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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 595 records · Page 33Linked to original sources
PubMed1996

The coronary arteries in hearts with discordant atrioventricular connections.

Gross morphologic study of 14 hearts with congenitally corrected transposition or discordant atrioventricular connections and double-outlet right ventricle or pulmonary atresia disclosed consistently the origins of the coronary arteries from two aortic sinuses. With usual atrial arrangement, the artery arising in sinus 1 (right-hand facing), as seen from the noncoronary aortic sinus, supplied the morphologically right ventricle. Coronary blood supply to the morphologically left ventricle usually came from sinus 2 (left-hand facing), although in two hearts the circumflex branch was a continuation of the artery from sinus 1. The sinus nodal artery arose from the circumflex coronary artery, and histologic studies of two hearts demonstrated that blood supply to the anterior atrioventricular node also came from this vessel. Early branching and entrapment in fat or right ventricular muscle, as well as malalignment of aortic and pulmonary sinuses, occurred frequently. These findings may have implications for coronary arterial transfer in the double switch operation in hearts with discordant atrioventricular connections.

Adolescent↗
PubMed1996

Mutations associated with carcinomas arising from pleomorphic adenomas of the salivary glands.

Pleomorphic adenoma (PA) is the most common benign tumor of salivary glands. Carcinomas in pleomorphic adenomas (CPAs) may arise by malignant transformation of the epithelial components of PAs. Occasionally, transitional zones containing cells with histological features intermediate between those of the benign PA and carcinomatous components of CPA are identified. After careful microdissection of archival microslides, the authors studied 12 cases of CPAs and their attendant adenomatous and transitional areas for mutations in the p53, RB, and K-ras genes, and at chromosomal loci 5q and 9p. The authors failed to find mutations in the K-ras gene or 9p locus. A relatively high rate of mutations (loss of heterozygosity [LOH] and microsatellite alterations) at the p53 gene were detected in CPAs (58%), and at somewhat lower frequencies at the RB gene (33%) and chromosomal location 5q (17%). Mutational frequency in the associated transitional and adenomatous areas were slightly lower than in the corresponding CPAs. No mutations were detected in adenomatous or transitional areas unless they also were present in the corresponding CPAs. Mutations of these three genes were absent in four cases of CPA, and in seven PAs without malignant change. These findings indicate that most CPAs arise from adenomas as the result of mutations in the three genes, especially p53. In addition, other, as yet unidentified genes may also be involved both in the development of PA and in its malignant progression to CPA. Mutational analysis of PAs may provide information of prognostic importance.

Adenocarcinoma↗
PubMed1996

Self-care limitations of persons after acute myocardial infarction.

In this descriptive study, the self-care limitations of persons who had experienced their first myocardial infarction were identified during the first 3 months of their convalescent period. The five most frequently occurring limitations identified were patterns of personal and family living that interfere with self-care; intense emotional states, likes or dislikes, overriding interest and concerns; perceptions, meanings, and appraisals not in accord in reality; inability to attend to self with respect to changing conditions; and new, unrecognized requirements for self-care associated with changed health. Assessment of limitation is a framework that nurses might use to evaluate the needs of post myocardial infarction patients.

Adult↗
PubMed1996

Development of a national clinical logbook system for oral and maxillofacial surgery trainees--the RACDS, OMS system.

The development of a national computer database for trainees' clinical logbooks is described. Data are collected contemporaneously by trainees under the supervision of the director of their training programme. The full scope of oral and maxillofacial surgery is covered, and a national standard of experience has been developed. The benefits of this system to individual trainees, training institutions, and national educational bodies are presented.

Australia↗
PubMed1996

Why is there no diploid overdose effect in Prader-Willi syndrome due to uniparental disomy?

Due to DNA technology, it is now apparent that the mechanisms of genetic disease are more complex than the model of a gene with biallelic expression in the diploid state. If a gene is imprinted, monoallelic expression is the norm when the chromosomes of a pair are inherited normally from each parent. Uniparental disomy (UPD) is the abnormal situation where both chromosomes of a pair come from the same parent. When the chromosome contains an imprinted gene, UPD may result in nullisomy or disomy for a functional copy of that gene. If there are two imprinted loci on the same chromosome, UPD for that chromosome results in nullisomy for one imprinted gene but functional disomy for the other a "diploid overdose" (DO). This situation has been well demonstrated in the Prader-Willi syndrome (PWS) which is the nullisomic phenotype for the PWS gene(s) on chromosome 15q11-13. Chromosome 15q11-13 also contains the gene for Angelman syndrome (AS) which has a phenotype distinct from PWS. Both loci are subject to imprinting--in PWS, the imprint is on the maternal chromosome 15, in AS it is on the paternal chromosome 15. All individuals with PWS due to maternal UPD, while functionally nullisomic for the PWS locus, are functionally disomic for the AS locus--a DO situation. Assuming that biallelic expression of an imprinted gene is harmful, one would expect DO for an imprinted gene to produce a phenotypic effect. Cases of PWS due to UPD do not appear to differ from those due to deletion (hypopigmentation in deletional cases can be explained by loss of D15S12 downstream from the critical region). There is no good evidence of DO for the AS locus in PWS due to UPD. Why then was it 'necessary' in evolutionary terms to imprint the AS locus and maintain the imprint faithfully for life. A similar situation of two imprinted genes on the same chromosome occurs with IGF2 and H19 on chromosome 11p15. Maternal imprinting for IGF2 and paternal imprinting for H19 is the norm. Paternal UPD in this situation does lead to a DO effect, namely Beckwith-Wiedemann syndrome. The possibility of a DO effect needs to be considered when assessing the phenotypic spectrum of UPD for other chromosomes currently under investigation.

Animals↗
PubMed1996

Effect of perspective taking on the cognitive representation of persons: a merging of self and other.

Two experiments examined the possibility that perspective taking leads observers to create cognitive representation of others that substantially overlap with the observers' own self-representations. In Experiment 1 observers receiving role-taking instructions were more likely to ascribe traits to a novel target that they (observers) had earlier indicated were self-descriptive. This pattern was most pronounced, however for positively valenced traits. In Experiment 2 some participants received role-taking instructions but were also given a distracting memory task. In the absence of this task, role taking again produced greater overlap--primarily for positive traits--between self- and target representations. In the presence of the memory task, the degree of self-target overlap was significantly reduced for all traits, regardless of valence. Possible explanations for these findings are discussed.

Adult↗
PubMed1996

Susceptibility to multiple cutaneous basal cell carcinomas: significant interactions between glutathione S-transferase GSTM1 genotypes, skin type and male gender.

The factors that determine development of single and multiple primary cutaneous basal cell carcinomas (BCCs) are unclear. We describe a case-control study firstly, to examine the influence of allelism at the glutathione S-transferase GSTM1 and GSTT1 and cytochrome P450 CYP2D6 loci on susceptibility to these tumours and, secondly, to identify interactions between genotypes and relevant individual characteristics, such as skin type and gender. Frequency distributions for GSTM1 genotypes in cases and controls were not different, although the frequency of GSTM1 A/B was significantly lower (P = 0.048) in the multiple BCCs than in controls. We found no significant differences in the frequencies of GSTT1 and CYP2D6 genotypes in cases and controls. Interactions between genotypes were studied by comparing multinomial frequency distributions in mutually exclusive groups. These identified no differences between cases and controls for combinations of the putatively high risk GSTM1 null, GSTT1 null, CYP2D6 EM genotypes. Interactions between GSTM1 A/B and the CYP2D6 PM and GSTT1-positive genotypes were also not different. Frequency distributions of GSTM1 A/B with CYP2D6 EM in controls and multiple BCCs were significantly different (P = 0.033). The proportion of males in the multiple BCC group (61.3%) was greater than in controls (47.0%) and single BCC (52.2%), and the frequency of the combination GSTM1 null/male gender was significantly greater in patients with multiple tumours (P = 0.002). Frequency distributions of GSTM1 null/skin type 1 were also significantly different (P = 0.029) and the proportion of subjects who were GSTM1 null with skin type 1 was greater (P = 0.009) in the multiple BCC group. We examined the data for interactions between GSTM1 null/skin type 1/male gender by comparing frequency distributions of these factors in the single and multiple BCC groups. The distributions were almost significantly different (exact P = 0.051). No significant interactions between GSTT1 null or CYP2D6 EM and skin type 1 were identified. Comparisons of frequency distributions of smoking with the GSTM1 null, GSTT1 null and CYP2D6 EM genotypes identified no differences between patients with single and multiple tumours.

Aged↗
PubMed1996

Activity of intrinsic laryngeal muscles in fluent and disfluent speech.

The goal of the present experiment was to determine if stuttering is associated with unusually high levels of activity in laryngeal muscles. Qualitative and quantitative analyses of thyroarytenoid and cricothyroid recordings from 4 stuttering and 3 nonstuttering adults revealed the following: Compared to periods of fluent speech, intervals of disfluent speech are not typically characterized by higher levels of activity in these muscles; and when EMG levels during conversational speech are compared to maximal activation levels for these muscles (e.g., those observed during singing and the Valsalva maneuver), normally fluent adults show robust and sometimes near maximal recruitment during conversational speech. The adults who stutter had a lower operating range for these muscles during conversational speech, and their disfluencies did not produce relatively high activation levels. In summary, the present data require us to reject the claim that adults with a history of chronic stuttering routinely produce excessive levels of intrinsic laryngeal muscle activity. These results suggest that the use of botulinum toxin injections into the vocal folds to treat stuttering should be questioned.

Adult↗
PubMed1996

Immunologic, functional, and morphological characterization of three new human small intestinal epithelial cell lines.

BACKGROUND & AIMS: Epithelial cell cultures can be used for the study of epithelial cell biology, although human small intestinal cultures have not been available to date. The aim of this study was to characterize three cell lines derived from normal human duodenum. METHODS: Cells were cultured from tissue fragments obtained from endoscopic biopsy specimens and characterized with respect to morphology and cytokine gene expression and for the presence of vectorial transport. RESULTS: All cell lines grew as polarized continuous monolayers and were mostly cuboidal in shape but were not immortalized. Cells showed junctional complexes and sparse microvilli. All cell lines showed cytokeratins and mucin antigen but not chromagranin and messenger RNA for epidermal growth factor, interleukin 6, and vascular cell adhesion molecule 1. Disaccharidase activities were low and correlated with the low proportion of cells (1%-10%), showing positive immunocytochemistry for sucrase. Monolayer resistance varied from 30 to 200 ohms. One monolayer (BN) consistently showed secretion in response to forskolin (10 micromol/L), which could b inhibited by chloride-free buffer and apical addition of the chloride channel blocker diphenylamine decarboxylate. No monolayer had evidence of glucose transport. CONCLUSIONS: These three nonimmortalized lines show morphological, phenotypic, and transport characteristics of crypt-like intestinal epithelial cells. The pattern of messenger RNA expression suggests a growth-promoting and immunomodulatory role.

Aged↗
PubMed1996

Multiple cutaneous basal cell carcinomas: glutathione S-transferase (GSTM1, GSTT1) and cytochrome P450 (CYP2D6, CYP1A1) polymorphisms influence tumour numbers and accrual.

The genetic factors that mediate the pathogenesis of multiple primary cutaneous basal cell carcinomas (BCC) are largely unclear. Thus, some patients suffer many BCC (>30) and/or rapid accrual (number of tumours/year from first presentation) of further lesions. We have studied, in 827 English Caucasians, the influence of polymorphism in carcinogen-metabolizing enzymes on susceptibility to this cancer. Accordingly, we describe, first, a cross-sectional analysis of the influence of GSTM1, GSTT1, CYP2D6 and CYP1A1 genotypes on tumour numbers, and secondly, a longitudinal analysis, in 169 of these cases, of the effect of these genes on tumour accrual. We have confirmed the expected importance of age and number of lesions at presentation, and male gender and skin type as risk factors. Furthermore, the cross-sectional analysis showed CYP1A1 m1m1 (P = 0.004; rate ratio 1.242) and CYP2D6 EM (P < 0.001, rate ratio 1.266) are associated with increased numbers of BCC. The longitudinal study showed, after adjustment for age and tumour number at presentation, that GSTT1 null (P < 0.001, rate ratio 2.677) and CYP2D6 EM (P < 0.001, rate ratio 2.154) were significant determinants of accrual while CYP1A1 Ile/Ile was associated with slower accrual than the Ile/Val and Val/Val genotypes (P = 0.008, rate ratio 0.690). We believe these are the first genetic factors to be associated with tumour accrual. No significant interactions between genotypes were identified, though the combinations GSTM1 null/skin type 1 (P < 0.001, rate ratio 2.702), CYP2D6 EM/male gender (P = 0.049, rate ratio 1.279) and CYP2D6 EM/blue+green eyes (P = 0.046, rate ratio 1.388) influenced tumour numbers. Previous studies indicate the importance of effective repair of UV-damaged DNA in the pathogenesis of multiple BCC; indeed the influence of GSTM1 may result from its ability to utilize 5'-hydroxymethyluracil. However, the finding that CYP2D6 and CYP1A1 influence tumour numbers and accrual indicates detoxification of unknown molecules is important and supports the view that factors other than UV are important in the pathogenesis BCC.

Adult↗
PubMed1996

Helicobacter pylori and recurrent abdominal pain in children.

Recurrent abdominal pain is one of the most common presentations to pediatricians; yet an organic etiology can be found in only 10% of cases. Because infection with Helicobacter pylori in adults and children results in gastritis, a causative role for the organism has been postulated. To investigate this theory, we conducted a prospective case-control study in children with recurrent abdominal pain using serum H. pylori IgG antibodies measured by an enzyme immunoabsorbent assay. Age, sex, ethnicity, and socioeconomic status were adjusted in the statistical model. Five subjects (5.1%) and 14 controls (14.3%) had raised serum IgG antibodies to H. pylori (adjusted OR, 0.21; 95% confidence interval, 0.05, 0.85). The negative association between H. pylori and recurrent abdominal pain indicates that this organism is unlikely to have an important etiologic role in this disorder.

Abdominal Pain↗
PubMed1996

An Angelman syndrome clinic: report on 24 patients.

OBJECTIVE: Angelman syndrome (AS) is a rare congenital neurodevelopmental disorder with complex genetic aetiology. Diagnosis may be difficult and there is severe life-long disability. An AS clinic was commenced in Sydney, Australia, in 1993 with the aim of gathering information about the natural history of AS, management issues and parental concerns. METHODOLOGY: Patients were referred from metropolitan Sydney, rural New South Wales and interstate. A questionnaire, history, physical examination and diagnostic tests were undertaken. RESULTS: In the first year, 24 patients with AS were assessed. There were 11 males and 13 females, whose ages ranged from 3 to 30 years. The mean age of diagnosis was 12.8 years. The diagnosis was made by neurologists in four cases, by clinical geneticists in three cases, by paediatricians in two cases and 15 cases were diagnosed at the AS clinic. A clear history of epilepsy was obtained in 19 (79%) and in 15 of these patients the age of onset was during the first 4 years of life. An EEG had been performed in 21 patients, and in two the EEG was reported as normal. Fifteen of the patients (62.5%) could walk independently and in this cohort there was a significant sex difference in walking: 10/11 males compared to 5/13 females (P > 0.01). Five patients (21%) were in full-time permanent care. Genetic testing with appropriate DNA probes from chromosome 15 (q11-13), complete in 20 families, showed deletion in 12 patients (60%),uniparental disomy in 1(5%) and no detectable abnormality in 7 (35%). CONCLUSIONS: The diagnosis of AS should be considered in any patient with severe developmental disability particularly if there is a movement disorder and lack of speech. The control of epilepsy is a major management problem. Further research is needed to establish the frequency and type of seizures, the response to anticonvulsants and to determine if improvement can be expected with age. The mobility of patients should be assessed regularly, to determine the most appropriate options for intervention.

Adolescent↗
PubMed1996

The management of acute abdominal pain in children.

OBJECTIVE: Acute abdominal pain is a common problem in childhood, and appendicitis is frequently diagnosed by general practitioners and doctors working in emergency departments. The objective of the present report was to determine the frequency of appendicitis in a group of children with acute abdominal pain presenting to the emergency department of a general hospital, as well as attempting to analyse the manner in which these patients were managed. METHODOLOGY: The initial assessment in hospital (by resident hospital staff) of the study group of patients was analysed and their subsequent clinical progress documented. RESULTS: The present report shows that the vast majority of children with acute abdominal pain do not have appendicitis and that appendicitis is significantly over-diagnosed by junior hospital doctors. CONCLUSIONS: Appendicitis is a clinical diagnosis, best made by an experienced member of the paediatric surgical team. Frequent review, with a minimum of investigations, provides the best means of making a rational decision regarding surgery.

Abdomen, Acute↗
PubMed1996

Clinical features in 27 patients with Angelman syndrome resulting from DNA deletion.

We report the clinical features in 27 Australasian patients with Angelman syndrome (AS), all with a DNA deletion involving chromosome 15(q11-13), spanning markers from D15S9 to D15S12, about 3 center dot 5 Mb of DNA. There were nine males and 18 females. All cases were sporadic. The mean age at last review (end of 1994) was 11 center dot 2 years (range 3 to 34 years). All patients were ataxic, severely retarded, and lacking recognisable speech. In all patients, head circumference (HC) at birth was normal but skewed in distribution, with 62 center dot 5% at the 10th centile. At last review HC was around the 50th centile in three patients (12 center dot 5%) while 15 had poor postnatal head growth. Short stature was not invariable, 5/26 (19%) were on or above the 50th centile. Hypotonia at birth was recorded in 15/24 (63%) and neonatal feeding difficulties were recorded in 20/26 (77%). Epilepsy was present in 26/27 (96%) with onset by the third year of life in 20 patients (83%). Improvement in epilepsy was reported in 11/16 patients (69%) with age. An abnormal EEG was reported in 25/25 patients. Hypopigmentation was present in 19/26 (73%). One patient had oculocutaneous albinism. Five patients could not walk independently. Of the remaining 22 who could walk, age of onset of walking ranged from 2 to 8 years. Disrupted sleep patterns were present in 18/21 patients (86%), with improvement in 9/12 patients (75%) over 10 years of age. The clinical features in this group of deletional AS patients were similar to previous reports, but these have not separated patients into subgroups based on DNA studies. In our group of deletional cases, 100% showed severe mental retardation, ataxic movements, absent language, abnormal EEG, happy disposition (noted in infancy in 95%), normal birth weight and head circumference at birth, and a large, wide mouth. These features occurred with a higher frequency than in AS patients as a whole. Our study also provided information on the evolution of the phenotype. The data can act as a benchmark for comparisons of AS resulting from other genetic mechanisms.

Adolescent↗
PubMed1996

A 3 1/2 year old girl with distal trisomy 19q defined by FISH.

A 3 1/2 year old girl was evaluated because of developmental delay. Short stature was evident with height between the 3rd and 10th centiles, while weight and head circumference were on the 50th centile. Dysmorphic features consisted of a high bossed forehead, pointed short ear lobes, small nose, bilateral convergent strabismus, left simian crease, a gap between the first and second toes bilaterally, mild clinodactyly, and a broad, barrel shaped thorax. Cytogenetic investigations showed an unbalanced karyotype, 46,XX,10q+, which was de novo in origin. Fluorescence in situ hybridisation (FISH) using three library probes (from chromosomes 10, 19, and 19q) and a YAC probe (from 10q telomere) showed that the additional material on 10q was derived from chromosome 19q. The patient had an unbalanced translocation, 46,XX,-10,+der(10)t(10;19)(q26.3; q13.3), which resulted in distal trisomy 19q. Few other cases of proven distal trisomy 19q are available for comparison of clinical features.

Child↗