreased nearly 2 days for each operation. There was no statistically significant difference between groups in distribution of operations, length of operations, or morbidity: lip surgery complications (p = 0.263), palatoplasty complications (p = 0.624). Reductions of hospital admissions and length of stay do not affect outcome of cleft lip and palate surgery in infants. The reduction in hospital days is equivalent to a savings of $138,000 (1991 dollars).

Ambulatory Surgical Procedures↗
PubMed1994

Segmental bone deficiency after acute trauma. The role of bone transport.

Bone transport, along with allied techniques of compression distraction, offer exciting new treatment alternatives for the difficult problem of segmental bone loss from acute trauma. Many factors must be considered before indicating these treatment methods, because it is clear that many of the problems that existed with more conventional methods also exist with these techniques. The indications for amputation vs. limb salvage must always be considered in these severe injuries. In less severe injuries with minimal bone loss and soft-tissue injury exposing well-vascularized segments of bone, traditional methods of stabilization, soft-tissue coverage, and grafting lead to more rapid healing times and return to function for patients. These techniques are reserved for the most severe type of injuries for which treatment times are long and complications not infrequent. Therefore, methods to speed treatment, avoid complications, and increase patient acceptance should be actively sought. The great advantage of these techniques is that the vast majority of the reconstruction is done on the injured limb segment, with minimal need for extensive donor-site defects.

Acute Disease↗
PubMed1994

Chronic infected tibial nonunions with bone loss. Conventional techniques versus bone transport.

Twenty-five patients with infected nonunions of the tibia and segmental bone loss were treated by one of two methods: resection and bone transport, or conventional treatment using less extensive debridement, external fixation, bone grafting, and soft-tissue coverage. The two groups were comparable except for gender distribution. Each group experienced similar rates of healing; eradication of infection; treatment time; final angulation; number of complications; and total number of surgical procedures. However, the final limb-length discrepancy was significantly less in the bone transport group.

Adult↗
PubMed1993

Comparative three-dimensional analysis of CT-scans of the calvaria and cranial base in Apert and Crouzon syndromes.

The purpose of this study is to describe and analyze Apert and Crouzon skulls from three-dimensional (3-D) reconstructions of CT-scans. 12 Apert patients and 19 with Crouzon syndrome were included in the study. The age range was 0 to 23 years. All CT-scannings were carried out according to the same protocol with a slice thickness of 2 or 4 mm and 3-D reconstructions of the craniofacial region included midsagittal and horizontal cuts. A number of qualitative characteristics of the calvaria and cranial base were recorded and the cranial base angle was measured on the 3-D models. Our results showed that Apert and Crouzon syndromes are very different in cranial development and their dysmorphology is highly age dependent. We suggest that cartilage abnormalities, especially in the anterior cranial base, play a primary role in cranial development in the Apert syndrome from very early intrauterine life. Several cranial anomalies observed postnatally, however, are caused by the resultant dysmorphic and compensatory growth and are probably compounded by early cranial deformation. The primary abnormality in Crouzon syndrome appears to be premature fusion of sutures and synchondroses. Based on the findings at birth and early infancy it would seem that such fusions occur relatively late in fetal life. The adult cranial form in Crouzon's patients is explainable by resultant dysmorphic and compensatory growth changes. Very early release of the coronal suture areas with advancement of the frontal bone is advocated in both syndromes but for somewhat different reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrocephalosyndactylia↗
PubMed1993

Vitelline membrane biogenesis in Drosophila requires the activity of the alpha-methyl dopa hypersensitive gene (I(2)amd) in both the germline and follicle cells.

The vitelline membrane of Drosophila eggs is composed of a family of proteins which are cross linked into an insoluble matrix with an overlying waxy layer that prevents desiccation. We present here three sets of experiments which show that integrity of the vitelline membrane requires the activity of the alpha methyl dopa hypersensitive (I(2)amdH or amd) gene in both egg chambers and follicle cells. We show that loss of amd activity either by dietary administration of inhibitors or in genetic mosaics of either the germ line or follicle cells leads to production of defective vitelline membranes and by in situ hybridization, that amd is expressed in both nurse cells and follicle cells. The amd gene product is the first non-structural protein gene described whose activity is required for vitelline membrane biosynthesis. Given its unique role in insects and its demonstrated sensitivity to dietary inhibitors, the amd gene product poses an attractive target for insect control.

Animals↗