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Biomedical subjects

D G Hall

Publications and source records attributed to D G Hall.

At least 19 recordsLinked to original sources
PubMed1997

Cardiac compartment-specific overexpression of a modified retinoic acid receptor produces dilated cardiomyopathy and congestive heart failure in transgenic mice.

Retinoids play a critical role in cardiac morphogenesis. To examine the effects of excessive retinoid signaling on myocardial development, transgenic mice that overexpress a constitutively active retinoic acid receptor (RAR) controlled by either the alpha- or beta-myosin heavy chain (MyHC) promoter were generated. Animals carrying the alpha-MyHC-RAR transgene expressed RARs in embryonic atria and in adult atria and ventricles, but developed no signs of either malformations or disease. In contrast, beta-MyHC-RAR animals, where expression was activated in fetal ventricles, developed a dilated cardiomyopathy that varied in severity with transgene copy number. Characteristic postmortem lesions included biventricular chamber dilation and left atrial thrombosis; the incidence and severity of these lesions increased with increasing copy number. Transcript analyses showed that molecular markers of hypertrophy, alpha-skeletal actin, atrial natriuretic factor and beta-MyHC, were upregulated. Cardiac performance of transgenic hearts was evaluated using the isolated perfused working heart model as well as in vivo, by transthoracic M-mode echocardiography. Both analyses showed moderate to severe impairment of left ventricular function and reduced cardiac contractility. Thus, expression of a constitutively active RAR in developing atria and/ or in postnatal ventricles is relatively benign, while ventricular expression during gestation can lead to significant cardiac dysfunction.

Animals↗
PubMed1997

Red bluebirds and black greenflies: preschoolers' understanding of the semantics of adjectives and count nouns.

Three experiments explored preschoolers' and adults' understanding of the distinctive semantic functions of adjectives (i.e., to name properties) and count nouns (i.e., to name object kinds). In Experiment 1, we modeled a familiar adjective (e.g., "blue") syntactically as either an adjective (e.g., "This is a blue one") or a count noun (e.g., "This is a blue") and applied it to a target object (e.g., a blue creature). In Experiments 2 and 3, we marked the adjective phonologically as either an adjective (e.g., "This is a blue bird") or a part of a count noun (e.g., "This is a bluebird") and applied it to a target object (e.g., a blue bluebird). In all experiments, participants then had to extend the expression they heard to either an object of a different kind with the same property as the target (e.g., a different creature or bird colored blue) or an object of the same kind with a different property (e.g., the same creature or bird colored red). Four-year-olds and adults, but not 3-year-olds, who heard the adjective version were more likely than those who heard the count noun version to choose the object with the same property. Thus, by the age of four years, children treated a word's lexical category, cued syntactically or phonologically, as a powerful cue to its meaning.

Adult↗
PubMed1997

Aortic arch anomalies associated with long gap esophageal atresia and tracheoesophageal fistula.

PURPOSE: The purpose of this study was to determine whether aortic arch anomalies are associated with long gap esophageal atresia and tracheoesophageal fistula (EA-TEF). METHODS: The authors performed a retrospective review of all infants who had EA-TEF from 1980 to 1996 at two pediatric surgery centers. Two hundred three infants who had EA-TEF were identified. RESULTS: Twelve infants were noted to have both long gap EA-TEF defined as a gap length greater than 3 cm and aortic arch anomalies. Of these 12, 7 had aberrant right subclavian arteries originating from the descending aorta. Four of the seven infants who had aberrant right subclavian artery (SCA) had gap lengths greater than 4 cm. All four had their fistulae divided initially through a right thoracotomy with primary repair performed at a later date. The remaining five infants who had long gap EA-TEF had right-sided aortic arch with aberrant left subclavian arteries. All five initially underwent exploration through the right chest. On discovery of the long gap EA and concurrent vascular anomaly, the thoracotomies were closed, and the infants underwent definitive repair of both their EA-TEF and their vascular anomaly through a left thoracotomy. CONCLUSIONS: The authors find that aortic arch anomalies are associated with long gap EA-TEF. Patients who have these two anomalies tend to have a long gap. Preoperative diagnosis of these anomalies may alter the timing and technique of surgical intervention. The embryogenesis of these vascular lesions may account for this more severe form of esophageal atresia.

Aorta, Thoracic↗
PubMed1997

Needle localization for thoracoscopic resection of small pulmonary nodules in children.

BACKGROUND: Children who have malignant disease and pulmonary nodules frequently need a tissue diagnosis to direct therapy. Computed tomography (CT)-guided needle localization and methylene blue marking allow thoracoscopic resection of nonvisible nodules. METHODS: Malignant disease was diagnosed in three patients aged 2, 2.5, and 11 years. Pulmonary nodules seen on chest CT, representing either metastatic disease or infection developed in each patient. All lesions were 1 to 2 cm deep to the pleural surface, precluding thoracoscopic visualization. A Homer mammographic needle was placed near the lesion using CT guidance under general anesthesia. The pleura overlying the lesion was also marked with methylene blue. Under the same anesthetic, patients went to the operating room where the lesions were thoracoscopically resected. RESULTS: Needle localization and methylene blue staining accurately localized the lesion in all cases. Thoracoscopic resection provided a diagnosis of metastatic disease or infection in all cases. There were no complications. CONCLUSION: CT-guided needle localization of pulmonary lesions deep to the pleural surface, is a safe, accurate method for allowing thoracoscopic resection in these children who would otherwise need open thoracotomy for diagnosis.

Biopsy↗
PubMed1996

Does posterior sagittal anorectoplasty in patients with high imperforate anus provide superior fecal continence?

The posterior sagittal anorectoplasty (PSARP) has become the primary surgical procedure for patients with high imperforate anus. Very few careful long-term follow-up studies have established the superiority of the PSARP procedure over other surgical repair techniques. The authors' goal was to evaluate the operation and to identify the factors associated with improved continence. The medical records, operative reports, and radiographs of 53 patients (46 male, 7 female) who underwent PSARP for high imperforate anus at Children's Hospital and Medical Center (CHMC) between 1982 and 1990 were reviewed retrospectively. Subjective follow-up data were collected by telephone questionnaire, assessing habits indicative of stool continence, and a "fecal continence score" (FCS) was calculated for each patient. A prospective, 7-day diary assessing similar patterns of fecal continence was completed by each patient's family. The mean age of the patients studied was 8.0 years, and the mean follow-up period was 6.8 years. The telephone questionnaire was completed for 48 patients (94%). Toilet training for bowel continence was successful in 20 patients (42%) and occasionally successful in another 20 patients (42%), but 8 patients (16%) had no awareness of impending stool. Forty-five (94%) were physically active, but 16 (33%) reported social problems related to offending odor. The mean fecal continence score for all patients was 3.0 +/- 1.4 (5=excellent, completely continent), which was nearly identical to published scores for the other types of surgical repair. The FCS did not improve with age. The parents' responses to the telephone questionnaire matched the results obtained from the prospectively collected continence diary data. The authors' results for PSARP in patients with high imperforate anus do not differ substantially from those achieved by other repair techniques. Previously cited prognostic factors such as fistula anatomy and sacral anomalies did not appear to alter the functional results in the authors' series. Aggressive postoperative bowel management should be anticipated in all patients who have high imperforate anus and may benefit those who otherwise would achieve less satisfactory continence.

Adolescent↗
PubMed1996

Diagnosis of right coronary artery to right atrial fistula in a dog using two-dimensional echocardiography.

A five-year-old boxer dog developed cardiac murmurs, complete heart block and cardiomegaly associated with vegetative bacterial endocarditis. Using two-dimensional echocardiography, vegetative lesions of the aortic valves and extension of the vegetations into the proximal right coronary artery and adjacent atrial septum were identified. The vegetation within the atrial septum appeared as a cavitated mass which protruded into the right atrium. Fistulae within the atrial septal vegetation permitting communication between the coronary artery and right atrium were observed with colour Doppler echocardiography. The dog died despite medical treatment. Post mortem examination confirmed the echocardiographic findings. Vegetative endocarditis with invasion into the right coronary artery and atrial septum producing fistulae and communication with the right atrium has not been reported previously in dogs. Doppler echocardiography proved useful in demonstrating the abnormal anatomy, intraluminal fistular blood flow and its communication with the right atrium.

Animals↗
PubMed1995

Repair of neonatal aortic coarctation.

From 1981 to 1991, 146 infants under 1 month of age underwent repair of aortic coarctation. Forty-two had isolated coarctation, 53 had associated ventricular septal defect, and 51 had complex cardiac defects. The principal mode of presentation was congestive heart failure. The mean age at operation was 10.6 days. The technique for repair was left subclavian artery flap angioplasty in 126, resection with end-to-end anastomosis in 14, and a variety of repairs in 6 patients. Concomitant pulmonary artery banding was performed in 62 patients. The overall hospital mortality rate was 11%, and there was a strong association with pre-existing renal failure. The mean aortic clamp time in survivors was 23.9 minutes; mean hospital stay was 13.4 days. Significant restenosis occurred in 16 patients (11%) with an incidence of 10% after subclavian artery flap angioplasty. Eleven patients have undergone reoperation, and 5 were managed successfully with balloon dilatation.

Anastomosis, Surgical↗
PubMed1994

Effect of the bisphosphonate risedronate on bone metastases in a rat mammary adenocarcinoma model system.

Risedronate (NE-58095) is a third-generation bisphosphonate with very potent antiresorptive activity but few toxic effects. The purpose of this work was to evaluate the effect of risedronate treatment on bone metastases produced in a rat breast cancer model. Berlin Druckrey IV rats inoculated with ENU1564 mammary adenocarcinoma cells were treated daily with risedronate or a saline placebo. Survival times, dictated by extraskeletal metastases (lung, heart, and brain), were not affected by risedronate treatment. Risedronate-treated animals had skeletal changes associated with decreased remodeling of bones undergoing endochondral ossification, most prominently affecting the appendicular skeleton. Despite the skeletal alterations induced by the treatment, the distribution of bone metastases throughout the surveyed skeletal sites was similar for treated and untreated animals. Bone metastases were enumerated in histologic sections of distal femur, spine, and skull. Tumor size was estimated from area measurements obtained from histologic lesions in distal femoral metaphyses and vertebral bodies. A greater number of treated rats had no bone metastases in any of the examined sections (30 versus 16.1% of untreated rats). Multiple bone metastases were observed less frequently in treated rats (33.3 versus 71% of untreated rats). Treated rats had fewer observed bone metastases in each examined site than untreated rats (p < or = 0.025). Mean tumor areas in femora and vertebrae were smaller in treated rats (p < or = 0.05), due to the less frequent presence of very large lesions. In untreated animals, osteoclasts appeared to be active at the tumor/bone interface and osseous structures were often completely replaced by expanding tumors. In contrast, metastases in treated animals caused less disruption of skeletal histoarchitecture. The apparent lack of osteoclastic activity and retention of bone within lesions suggested a decreased contribution of osteoclasts to the bone resorptive process. An in vivo immunohistochemical cell proliferation assay failed to reveal differences in the percentage of dividing tumor cells in bone metastatic sites in treated versus untreated animals. The results demonstrate significant effects of risedronate treatment on the incidence and size of observed skeletal metastases in this model.

Adenocarcinoma↗
PubMed1994

Characterization of brain and bone-metastasizing clones selected from an ethylnitrosourea-induced rat mammary carcinoma.

An animal model for breast cancer, brain and bone metastasis was developed using ENU1564, a cell line established from a metastatic mammary adenocarcinoma induced by N-ethyl-N-nitrosourea in a female Berlin-Druckrey IV rat. The original tumor isolate (designated FP1) spontaneously metastasizes to regional lymph nodes and lung following orthotopic inoculation into mammary fat pad (mfp) and metastasizes widely following left cardiac ventricle (LV) inoculation. From FP1, two sublines were selected from brain metastases (designated Br7-C5) or from slowly growing colonies in vitro (FP2-A11), then cloned and compared in assays of spontaneous and experimental metastasis. After inoculation of 10(5) cells into mfp, Br7-C5 formed large tumors at the inoculation site (9.4 +/- 3.3 g) and spontaneously metastasized to lung and lymph node by 55 days post-inoculation (dpi). In contrast, FP2-A11 produced much smaller tumors within mfp (0.6 +/- 0.3 g) and failed to metastasize by 55 dpi. Rats inoculated via the LV with 10(4) Br7-C5 cells developed signs of weight loss, head tilt, and dyspnea by 24 +/- 1.4 dpi with consistent colonization of brain, bone, lung, heart, kidney, and stomach. Rats inoculated similarly with FP2-A11 showed no signs until 53 +/- 12.3 dpi, when all developed rear limb paresis. There was significant colonization of only brain and bone, with only minor lung involvement. These ENU1564 sublines thus differ in their apparent rates of tumor growth and lesion development in vivo, their capacity to metastasize from orthotopic implantation sites, and in the spectrum of tissues colonized in experimental metastasis assays. Both clones provide reproducible models of breast cancer metastasis in syngeneic hosts, particularly to brain and bone.

Animals↗
PubMed1994

Intraoperative transesophageal echocardiography of coronary artery fistulas.

Coronary artery fistula is a rare abnormality but one with substantial surgical importance, as operation abolishes the fistulous shunt volume, progressive coronary dilatation, and potential coronary steal. Prior reports emphasize the utility of direct inspection on cardiopulmonary bypass, with visualization of drainage of blood or cardioplegia from the fistulous connection, to define the drainage site. We report 3 patients in whom intraoperative transesophageal echocardiography was used for precise localization of the fistulous drainage site, selective demonstration of vessels feeding the fistulas, and documentation of abolition of fistulous flow, all without need for cardiopulmonary bypass. In addition, the technique provides for continuous monitoring of ventricular function, providing the opportunity to detect inadvertent ischemic effects of ligation. This approach appears to have considerable utility.

Child, Preschool↗
PubMed1994

A new technique for surgical correction of bronchial stenosis.

Bronchial stenosis in children presents an even more challenging reconstructive procedure than does tracheal stenosis because of the smaller luminal diameter of the bronchus. Multiple techniques have been used, with varying success. Pericardium is readily available and can be used as a bronchial patch; however, it is floppy and tends to collapse, resulting in luminal narrowing and eventual scarring leading to restenosis. We devised a technique that uses glutaraldehyde-soaked pericardium with a rib cartilage stent to reconstruct the bronchus in two children who had main-stem bronchial stenosis.

Bioprosthesis↗
PubMed1994

How mothers teach basic-level and situation-restricted count nouns.

Recent research suggests that young children assume, as a default, that a word applied ostensively to an unfamiliar object (e.g. a man riding in a car) is a basic-level count noun (e.g. person) rather than a situation-restricted count noun (e.g. passenger). In this experiment, 14 mothers and their children (mean age 3.7; range 3.0 to 4.6) participated in a story-book reading session in which the mothers taught their children both a basic-level count noun and a situation-restricted count noun for a series of object drawings. An analysis of mothers' spontaneous teaching strategies revealed that, for a given object, they typically taught a basic-level count noun before a situation-restricted count noun. Furthermore, they tended to teach basic-level count nouns exclusively through ostensive definition, especially when the objects were unfamiliar. Moreover, they were (1) more likely to use ostensive definitions and (2) less likely to provide additional information concerning the application of the word, when teaching basic-level count nouns than when teaching situation-restricted count nouns. The results provide new evidence that word teachers, like young word learners, assume that a basic-level count noun is the psychologically-privileged candidate for an ostensive definition involving an (unfamiliar) object.

Child, Preschool↗
PubMed1994

Semantic constraints on word learning: proper names and adjectives.

4 experiments examined 3- and 4-year-olds' interpretations of novel words applied to familial objects in the sentence frame, "This Y is X," where X is a novel word, and Y is a familiar basic-level count noun (e.g., "dog," "cup"). These novel words are ambiguous and could be interpreted either as proper names (e.g., "Fred") or as adjectives/mass nouns (e.g., "red"/"lead"). The experiments addressed 2 questions. First, do children appreciate that the words can be construed either as proper names referring to individuals or as adjectives/mass nouns referring to salient properties/material kinds? The results showed that children could easily make either interpretation. Second, what factors affect children's tendency to make either a proper name or an adjective/mass noun interpretation? In the experiments, children learned the novel words for a range of animals and artifacts. Most children who learned the words for typical pets (e.g., a bird) made proper name interpretations, as did the majority of those who learned the words for certain non-pet animals (e.g., a caterpillar) described as possessed by someone, but only about half of those who learned the words for such non-pet animals not so described. Very few children who learned the words for either simple (e.g., a shoe) or complex (e.g., a boat) artifacts made proper name interpretations. The results provide clear evidence of the role of semantic information in constraining children's interpretation of a novel word, and they help to refine an understanding of what counts as a nameable individual for preschoolers.

Child Language↗
PubMed1994

Fatigue: a new approach to an old problem.

Previous research regarding the fatigued patient has dealt primarily with the diagnostic labels applied by physicians, rather than specific presenting symptoms of the fatigued patient. The purpose of the present study was to identify, based on presenting symptoms, gender, marital status, and race, relatively homogeneous sub-groups within a sample of fatigued patients that would aid in the diagnosis and treatment of the underlying disorder(s). Results of cluster analysis suggested the presence of an Organic, Anxiety, Depression, and Mixed Anxiety/Depression group within the sample of 197 fatigued patients. Significant differences among these four groups were found on 13 of the 15 symptoms included in the cluster analysis. The proportion of males, married patients, and white patients in the Organic Group was significantly greater than in the other three inorganic clusters as a whole. Positive or negative responses to these 13 symptoms can facilitate the diagnosis and treatment of the fatigued patient.

Adolescent↗
PubMed1993

Basic-level individuals.

In this experiment, 4-year-old children interpreted a novel count noun taught ostensively for an unfamiliar object as referring to a basic-level kind (such as PERSON or DOG) rather than to a kind that individuates its members by type of situation (such as PASSENGER or PUPPY). Because ostension does not distinguish a basic-level kind from a situation-restricted kind, this finding suggests that children assume, as a default, reference to a basic-level kind rather than to a situation-restricted kind when they hear a count noun applied to an unfamiliar object in an ostensive definition. The experiment shows that the assumption guides children's interpretation only if the object is unfamiliar, and if no specific information is available calling for a situation-restricted kind interpretation. The proposed word-learning assumption is critical to an understanding of the psychologically privileged manner of individuation, and therefore, of quantification (e.g., counting) involving objects.

Child Language↗
PubMed1993

Double aortic arch causing tracheoesophageal compression.

Since 1972, 17 patients have been surgically treated for double aortic arch at our institution. The procedure became necessary before 12 months of age in 11 patients and before 24 months in 16 patients. The major symptoms were respiratory distress, noisy breathing, and respiratory infections; four patients also had dysphagia. A high degree of clinical suspicion should warrant further investigation. Barium swallow and bronchoscopy were diagnostic and revealed extrinsic compression of the esophagus and trachea, respectively. Division of the anterior arch was performed in 16 patients; the right (posterior) arch was divided in the remaining patient. Kommerell's diverticulum was found in four patients and was resected in order to avoid recurrence of dysphagia by compression. A vascular suspension procedure was necessary in 13 patients to further release the trachea and esophagus. There was no mortality in this series, and symptomatic improvement was achieved in all patients. A degree of tracheomalacia may be responsible for some residual symptoms in four patients.

Adolescent↗
PubMed1993

The development of a linkage between count nouns and object categories: evidence from fifteen- to twenty-one-month-old infants.

Recent research suggests that, although young children appreciate many different kinds of conceptual relations among objects, they focus specifically on taxonomic relations in the context of word learning. However, because the evidence for children's appreciation of this linkage between words and object categories has come primarily from children who have made substantial linguistic and conceptual advances, it offers limited information concerning the development of this linkage. In the experiments reported here, we employ a match-to-sample task to focus specifically on the development of an appreciation of the linkage between words (here, count nouns) and object categories in infants in the period just prior to and just subsequent to the naming explosion. The results demonstrate that, for 21-month-old infants, most of whom have recently entered the vocabulary explosion (Experiment 1), and for 16-month-old infants, most of whom have yet to commence the vocabulary explosion (Experiment 2), novel nouns focus attention on taxonomic relations among objects. This is important because it reveals a nascent appreciation of a linkage between words and object categories in infants who are at the very onset of language production. Results are interpreted within a developmental account of infants' emerging appreciation of a specific linkage between count nouns and object categories.

Concept Formation↗