Bias resulting from missing information: some epidemiological findings.

The biases resulting from missing information were examined in three psychiatric epidemiological studies. In each study, cases with missing information could be compared with the main sample because data were available from several sources or at several points in time through a longitudinal study. In almost all instances, cases with missing data differed systematically in terms of variables crucial to the questions being studied. In general, they tended to include a higher proportion with problems of various kinds--such as, behavioural deviance, reading backwardness, child or adult psychiatric disorder, and marital discord. The characteristics or circumstances of those giving information were generally more strongly associated with co-operation in testing or interviewing than the characteristics of those about whom information was sought. In some situations, the nature and degree of distortion resulting from missing information could lead to biased results.     

Synergism between Trichuris suis and the microbial flora of the large intestine causing dysentery in pigs.

The role of the microbial flora of the large intestine in experimental Trichuris suis infection was studied by comparing the clinical syndrome in conventionally reared (CR) pigs, specific pathogen-free pigs, and gnotobiotic pigs. Thedisease in CR pigs was characterized by a severe mucohemorrhagic enteritis; in contrast, a mild catarrhal enteritis was observed in specific pathogen-free and gnotobiotic pigs.Spirochaetes and vibrio-like organisms were observed only in CR pigs and increased during the clinical phase of the disease. The clinical syndrome was not transmitted by oral administration of intestinal or fecal material from infected CR pigs to CR pigs free of T. suis. Smaller numbers of T. suis produced diarrhea in CR pigs and significantly reduced the growth rates of infected animals; clinical signs and the reduction in growth rate was prevented by incorporating an antibacterial substance (dimetridazole) in the food. Although clinical trichuriasis closely resembles swin dysentery, the two syndromes seem to be distinct. The present results suggest that a microbial component acts synergistically with T. suis to produce the severe clinical syndrome in CR pigs, but identification of the microbial component and the mechanism by which clinical signs are produced await further studies of the bacterial flora of the large intestine of pigs.     

A comparative study of infantile autism and specific developmental receptive language disorders III. Discriminant function analysis

A psychometric, observational, and interview study was undertaken with 47 boys, aged 4 1/2 to 10 years, with nonverbal IQs of 70+ and a severe developmental disorder of language comprehension. Separate discriminant function analyses, based on behavioral, language, or cognitive features, showed little overlap between clinically defined autistic and dysphasic subgroups. Moreover, the discrimination could be made as clearly on language or cognitive characteristics as on social or behavioral criteria. Language abnormalities and behavioral features also intercorrelated within the autistic subgroup. It is concluded that autism and dysphasia differ in important ways and that a cognitive deficit is an essential part of the syndrome of autism.This study was supported in part by grants from the Department of Education and Science and the Bethlem-Maudsley Hospital Research Fund. We are very grateful to the Directors and staff of the Units from which cases were selected for their ready cooperation in allowing us to examine children in each Unit. All went out of their way to provide help throughout the investigation. We are especially grateful to the parents of the children for their forbearance in allowing us to interview them at considerable length and for their exceptional kindness to individual investigators. We are also very grateful to Mr. B. S. Everitt of the Biometrics Department, Institute of Psychiatry, for statistical advice.     

Chromosomal assignments of human genes for serine proteases trypsin,chymotrypsin B,and elastase

The genes for the serine proteases trypsin, chymotrypsin B, and elastase were chromosomally assigned in man using cDNA probes that have been isolated from a rat pancreatic cDNA library. DNA from human × rodent somatic cell hybrids was cleaved with BamHI or EcoRI and analyzed by Southern filter hybridization methods for the segregation of the genes for trypsin-1 (TRY1), chymotrypsin B (CTRB), and elastase-1 (ELA1). TRY1 was assigned to human chromosome 7q22qter, CTRB to chromosome 16, and ELA1 to chromosome 12. Although the three genes are members of the same gene family, they are dispersed over different chromosomes.Preliminary chromosome assignments of chymotrypsin B (1) and of trypsin and elastase (2) have been made in abstract.     

Use of three-dimensional animation for regional anaesthesia teaching: application to interscalene brachial plexus blockade

Background. Using commercial computer graphics software (TrueSpace),we constructed a virtual-reality model for teaching interscalenebrachial plexus block. This tool combines the clarity of schematicdrawings and the clinical relevance of video clips and livedemonstrations. The aim is to accelerate learning and aid retentionof relevant information. Method. We made a series of continuous short virtual-realityanimations demonstrating the steps to perform an interscaleneblock. Superficial structures were made transparent to showthe anatomical relevance of landmarking and needle manipulation.The clips were presented to delegates at a training course inOxford. Delegates were surveyed to ascertain whether or notthe presentation enhanced their understanding of anatomy andregional block technique. Before and after the presentation,delegates indicated surface landmarking, needle angulation,and movement on photographs of the lateral and anterolateralneck views of two volunteers. The markings were analysed bytwo independent assessors and rated as ‘good’, ‘bad’,or ‘ungradeable’. The percentage improvement foreach skill group was calculated and McNemar's test applied. Results. Of 24 respondents, the majority thought that the presentationenhanced their understanding of the anatomical (87.5%) and technicalprinciples (79.2%) of interscalene blocks. Analysis of the markedphotographs showed an overall 24.1% improvement in landmarkingskills after the teaching presentation (P<0.001). Changeswere significant in moderately experienced skill groups (P<0.001)but not for the very experienced (P>0.5) and the inexperiencedskill groups (P<0.1). There was 76.3% concordance in scoringbetween the two assessors. Conclusion. Three-dimensional animation is a promising new toolto accelerate the learning of regional anaesthetic techniques. This paper has been presented at the 13th World Congress ofAnaesthesiologists, Paris, April 2004. The abstract is publishedin the accompanying CD-ROM under reference S028. This paperhas also been presented at the Society of Computing and Technologyin Anaesthesia Winter Meeting, Manchester, November 2003 andat the National Anaesthetic Research Meeting, Penrith, June2004.     

Elektronenmikroskopische Untersuchung der Haut bei Angiokeratoma corporis diffusum

Summary Electron microscopic findings in the skin in two cases of angiokeratoma corporis diffusum (males 41 and 38 years of age resp.) are presented. In one of these cases only formol fixed autopsy material was available; in the other case in respect of electron microscopy adequately fixed biopsy material was used. In the formol fixed autopsy material, more especially in endothelial cells and fibrocytes, chiefly osmiophilic granules were observed, which were indicated as type 1 and 2. In the adequately fixed biopsy material of the second patient mainly osmiophilic granules of a lamellar type (type 3) were seen. The latter consisted of lamellar systems with tightly concentrically arranged alternating dense and light lines. The thickness of the osmiophilic lines was 26 Å, of the osmiophobic ones 36 Å, which means a periodicity of 62 Å. The lamellar system often enclosed a granular or homogenous electron-opaque centre. They showed a close resemblance to lamellar osmiophilic granules demonstrated in Tay-Sachs disease, but differed from those by a number of ultra-structural details. The question, whether type 3 osmiophilic bodies can be considered as specific for angiokeratoma corporis diffusum is discussed. In addition attention is drawn to the marked predominence of osmiophilic granules of the types 1 and 2 in the formol fixed autopsy material. Unfavourable conditions (unsuitable formol fixation, autolysis) may have been partly responsible for this phenomenon.Zusammenfassung In zwei. Fällen von Angiokeratoma corporis diffusum wurde die Haut elektronenmikroskopisch untersucht. Im einen Falle stand mit Formol fixiertes Material (Sektion) zur Verfügung; im zweiten Falle konnte adäquat fixiertes Biopsiematerial zur elektronenmikroskopischen Untersuchung benutzt werden. In dem mit Formol fixierten einer Obduktion entnommenen Material wurden in Endothelzellen und Fibrocyten hauptsächlich osmiophile Körperchen gefunden, die als Typ 1 und 2 beschrieben wurden. In dem für Elektronenmikroskopie adäquat fixierten Biopsiematerial überwogen dagegen aus parallellisierten Lamellen aufgebaute osmiophile Körperchen (Typ 3), welche oft ein schwach elektronendichtes homogenes bzw. feinkörniges Zentrum umschlossen (Typ 3). Die osmiophilen Lamellen zeigten hier eine Dicke von 26 Å, die osmiophobe eine Dicke von 36 Å, was eine Periodizität von 62 Å bedeutet. Die Möglichkeit, daß die osmiophilen Lamellenkörperchen (Typ 3) als charakteristisch für Angiokeratoma corporis diffusum zu betrachten sind, wurde erwogen. Das Vorwiegen von osmiophilen Körperchen vom Typ 1 und 2 beim formolfixierten autoptischen Material läßt vermuten, daß hier die weniger günstigen Verhältnisse (Fixierung in nichtisotonischem, nichtgepuffertem Formol, Autolyse!) zu dem in den Vordergrund treten dieser Type beigetragen haben.     

Altered laryngeal sensation: a potential cause of apnea of infancy

Delayed maturation of respiratory control of breathing and the laryngeal adductor reflex (LAR) are commonly implicated in infant apnea. A swallow response occurs to remove the stimulus from the pharynx to prevent aspiration once the glottis reopens. Induction of apnea by poorly cleared endogenous upper airway secretions has been postulated to be a potential cause of infant apnea. Our purpose was to determine whether alteration in the LAR, an indicator of laryngeal sensation, and the presence of secretions influenced the responsiveness of the LAR in infants with apnea. The LAR was induced in 20 infants with apnea (median gestational age, 36.5 weeks) by application of air pulses of controlled duration (50 ms) and intensity (2.5 to 10 mm Hg) to the aryepiglottic fold. Twenty infants evaluated for upper respiratory tract anomalies were used as a comparison group (median gestational age, 39 weeks). The infants with apnea required higher-intensity stimuli (p < .001) to induce the LAR (6.2 +/- 1.6 mm Hg) than did the comparison group (4.3 +/- 1.0 mm Hg) and demonstrated poorer clearance of secretions (p < .001). These findings were significant even when we adjusted for postconceptional age at the time of the test (p = .007). The findings of this study suggest that decreased laryngeal sensitivity results in poor endogenous secretion clearance and that it may induce a prolonged glottic closure event to prevent aspiration. This closure may play a role in infant apnea.     

Developmental language disorders--a follow-up in later adult life. Cognitive, language and psychosocial outcomes

BACKGROUND: Little is known on the adult outcome and longitudinal trajectory of childhood developmental language disorders (DLD) and on the prognostic predictors. METHOD: Seventeen men with a severe receptive DLD in childhood, reassessed in middle childhood and early adult life, were studied again in their mid-thirties with tests of intelligence (IQ), language, literacy, theory of mind and memory together with assessments of psychosocial outcome. They were compared with the non language disordered siblings of the DLD cohort to control for shared family background, adults matched to the DLD cohort on age and performance IQ (IQM group) and a cohort from the National Child Development Study (NCDS) matched to the DLD cohort on childhood IQ and social class. RESULTS: The DLD men had normal intelligence with higher performance IQ than verbal IQ, a severe and persisting language disorder, severe literacy impairments and significant deficits in theory of mind and phonological processing. Within the DLD cohort higher childhood intelligence and language were associated with superior cognitive and language ability at final adult outcome. In their mid-thirties, the DLD cohort had significantly worse social adaptation (with prolonged unemployment and a paucity of close friendships and love relationships) compared with both their siblings and NCDS controls. Self-reports showed a higher rate of schizotypal features but not affective disorder. Four DLD adults had serious mental health problems (two had developed schizophrenia). CONCLUSION: A receptive developmental language disorder involves significant deficits in theory of mind, verbal short-term memory and phonological processing, together with substantial social adaptation difficulties and increased risk of psychiatric disorder in adult life. The theoretical and clinical implications of the findings are discussed.