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Biomedical subjects

D G Hall

Publications and source records attributed to D G Hall.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1992

The dependence of lipid monolayer lipolysis on surface pressure.

Brönsted-Bjerrum theory [Brönsted (1922) Z. Phys. Chem. 102, 169-207; (1925) Z. Phys. Chem. 115, 337-364; Bjerrum (1924) Z. Phys. Chem. 108, 82-100] as applied to reactions at interfaces is used to interpret published data on the lipolysis of dinonanoyl phosphatidylcholine monolayers by pancreatic phospholipase A2. Reasonable quantitative agreement between theoretical and experimental results occurs when the reported effects of surface pressure on the amount of adsorbed enzyme are used together with the assumption that the Langmuir-Syskowski [Lange (1967) Nonionic Surfactants (Schick, M., ed.), chap. 4, Marcel Dekker, London and New York] isotherm describes the adsorption of lipid. The equations of Mass Action kinetics are less successful. Equivalent data on the lipolysis of didodecanoyl phosphatidylglycerol by pancreatic lipase can also be interpreted by arguing that the adsorbed enzyme forms significant amounts of enzyme substrate complex which reacts to give products in accordance with the well-known Briggs-Haldane [Lehninger (1975) Biochemistry, 2nd edn., chap. 8, Worth, New York] mechanism. The positions of the observed maxima in rate versus surface pressure plots suggests that the adsorption of an enzyme molecule displaces less lipid than one expects from the pronounced differences in molecular sizes of the two adsorbed species.

In Vitro Techniques↗
PubMed1992

Ultrasonographic characteristics of splenic and hepatic lymphosarcoma in three horses.

Splenic and hepatic ultrasonography were beneficial for diagnosis of lymphosarcoma in 3 horses with anorexia, weight loss, and lethargy. Ultrasonographic abnormalities of the spleen included a large, complex, hypoechoic mass in 1 horse, multiple well-marginated, hypoechoic nodules in 1 horse, and diffuse hyperechogenicity in another horse. Ultrasonographic abnormalities of the liver included a spherical, hypoechoic nodule in 1 horse and diffuse hyperechogenicity in another. Histologic examination of ultrasound-guided biopsy specimens or aspirates revealed lymphosarcoma. Necropsy findings confirmed diagnosis of lymphosarcoma in all horses. Necropsy findings of the liver and spleen correlated well with antemortem ultrasonographic images.

Animals↗
PubMed1992

Adenocarcinoma of the middle ear with osteolysis of the tympanic bulla in a cat.

Peripheral vestibular disease and lethargy were attributed to an adenocarcinoma in the middle ear of a 10-year-old cat. The tumor was invasive, inducing severe lysis of the tympanic bulla and adjacent temporal bone. Direct invasion to the meninges and brainstem also was observed. Neoplasms of the middle ear are rare in cats, with squamous cell carcinomas reported most commonly, but should be considered as causes of chronic otitis or signs of peripheral vestibular disease.

Adenocarcinoma↗
PubMed1992

Traumatic arteriovenous fistula: a complication of amniocentesis.

Fetal injury is a potential complication of amniocentesis. We report the case of an infant who had an isolated arteriovenous fistula between the popliteal artery and vein that resulted from amniocentesis. Unlike the usual congenital arteriovenous communications that are multiple and difficult to treat, this case was completely cured by division of the fistula and vascular repair. This case emphasizes that newborns and infants who have had invasive prenatal interventions such as amniocentesis should be identified and the possibility of fetal injury be considered when evaluating their clinical signs and symptoms.

Amniocentesis↗
PubMed1991

Neurologic manifestations of trypanosomiasis in a dog.

A 13-month-old Doberman Pinscher was evaluated because of slowly progressive paraparesis and signs of depression. The dog had temporal, supraspinatus, and infraspinatus muscle atrophy, bilateral enophthalmos, superficial inguinal lymphadenopathy, tachycardia with pulse deficits, and lesions of active and inactive chorioretinitis. Neurologic abnormalities included hyperreflexic patellar reflexes, lack of conscious proprioception, signs of superficial pain in the hind limbs, and depressed hopping reflexes in the forelimbs. Cranial nerve abnormalities included decreased sensation in the left nostril and a delayed gag reflex. Results of cerebrospinal fluid analysis were characteristic of nonsuppurative inflammation. A diagnosis of multifocal neurologic disease was made. The dog did not have serum titers for fungal diseases, canine distemper, Ehrlichia canis infection, borreliosis, Rocky Mountain spotted fever, or toxoplasmosis. The dog did not respond to various antimicrobial treatments, and only slightly responded to corticosteroid treatment. The dog died during an anesthetic procedure. The postmortem diagnosis of Trypanosoma cruzi infection (canine Chagas disease) was made on identification of the amastigote form of the organism in sections of brain, spinal cord, and myocardium.

Animals↗
PubMed1989

Staged repair of interrupted aortic arch with ventricular septal defect compared with primary repair in infancy.

Interrupted aortic arch is a poor prognosis cardiac anomaly with nearly 100 percent mortality if not recognized and treated early. The associated intracardiac lesions often lead to death if only the arch defect is repaired. Several recent reports have described patients with interrupted aortic arch who were treated as infants by primary repair of the arch defect with simultaneous repair of the intracardiac lesions. The improved survival data from these series have been attributed to the simultaneous repair of both lesions. We report herein on nine patients with both interrupted aortic arch and ventricular septal defect seen at Children's Hospital and Medical Center in Seattle from 1979 to 1987. Three patients had partial expression of DiGeorge's syndrome. All patients underwent primary repair of the interrupted aortic arch with concomitant pulmonary artery banding during infancy (mean age 18 days, range 2 days to 4 months). Operative mortality was 11 percent (1 of 9 patients). Eight patients had eventual repair of the ventricular septal defect (mean age 18 months, range 6 to 29 months) with one death occurring at 5 months postoperatively (12 percent mortality). The overall mortality of these nine patients was 22 percent. Staged repair of interrupted aortic arch with associated ventricular septal defect can be performed with results comparable to simultaneous primary repair in infancy. The improved survival from either approach is more likely to be attributable to improved perioperative stabilization, particularly the use of prostaglandin E.

Age Factors↗
PubMed1989

Seasonality of ovulation and estrus in Border Leicester ewes.

The number of Border Leicester ewes ovulating and their ovulation rate at 4 to 6 week intervals over 1 year and again after a further year were determined. The proportion of these ewes expressing estrus from autumn to spring and then in late summer/autumn was also determined. None of the ewes ovulated from October to early February, but for the remainder of the year, ovulation rate was always above 1.60, peaking in April to June at over 2.0. Eighty-four percent of the ewes had commenced ovulating by early March. The breeding season continued to September, when 10% of the ewes ovulated, with 25% expressing estrus in August and September. There was no significant effect of age, ewe liveweight or liveweight change on the proportion of ewes ovulating and their ovulation rate. The variability in the length of the breeding season gives scope for further selection.

Journal Article↗
PubMed1986

Seasonality of ovulation and estrus, and the ram effect in poll dorset ewes.

The effects of month on the proportion of Poll Dorset ewes expressing estrus and ovulating and on their ovulation rate when continually exposed to vasectomised rams and the effects of isolating the ewes from rams in winter/early spring were examined during 15 months in New South Wales, Australia. The percentage of ewes ovulating and their ovulation rate varied from 23% and 1.10 in November to an average of 99% and 1.85 in April and June, and the proportion of ewes expressing estrus followed a similar trend. Some ewes (6.8%) ovulated throughout the 15 months, and the average breeding season was 294 (SE = 6.1) days. Isolating ewes from rams in late winter/early spring significantly decreased the proportion of ewes ovulating from September to November, increased the proportion in December, but did not significantly alter ovulation rate. The variability in reproductive measures during spring offers scope for selection; with the ram effect, improvements in spring joining results from Dorset ewes are possible.

Journal Article↗
PubMed1986

Surgical repair of anatomically corrected malposition of the great arteries.

Anatomically corrected malposition of the great arteries is a rare malformation in which the aorta and pulmonary artery arise from their appropriate ventricles but in an abnormal spatial relationship. This report describes 2 patients with anatomically corrected malposition who underwent closure of a ventricular septal defect and placement of a right ventricle-pulmonary artery conduit. A review of the literature indicates that surgical results have been good (92% survival) in those patients with situs solitus and atrioventricular concordance [S,D,L]. However, when there is atrioventricular discordance, that is, [S,L,D] or [I,D,L], hypoplastic right heart structures, or both conditions, the outcome after palliative procedures has been poor (29% survival). The results of surgical treatment should improve as this entity is recognized earlier and prompt surgical treatment is undertaken.

Adolescent↗
PubMed1986

Healing basis and surgical techniques for complete revascularization of the left ventricle using only the internal mammary arteries.

Long-term follow-up data from several leading centers concerning patients undergoing coronary artery bypass clearly demonstrate the superiority of the internal mammary artery (IMA) with patency rates of 83 to 94% at 7 to 12 years compared with the saphenous vein and its patency rates of 41 to 53%. Our experimental studies provide a biological basis for understanding this difference. Thin-walled arterial autografts undergo no histological change after being implanted in the arterial system, while venous autografts undergo major changes with an initial scattered loss of endothelium and marked thickening due to a proliferative reaction. The challenge to the cardiac surgeon is to revascularize the entire left ventricle with the IMAs. We have found this possible in most patients with advanced three-vessel disease by using both IMAs either as in situ grafts or free grafts with as many sequential anastomoses as necessary to achieve full revascularization. Our use of the term in situ refers to the graft's origin from the subclavian artery as opposed to a free IMA graft arising from another site.

Aged↗
PubMed1986

A five- to seven-year experience with externally-supported Dacron prostheses in axillofemoral and femoropopliteal bypass.

We have examined the clinical results of 56 externally-supported (EXS) Dacron grafts in the axillofemoral position and 117 in the femoropopliteal position. Results have been analyzed from two perspectives: primary patency concerns only those grafts that had never occluded; extended patency refers to all open grafts including those whose continued patency is the result of thrombectomy. The 5-to 7-year life-table patency rates are: axillofemoral 8 mm and 6 mm bypass: primary 75% and extended 97%; above-knee femoropopliteal 6 mm bypass: primary 78% and extended 93%; below-knee 6 mm femoropopliteal bypass: primary 41% and extended 91%. In contrast, the results for the 5 mm grafts used for femoropopliteal bypass were inferior to the 6 mm grafts: femoropopliteal 5 mm bypasses had an above-knee primary patency rate of 44% and an extended rate of 55%, with a below-knee primary patency rate of 15% and an extended rate of 32%. Rendering the noncrimped porous Dacron prosthesis kink and compression resistant by an external support coil appears to increase its potential for successful use, especially in 8 mm axillofemoral and 6 mm femoropopliteal bypasses.

Actuarial Analysis↗
PubMed1985

Thrombolytic therapy for delayed occlusion of knitted Dacron bypass grafts in the axillofemoral, femoropopliteal and femorotibial positions.

Selective intra-arterial streptokinase therapy successfully reopened ten axillofemoral and lower extremity Dacron bypass grafts that had undergone delayed closure from two to 47 months after implantation. In four, completion arteriograms revealed no runoff obstruction acquired since implantation; additional runoff obstruction had developed in the remaining six. All of the grafts without obstruction have remained open from two to 11 months. Three of the six grafts with obstruction have remained open from two and one-half to four months after specific surgical correction of the obstructive lesion. We conclude that intra-arterial streptokinase therapy is an effective means to reopen knitted Dacron grafts that have undergone delayed closure in the axillofemoral and above-knee femoropopliteal positions.

Aged↗
PubMed1985

Tetralogy of Fallot: selective staged management.

One hundred twenty-four patients with tetralogy of Fallot have undergone either primary total repair (61), shunt and later repair (30), or an initial shunt (33). The mean ratio of pulmonary anulus to descending thoracic aorta increased from 0.80 +/- 0.25 before the shunt to 1.22 +/- 0.26 before the repair (p less than 0.0001). The mean ratio in the primary repair group was 1.23 +/- 0.25. A transannular patch was necessary in only six of 91 patients (6.6%). Postrepair right ventricular/left ventricular pressure ratio averaged 0.50 +/- 0.11 in the shunt plus repair group and 0.43 +/- 0.12 in the primary repair group. Only four patients had a right ventricular/left ventricular pressure ratio less than 0.65. A significant inverse linear relationship existed between this ratio and the pulmonary anulus size measured at operation and normalized for the patient's height (p less than 0.01). Postoperative complications occurred in 21% of patients after a shunt and 20% of patients after open heart repair. The early mortality was 0.8% (1/124). An initial shunt in patients with a small pulmonary anulus can result in an increased anulus size and better hemodynamic result with frequent avoidance of a transannular patch. Staged repair may result in improved overall mortality rates.

Child, Preschool↗