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Biomedical subjects

A L Collins

Publications and source records attributed to A L Collins.

At least 19 recordsLinked to original sources
PubMed2006

Duplications of proximal 16q flanked by heterochromatin are not euchromatic variants and show no evidence of heterochromatic position effect.

Extra euchromatic material was found within the major heterochromatic block of chromosome 16 (16qh) in one de novo case and seven members of two families. In contrast to the euchromatic variants of chromosome 9 (9qh), which are derived from pericentromeric euchromatin, molecular cytogenetics confirmed that these duplications were of 16q11.2-->q12.2 in the de novo case, of 16q11.2-->q13 in three members of family 1 and 16q11.2-->q12.1 in four members of family 2. The duplication had arisen as a post-zygotic mitotic event in the mother of family 1 and been transmitted paternally in family 2. An insertional mechanism of origin is proposed for the duplications in case 1 and family 1. Expression at the 16q13 matrix metalloproteinase-2 (MMP2)locus in families 1 and 2 was proportional to genomic copy number and not therefore consistent with position effect silencing due to the flanking blocks of heterochromatin. We conclude that proximal 16q duplications within 16qh are not novel euchromatic variants but associated with a variable phenotype including developmental delay, speech delay, learning difficulties and behavioural problems. The behavioural problems in families ascertained through affected children are much less severe than those encountered in previous patients ascertained as adults.

Adolescent↗
PubMed2004

Within- and between-laboratory precision in the measurement of body volume using air displacement plethysmography and its effect on body composition assessment.

OBJECTIVE: To determine and compare the extent of within- and between-laboratory precision in body volume (BV) measurements using air displacement plethysmography (ADP), the BOD POD body composition system, and to interpret any such variability in terms of body composition estimates. DESIGN: Repeated test procedures of BV assessment using the BOD POD ADP were reproduced at two laboratories for the estimation of precision, both within and between laboratories. SUBJECTS: In total, 30 healthy adult volunteers, 14 men (age, 19-48 y; body mass index (BMI), 19.7-30.3 kg/m2) and 16 women (age, 19-40 y; BMI, 16.3-35.7 kg/m2), were each subjected to two test procedures at both laboratories. Two additional volunteers were independently subjected to 10 repeated test procedures at both laboratories. MEASUREMENTS: Repeated measurements of BV, uncorrected for the effects of isothermal air in the lungs and the surface area artifact, were obtained using the BOD POD ADP, with the identical protocol being faithfully applied at both laboratories. Uncorrected BV measurements were adjusted to give estimates of actual BV that were used to calculate body density (body weight (BWt)/actual BV) from which estimates of body composition were derived. The differences between repeated BV measurements or body composition estimates were used to assess within-laboratory precision (repeatability), as standard deviation (SD) and coefficient of variation; the differences between measurements reproduced at each laboratory were used to determine between-laboratory precision (reproducibility), as bias and 95% limits of agreement (from SD of the differences between laboratories). RESULTS: The extent of within-laboratory methodological precision for BV (uncorrected and actual) was variable according to subject, sample group and laboratory conditions (range of SD, 0.04-0.13 l), and was mostly due to within-individual biological variability (typically 78-99%) rather than to technical imprecision. There was a significant (P<0.05) bias between laboratories for the 10 repeats on the two independent subjects (up to 0.29 l). Although no significant bias (P=0.077) was evident for the sample group of 30 volunteers (-0.05 l), the 95% limits of agreement were considerable (-0.68 to 0.58 l). The effects of this variability in BV on body composition were relatively greater: for example, within-laboratory precision (SD) for body fat as % BWt was between 0.56 and 1.34% depending on the subject and laboratory; the bias (-0.59%) was not significant between laboratories, but there were large 95% limits of agreement (-3.67 to 2.50%). CONCLUSION: Within-laboratory precision for each BOD POD instrument was reasonably good, but was variable according to the prevailing conditions. Although the bias between the two instruments was not significant for the BV measurements, implying that they can be used interchangeably for groups of similar subjects, the relatively large 95% limits of agreement indicate that greater consideration may be needed for assessing individuals with different ADP instruments. Therefore, use of a single ADP instrument is apparently preferable when assessing individuals on a longitudinal basis.

Adult↗
PubMed2003

Evaluation of factors determining the precision of body composition measurements by air displacement plethysmography.

OBJECTIVES: To investigate methodological precision of air displacement plethysmography for assessment of body composition in a heterogenous sample of adults. DESIGN: Accuracy of volume measurements by air displacement plethysmography (ADP) for a range of known volumes was ascertained. Repeated measurements of body volume, lung volume, and derived body composition using the BODPOD measurement system were performed. Influence of surface area estimation on ADP measurement was investigated as a possible source of variation. SETTING: Clinical Nutrition Laboratory, School of Health & Sports Science, University of North London, London, UK. SUBJECTS: One hundred and two healthy subjects (57 women, 45 men) who ranged in age between 16 and 55 y and in BMI (kg/m(2)) between 17.8 and 41.9. STUDY DESIGN: Cross-sectional study of healthy adults for comparison with previous studies. Repeat measurements of raw body volume, lung volume and % body fat (BF) by ADP were all performed on the same day. RESULTS: From the range of known volumes a marked increase in the CV and a significantly greater measurement error were found at volumes below 40 l (P=0.04). Repeat measurements of raw body volume in human subjects resulted in a technical error equivalent to 0.8% BF. There was no significant difference found between measured and predicted lung volume and the 95% confidence interval for difference was only 0.3% BF. Repeat measurements of lung volume in our subset resulted in a technical error equivalent to 0.5% BF. Although body surface area estimation only accounted for variation in % BF of 0.1%, the extent of variation appeared to be governed by leanness (P<0.001). CONCLUSIONS: Although ADP retains excellent precision, in practice, repeat measurements of ADP should be performed whenever possible to allow for erroneous volume measurement within one procedure. Protocols for ADP measurement should be created with an awareness of those factors, which may affect measurements. SPONSORSHIPS: This study was supported by the University of North London Diversity & Development Fund.

Adolescent↗
PubMed2001

Construct validity of Wechsler factor scores.

The construct validity of the Verbal Comprehension. Perceptual Organization, and Freedom from Distractibility factor scores was examined in a sample of school-aged referred children. Examination of correlations between factor scores and neuropsychological and achievement tests generally supported the construct validity of the factors. The Verbal Comprehension factor was associated with verbal, quantitative, and concept-formation abilities. The Perceptual Organization factor was related to nonverbal concept formation, tactual performance, and visual attention. The Freedom from Distractibility factor demonstrated a complex pattern of correlations and appeared to reflect a range of abilities including quantitative, language, attentional, and concept formation.

Adolescent↗
PubMed1998

An evaluation of the Weber classification of ankle fractures.

This retrospective study over a 3 year follow-up was designed to establish the significance of the Weber classification of ankle fractures with regards to functional and radiographic outcome. One hundred and seven patients were available for follow-up, of which 88 ankles could be classified with the Weber system. Medial malleolar fractures alone and pilon fractures could not be classified with this system. A correlation was found between the type of Weber fracture and the overall ankle score. This held true for unimalleolar fractures alone. More complex bimalleolar and trimalleolar fractures did not follow this convention. Logistical regression analysis was used to evaluate other predictors of outcome. Bimalleolar and trimalleolar fractures were statistically significant predictors of a poorer outcome (P = 0.033, P = 0.021). The initial degree of displacement was also determined to be a predictor of outcome (P = 0.0133) as was the operative reduction (P = 0.0113). Using linear regression, older age (> 62 years) was also established as a predictor of a poorer outcome (P < 0.05). The Weber classification was found to be a predictor of outcome in unimalleloar ankle fractures and not for multimalleolar fractures. We have identified further predictors of a poorer outcome in ankle fractures as the degree of initial injury, the number of malleoli fractured and older age. These factors were found to have greater significance in predicting outcome than the level of fibular fracture alone. We have identified a deficiency of the Weber system in excluding these criteria and have addressed this by modifying the existing system to include the number of malleoli involved, thus providing a more useful prognostic tool.

Adolescent↗
PubMed1997

Multiskilling: a survey of occupational therapy practitioners' attitudes.

OBJECTIVE: Multiskilling has been identified as one means of reducing she cost of health care. This study examined occupational therapy practitioners' knowledge of multiskilling, how it is affecting service delivery and quality of care, and how therapists believe the addition of skills should occur. METHOD: A questionnaire was constructed for the survey and mailed to a random sample of 200 occupational therapists and occupational therapy assistants, all of whom were members of the American Occupational Therapy Association. RESULTS: The 117 respondents had a moderate understanding of multiskilling. They responded that multiskilling is beneficial to both the occupational therapy profession and the clients it serves, but they were also aware of its potential risks or disadvantages. According to respondents, multiskilling occurs formally through defined protocol and; more commonly, informally, driven by necessity and the desire to treat the client most effectively. CONCLUSION: The results indicate a need for the occupational therapy profession to define multiskilling and cross training; develop ways of serving clients that respond to administrative needs and constraints while preserving the uniqueness of occupational therapy; and monitor treatment outcomes of all service delivery methods to provide information regarding efficiency, effectiveness, and client satisfaction.

Adult↗
PubMed1995

Crossover analysis in a British family suggests that Coffin-Lowry syndrome maps to a 3.4-cM interval in Xp22.

Coffin-Lowry syndrome (CLS; MIM 303600) in an uncommon X-linked disorder causing mental retardation and skeletal abnormalities. Most recently it was mapped to a 5.6-centimorgan (cM) region of Xp22, flanked distally by AFM291wf5 and proximally by DXS1052 [Biancalana et al., 1994: Genomics 22:617-625]. We present information which supports this localization and further narrows the region to approximately 3.4 cM. A recombination in a carrier from a British family mean that DXS365 is the closest proximal flanking marker identified to date for the region thought to contain the CLS gene. This information reduces the region of interest by approximately 2.2 cM, a significant decrease in terms of the scale of effort which will be required to isolate and analyze candidate genes.

Adolescent↗
PubMed1995

Fluorescence in situ hybridisation studies provide evidence for somatic mosaicism in de novo dystrophin gene deletions.

The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect somatic mosaicism in mothers of isolated deletion cases of Duchenne/Becker muscular dystrophy. A control female with known germline and somatic mosaicism was examined, and both the normal cell line and the carrier cell line were detected. Subsequent FISH analysis of three other mothers of boys with apparent de novo dystrophin gene deletions revealed a second patient with a high level of somatic mosaicism, suggesting that a proportion of de novo dystrophin gene deletions occur as mitotic errors early in development rather than as meiotic errors during gametogenesis.

Cells, Cultured↗
PubMed1995

A mother and three daughters with congenital dislocation of the hip and a characteristic facial appearance: a new syndrome?

We describe a mother and her three daughters who all have bilateral congenital dislocation of the hip. The mother has had no other medical problems and is on the 90th centile for height. Her three daughters resemble each other strongly with facial characteristics which include hypertelorism, epicanthic folds, puffiness around the eyes, a flat mid-face and a carp-shaped mouth. All three daughters are on the 3rd centile for height, with their head circumference on a higher centile and all had an ASD. Other features include congenital dislocation of one knee (one), congenital inguinal hernia (one) and vesico-ureteric reflux (one). They also have clinodactyly and hyperextensible finger joints, both features also seen in their father, whose height is on the 3rd centile and who had bilateral congenital inguinal herniae. Collagen studies of skin and ligament were normal. This family does not appear to fit with any of the recognized congenital dislocation syndromes and we suggest that they may represent a previously undescribed syndrome.

Adult↗
PubMed1994

Linkage of a human brain malformation, familial holoprosencephaly, to chromosome 7 and evidence for genetic heterogeneity.

Holoprosencephaly (HPE) is a common malformation of the developing forebrain and midface characterized by incomplete penetrance and variable expressivity. Familial HPE has been reported in many families with autosomal dominant inheritance in some and apparent autosomal recessive inheritance in others. We have examined 125 individuals from nine families with autosomal dominant HPE. Expression in gene carriers varied from alobar HPE and cyclopia through microforms such as microcephaly or single central incisor to normal phenotype. We performed linkage studies by either Southern blot or polymerase chain reaction analyses with DNA markers (D7S22, D7S550, and D7S483) that are deleted from some patients with sporadic HPE and flank a translocation breakpoint in 7q36 associated with HPE. The strongest support for linkage was with D7S22, which was linked with no recombination to autosomal dominant HPE in eight of nine families with a combined logarithm of odds score of 6.4 with an affected-only model-free analysis and 8.2 with a reduced-penetrance model and all phenotypes. Close linkage to this region could be excluded in one family, and there was significant evidence of genetic heterogeneity. These results show that a gene for autosomal dominant HPE is located in a chromosomal region (7q36) known to be involved in sporadic HPE with visible cytogenetic deletions. They also demonstrate genetic heterogeneity in familial HPE. We hypothesize that mutations of a gene in 7q36, designated HPE3, are responsible for both sporadic HPE and a majority of families with autosomal dominant HPE.

Adolescent↗
PubMed1994

Germline and somatic mosaicism in a female carrier of Duchenne muscular dystrophy.

The family of a male with Duchenne muscular dystrophy (DMD) and a deletion within the dystrophin gene has been studied. Polymerase chain reaction analysis of ectopic mRNA from peripheral blood T+B lymphocytes and the use of (CA)n repeat polymorphisms in and around the deleted region showed the proband's mother to be both a germline mosaic and a somatic mosaic for the deletion seen in her son. The mutation therefore occurred as a mitotic event early in embryogenesis.

Child, Preschool↗
PubMed1994

A comparison of the clinical and cytogenetic findings in nine patients with a ring (X) cell line and 16 45,X patients.

In this study, the clinical, IQ, and cytogenetic findings in nine Turner's syndrome patients with a ring (X) cell line are compared with those in 16 patients in whom only a 45,X cell line could be found. The ring (X) patients lacked many of the "classic" Turner's syndrome features and the majority were not karyotyped until after the age of 11, usually because of pubertal failure. They also showed a reduction in IQ of 11 points compared with the 45,X group. Some ring (X) patients show characteristic facial features including a broad nose with anteverted nostrils, prominent philtrum, long palpebral fissures, and a wide mouth with a thin upper lip. Neither the physical features nor the IQ are related to the parental origin of the chromosome error. In the majority of cases the ring (X) chromosome was late replicating but XIST activity is being studied further.

Adolescent↗
PubMed1994

Further observations on the Floating-Harbor syndrome.

We report two unrelated female patients aged 2- and 15-years-old with short stature, language delay and craniofacial anomalies consistent with the Floating-Harbor syndrome. One patient had evidence of coeliac disease. This increasingly recognized association suggests pleiotropism.

Abnormalities, Multiple↗
PubMed1993

Holoprosencephaly: a family showing dominant inheritance and variable expression.

A family with probable dominant holoprosencephaly is presented with five affected subjects in two sibships, the offspring of healthy sisters who are presumed gene carriers. Of the affected children, three had cebocephaly and died shortly after birth. One had left choanal atresia, retinal coloboma, a single central maxillary incisor, microcephaly, short stature, and learning problems. Another had only a single central maxillary incisor. The occurrence of hypotelorism, microcephaly, and unilateral cleft lip and palate as minor manifestations of the gene in possible and probable gene carriers is discussed.

Abnormalities, Multiple↗
PubMed1993

Three patients with ring (X) chromosomes and a severe phenotype.

Three patients with mosaicism and a cell line containing a small ring (X) chromosome are described. Their phenotype is similar to several previously reported patients with a 45,X/46,X,r(X) karyotype and a phenotype far more severely affected than expected in Turner's syndrome. The clinical picture includes mental retardation, a facial appearance reminiscent of the Kabuki make up syndrome, and limb anomalies. Some of the patients also had streaky hyperpigmentation of the skin in a pattern suggesting dermal mosaicism. It has been hypothesised that the severe phenotype might be the result of the small r(X) chromosome remaining active. However, there is little critical evidence to support this suggestion, while there is considerable evidence against it, including (1) a similar phenotype in 45,X/46,X,r(Y) patients, (2) the late replication of some of the small r(X) chromosomes associated with this phenotype, and (3) the expression of XIST in some of the affected patients.

Dosage Compensation, Genetic↗