Search PubMed⌕ Search

Biomedical subjects

J L Marsh

Publications and source records attributed to J L Marsh.

At least 109 records · Page 6Linked to original sources
PubMed1995

Developmental regulation of the alpha-methyldopa hypersensitive gene of Drosophila melanogaster.

The insect cuticle is a highly differentiated structure exhibiting considerable variety and specialization. Part of this specialization is achieved by regulating the nature and/or extent of sclerotization. The dopa decarboxylase (Ddc) and alpha-methyldopa hypersensitive (l(2)amd) genes of Drosophila are structurally related and it has been shown that the Ddc gene is required for the proper sclerotization of pigmented cuticle as well as for neurotransmitter production. The physiological role of the amd gene is unknown. Following the pattern of amd expression during development, we find that it is expressed in tissues that secrete clear flexible (arthrodial) cuticle both internally and in specialized external structures. We present electron microscopic evidence that loss of amd function leads to cuticle defects in a region of amd expression. We also find that amd is expressed in the larval CNS and ring gland where it may be involved in neurotransmitter metabolism similar to its paralog, Ddc. Lymph glands also express amd suggesting a possible role in the immune response. The expression of amd in segmentally repeating stripes at the end of dorsal closure suggests that amd may be a terminal target of the segmentation gene hierarchy which specifies segments.

Animals↗
PubMed1995

Functional conservation of the Wnt signaling pathway revealed by ectopic expression of Drosophila dishevelled in Xenopus.

Wnt genes encode secreted growth factors that exhibit potent effects on both embryonic and postembryonic development in vertebrates and invertebrates. Recently, the dishevelled (dsh), shaggy/zeste-white 3, and armadillo genes have been shown to participate in Wnt (wingless; wg) signaling in Drosophila. Vertebrate genes that have sequence similarities to all of these Drosophila genes have been identified. To determine whether these structurally conserved components of insect wg signaling represent a functionally conserved Wnt signaling pathway in vertebrates, we investigated the role of Drosophila dsh in Xenopus Wnt signaling. Xenopus embryos ectopically injected with Drosophila dsh mRNA developed duplicated axes similar to those seen in embryos injected with Wnt mRNAs. The involvement of dsh function in the Wnt signaling pathway in Xenopus was demonstrated using two assays which are specifically sensitive to Wnt signaling: synergistic induction of dorsal mesoderm with bFGF and the specific induction of a Wnt-responsive reporter gene. These findings support the notion that the intracellular response to the Wnt signal has been conserved during evolution to such an extent that its components may be interchanged between distantly related species.

Animals↗
PubMed1995

Articulated external fixation of pilon fractures: the effects on ankle joint kinematics.

The effect of the Orthofix articulated ankle external fixator on ankle and subtalar joint kinematics and fracture fragment motion was investigated in fresh cadaver specimens using biplanar radiographic analysis. The kinematic testing was performed for the normal ankle (i.e., no fixation) and for three alternate fixator hinge orientations. The fixator applications simulated a horizontal ankle axis (the current clinically preferred orientation), an axis coincident with a previously defined approximate ankle axis, and an axis located using a mechanical axis finder. The horizontal fixator application significantly disturbed normal ankle kinematics. Aligning the fixator hinge with an approximate ankle axis caused significant distortion of motion about only two of six possible rotational axes. Aligning the fixator hinge with the (specimen-specific) ankle axis determined by the axis finder most closely matched the motion of the normal ankle. For pilon fractures simulated by a transverse osteotomy, there appeared to be no physiologically significant fracture fragment motions, regardless of fracture stability or fixator orientation.

Ankle Injuries↗
PubMed1995

Major open injuries of the talus.

Seventeen patients with 18 open talar fracture-dislocations or total dislocations of the talus were reviewed to determine the functional outcome and incidence of infection. Seven of 18 feet (38%) developed infection. Infection was associated with extrusion of the talar body through the open wound (p < 0.025). Final follow-up was achieved in 13 of 17 patients (14 of 18 feet) at an average of 7 years and 4 months after injury. According to the Boston Children's Hospital ankle grading system, the overall results were considered excellent in one, good in five, fair in two, and failures in six feet. The data suggest a greater proportion of failures in the infected group compared with the non-infected group (p = 0.05).

Adolescent↗
PubMed1995

Transfusion requirements for craniosynostosis surgery in infants.

Retrospective review of the records of 73 consecutive young children who underwent craniosynostosis surgery between 1978 and 1992 in one center was conducted to determine transfusion requirements, to document morbidity, and to identify causative variables associated with transfusion. Operative age and weight, affected suture(s), craniofacial surgeon, neurosurgeon, anesthesiologist, preoperative and postoperative hematocrit, and transfusion volumes of blood and crystalline products were recoded. Transfusion volumes were converted to percent estimated red cell mass for analysis. Affected sutures were unicoronal (22), sagittal (17), bicoronal (11), multiple (11), metopic (10), and lambdoid (2). Mean operative age was 6.4 months. Mean preoperative hematocrit was 34 percent. Eighty percent of patients were discharged with hematocrit of 29 percent or greater. Discharge hematocrit was unrelated to year of surgery. Mean intraoperative transfusion was 72.1 +/- 56.6 percent estimated red cell mass. Transfusions differed statistically among suture(s), neurosurgeons, and anesthesiologists. Extensive cranio-orbital surgery for synostosis in young children does not produce excessive hemorrhage or transfusion morbidity. The anesthesiologist and neurosurgeon may be equally or more important than the affected suture(s) as causal variables in transfusion.

Blood Loss, Surgical↗
PubMed1995

Aesthetic considerations in extirpation of melolabial lymphatic malformations in children.

Surgical treatment of lymphatic malformations in the nasolabial region of children has produced disappointing results. Attempts to remove them through a preauricular incision have generally required a synchronous superficial parotidectomy in an attempt to prevent facial nerve injury. However, incomplete removal with this approach is common, leading to multiple surgeries, infections, facial nerve injury, and when parotidectomy is performed, a lateral facial concavity. To avoid these complications and still extirpate the lymphatic malformation, an alternative direct external technique has been employed since 1986. A retrospective review of nine children with melolabial lymphatic malformations so managed was undertaken to assess treatment outcome. All patients underwent computed tomography (CT) or, more recently, magnetic resonance imaging (MRI) scans to define the anatomic limits of the lymphatic malformation and its relationship to the facial musculature. Scans differentiated localized lesions (resectable) from diffuse lesions (unresectable). All patients underwent direct external soft-tissue excisional debulking by means of melolabial incisions with perialar and/or supra-white roll extensions as needed. The mean age at time of surgery was 5.6 years. Complications were considered minor: One patient developed a small hematoma for which no specific treatment was necessary; four patients required antibiotics for cellulitis. The mean age at follow-up was 5.25 years. The mean number of procedures necessary to achieve final outcome was 3.25. The mean number of episodes of postoperative cellulitis was 1.8. There was a high level of patient and parent acceptance of facial scars. No patient required secondary scar revision. The external approach addresses the pathology directly, removes a greater overall percentage of abnormal tissue than the traditional hemirhytidectomy approach, and avoids potential injury to the facial nerve and the deforming concavity resulting from parotidectomy.

Adolescent↗
PubMed1995

Revision of the failed sphincter pharyngoplasty: an outcome assessment.

This paper reports results of surgical management of failed sphincter pharyngoplasties that were performed for velopharyngeal dysfunction. Revisional surgery consisted of tightening of the sphincter pharyngoplasty port or reinsertion of sphincter pharyngoplasty flaps following dehiscence. We critique the anatomic abnormalities associated with unacceptable vocal resonance and nasal air escape following sphincter pharyngoplasty and analyze the effect of sphincter pharyngoplasty revision on ultimate speech outcome. The results of initial sphincter pharyngoplasty surgery were evaluated in 46 patients with velopharyngeal dysfunction. Nine (20 percent) of these patients were considered surgical failures because of persistent hypernasality and/or nasal turbulence on perceptual speech evaluation at least 3 months postoperatively. These patients underwent sphincter pharyngoplasty revision and form the basis of this report. All patients who failed sphincter pharyngoplasty initially underwent both preoperative and postoperative perceptual speech evaluations, lateral phonation radiographic studies with still reference views, and flexible nasendoscopic studies. Evaluations of upper airway status were conducted by the same experienced otolaryngologist. Following sphincter pharyngoplasty revision, 7 of 9 (78 percent) patients demonstrated resolution of velopharyngeal dysfunction, and to some degree, all patients managed with revision became hyponasal. The primary cause of failure was partial or complete flap dehiscence; a secondary cause was hypotonicity of the velopharyngeal mechanism. Failure was not correlated with the level of insertion of the pharyngoplasty flaps with respect to the point of attempted velopharyngeal contact. Sphincter pharyngoplasty is an effective means of management for velopharyngeal dysfunction in many patients. The objective of removing the stigmata of velopharyngeal dysfunction without causing upper airway obstruction may not be realistic in some patients with microretrognathia (i.e., Pierre Robin sequence), in whom anatomic constraints predispose to flap dehiscence. Problems with surgical technique contributing to failure appear to be related to experience of the surgeon, and improvement in outcome can be anticipated as the "learning curve" is overcome.

Child↗
PubMed1995

Evolutionary conservation of a cell fate specification gene: the Hydra achaete-scute homolog has proneural activity in Drosophila.

Members of the Achaete-scute family of basic helix-loop-helix transcription factors are involved in cell fate specification in vertebrates and invertebrates. We have isolated and characterized a cnidarian achaete-scute homolog, CnASH, from Hydra vulgaris, a representative of an evolutionarily ancient branch of metazoans. There is a single achaete-scute gene in Hydra, and the bHLH domain of the predicted gene product shares a high degree of amino acid sequence similarity with those of vertebrate and Drosophila Achaete-scute proteins. In Hydra, CnASH is expressed in a subset of the interstitial cells as well as differentiation intermediates of the nematocyte pathways. In vitro translated CnASH protein can form heterodimers with the Drosophila bHLH protein Daughterless, and these dimers bind to consensus Achaete-scute DNA binding sites in a sequence-specific manner. Ectopic expression of CnASH in wild-type late third instar Drosophila larvae and early pupae leads to the formation of ectopic sensory organs, mimicking the effect of ectopic expression of the endogenous achaete-scute genes. Expression of CnASH in flies that are achaete and scute double mutants gives partial rescue of the mutant phenotype, comparable to the degree of rescue obtained by ectopic expression of the Drosophila genes. These results indicate that the achaete-scute type of bHLH genes for cell fate specification, as well as their mode of action, arose early and have been conserved during metazoan evolution.

Amino Acid Sequence↗
PubMed1995

Management of the hypodynamic velopharynx.

Velopharyngeal dysfunction (VPD) resulting from an adynamic or hypodynamic velopharynx is an unusual pathology that poses vexing management problems for the Cleft Palate team. Correction of VPD has the potential for airway compromise. Endoscopically, this pathology is recognized by a large velopharyngeal (VP) gap size, which demonstrates little or no dynamic activity of the posterior or lateral pharyngeal walls nor of the velum in response to speech tasks or connected speech. Because of a paucity of literature defining the entity, a retrospective review of 175 patients who were treated for VPD at our center was undertaken. Analysis of management failures revealed an unexpected concentration of patients with hypodynamic or paretic VP mechanisms as documented by nasendoscopic assessments. A subpopulation of 41 (23%) patients with this characteristic was studied to define the patients at risk, to determine etiologic factors, and to critique intervention outcome among various surgical and nonsurgical managements. Results showed that the phenomenon of VP hypodynamism occurred more frequently in patients with submucous cleft palate (p = .014) and with VPD in association with malformation syndromes (p = .009) than in patients in other diagnostic categories. Conversely, VPD not associated with clefting occurred with greater frequency in the nonhypodynamic group than in the hypodynamic group (p = .002). Composite (surgical and prosthetic) primary management failure occurred in 42%. Between one and three procedures were necessary to achieve an acceptable speech result. We present a management algorithm and provide data regarding realistic expectations for various treatment outcomes in patients with this complex disorder, which have not, to date, been previously described.

Adolescent↗
PubMed1995

Spatial dysmorphology of the foot in Apert syndrome: three-dimensional computed tomography.

Computer assisted medical imaging was used to define the spatial dysmorphology of the foot in three patients with Apert syndrome and to correlate that dysmorphology with ambulation and footwear. Thin slice (2 mm), abutting, high resolution axial computed tomography (CT) foot scans were obtained. The CT data were post processed, using Analyze, to generate three-dimensional surface shaded and volumetric reformations. The reformatted images were evaluated by a bone and joint radiologist to identify abnormalities of bone shape, size, and orientation, of joint morphology, and of the foot as a whole. Five consistent findings were observed among the three pairs of feet: (1) anomalous great toes with phalangeal and metatarsal pathology; (2) simple syndactyly of toes 2-5; (3) fusions between matatarsals; (4) tarsal coalitions; and (5) limitations in commercial footwear. One patient underwent bilateral fifth metatarsal wedge osteotomies to facilitate the wearing of shoes. The dysmorphology of the Apert foot is a combination of congenital malformations and postnatal deformations, secondary to progressive synostosis. Prophylactic foot surgery may be indicated in Apert patients to facilitate shoe fitting.

Acrocephalosyndactylia↗
PubMed1995

Triopia: craniofacial malformation with prosencephalic duplication.

A case of ocular duplication with complex craniofacial and central nervous system anomalies is described. The anomaly is termed triopia because the child's most overt and distinguishing feature was three eyes: the left orbit contained two globes with independent ocular adnexa; the right orbit contained one normal appearing and functioning globe. Computer assisted medical imaging was used to define, in vivo, the intra- and extracranial soft and hard tissue anomalies: the cerebral hemisphere ipsilateral to the ocular duplication was also duplicated. Possible bases for this anomaly include duplication of primordia for the eye and secondary prosencephalon.

Abnormalities, Multiple↗
PubMed1995

Do palatal lift prostheses stimulate velopharyngeal neuromuscular activity?

The purpose of this investigation was to evaluate the ability of palatal lift prostheses to stimulate the neuromuscular activity of the velopharynx. Nasendoscopic evaluations were audio-videotaped preprosthetic and postprosthetic management for 25 patients who underwent placement of a palatal lift prosthesis for velopharyngeal dysfunction (VPD). These audio-videotapes were presented in blinded fashion and random order to three speech pathologists experienced in assessment of patients with VPD. They rated the tapes on the following parameters: VP gap size, closure pattern, orifice estimate, direction and magnitude of change, and qualitative descriptions of the adequacy of VP closure during speech. VP closure for speech was unchanged in 69% of patients and the number of patients rated as improved or deteriorated was nearly identical at about 15%. Postintervention gap shape remained unchanged in 70% of patients. The extent of VP orifice closure during speech remained unchanged in 57% of patients. Articulations that could impair VP function improved in 30% of patients, deteriorating in only 4%. Results of this study neither support the concept that palatal lift prostheses alter the neuromuscular patterning of the velopharynx, nor provide objective documentation of the feasibility of prosthetic reduction for weaning.

Adolescent↗
PubMed1995

External fixation and limited internal fixation for complex fractures of the tibial plateau.

Twenty-one complex fractures of the tibial plateau in twenty patients were treated with closed reduction, interfragmental screw fixation of the articular fragments, and application of a unilateral half-pin external fixator. The average duration of external fixation was twelve weeks (range, three to twenty weeks). The fixator was left in situ until the fracture had united in all but two patients. All of the fractures healed. The complications with this technique were attributable primarily to the proximal half-pins of the external fixator. Seven patients needed antibiotics for an infection at a pin site, and two had septic arthritis that necessitated arthrotomy and débridement. The average duration of follow-up was thirty-eight months. The range of motion of nineteen of the twenty-one knees was at least a 115-degree arc. Laxity was evident in seven knees, but no patient complained of instability of the knee. Radiographs showed malalignment of more than 6 degrees in three knees compared with the normal, contralateral knee and evidence of post-traumatic osteoarthrosis in five knees. The Iowa knee score, determined for nineteen patients, averaged 87 points (range, 55 to 100 points). The SF-36 general health survey demonstrated that most patients had function close to that of age-matched controls. We concluded that external fixation with limited internal fixation is a satisfactory technique for the treatment of selected complex fractures of the tibial plateau.

Adult↗
PubMed1995

Use of an articulated external fixator for fractures of the tibial plafond.

We performed a prospective study of forty-nine displaced fractures of the tibial plafond in forty-eight patients managed, at three centers, with an articulated external fixator placed medially across the ankle joint. Forty ankles had interfragmental screw fixation of a reduced articular fracture, and fourteen ankles had bone-grafting. The average duration of external fixation was twelve weeks. All of the fractures healed (one after delayed bone-grafting). There were no infections in any of the operative or traumatic wounds over the tibia. Two wound infections over the fibula resolved with treatment. Eight patients were managed with antibiotics for a pin-site infection, and two patients had curettage and débridement of a pin site in the hindfoot after removal of the fixator. Thirty patients (thirty-one ankles) completed two-year data sheets at an average of thirty months after the injury. The average ankle score was 67 points. Twenty-one patients had grade-0 or 1 osteoarthrosis and nine had grade-2 or 3. One ankle had been treated with an arthrodesis. These data suggest that the prevalence of early complications associated with severe fractures of the tibial plafond and their treatment can be decreased with use of an articulated external fixator combined with limited internal fixation. We concluded that this technique of external fixation is a satisfactory technique for the treatment of these fractures.

Adolescent↗
PubMed1995

Frontal plagiocephaly secondary to synostosis of the frontosphenoidal suture. Case report.

Frontal plagiocephaly may arise from either synostotic or deformational forces. Deformational causes of frontal plagiocephaly can be distinguished from synostotic causes by differences seen on physical examination, which can then be confirmed by skull x-ray films and if necessary three-dimensional computerized tomography (CT). Unilateral coronal synostosis is the main synostotic cause of frontal plagiocephaly, although it has also been seen with fusion of the frontozygomatic suture. In several syndromes presenting with bilateral coronal synostosis, fusion of the frontosphenoidal and frontoethmoidal sutures is also present. The authors report, for perhaps the first time, a case showing synostotic frontal plagiocephaly secondary to fusion of the frontosphenoidal suture alone. Although the phenotypic appearance is superficially similar to that seen in unilateral coronal synostosis, analysis of the cranial base shows markedly different effects: angulation of the anterior cranial base with respect to the posterior cranial base away from the synostotic side and angulation of the posterior cranial base with respect to the midpalatal suture also away from the synostotic side. In unilateral coronal synostosis, both angulations are toward the synostotic side. These effects on the cranial base alter its relationship to the cranial vault and the facial skeleton. Most important, frontal plagiocephaly secondary to fusion of the frontosphenoidal suture should not be overlooked as being deformational. Because this fusion is difficult or impossible to visualize by skull x-ray films, three dimensional CT must be obtained in cases that are not clearly identified as deformational plagiocephaly by physical examination.

Cranial Sutures↗
PubMed1995

Acetabular fractures classification of Letournel and Judet--a systematic approach.

After a background understanding of the classification of Judet and Letournel and the radiographic anatomy of the pelvis, the majority of acetabular fractures are readily classified by utilizing the steps as outlined above. We feel that a systematic, stepwise approach to classifying acetabular fractures into larger groups and then subclassifying these groups will help simplify the application of the Letournel and Judet classification. Try using this method, and your ability to classify these fractures will improve.

Acetabulum↗
PubMed1995

An articulated ankle external fixation system that can be aligned with the ankle axis.

Aligning an articulated ankle external fixator with the ankle axis located using a mechanical axis finder has been shown to preserve normal ankle joint kinematics while the fixed hinge device is attached. However, several problems exist preventing the clinical application of this finding for fractures of the tibial plafond. We initiated a series of studies to resolve these issues. First, the accuracy of the mechanical axis finder in biological systems was quantified by comparing it to that of a computationally derived helical axis. Second, a prototype fixator design was developed in the biomechanics lab to increase the versatility of intraoperative fixator placement. Finally, a radiographic method of locating the ankle axis was developed which is based on talar morphology independent of the fractured tibia. The prototype fixator has been accurately aligned along the ankle axis in cadaveric specimens using this method. Open reduction and internal fixation (ORIF) is the accepted method of treatment for tibial plafond fractures. It holds the advantage of sufficient fracture fixation to permit early joint motion. Good results have been reported using this method, but some authors have reported complication rates up to 50%. The wide surgical approaches required, in conjunction with preexisting soft tissue injury, are thought to significantly increase the risk of soft tissue complications. In response to these problems, many investigators are beginning to utilize external fixation as an alternate treatment modality. One external fixation system which has shown particularly good results is a monolateral cross-ankle articulated fixator (Orthofix SRL., Verona, Italy) which allows motion at the ankle joint as the plafond fracture is healing (Figure 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Ankle Joint↗