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Biomedical subjects

K Davies

Publications and source records attributed to K Davies.

At least 19 recordsLinked to original sources

Cosegregation of a novel homozygous CYP11B1 mutation with the phenotype of non-classical congenital adrenal hyperplasia in a consanguineous family.

We report a novel missense mutation of CYP11B1 causing non-classical 11beta-hydroxylase deficiency in 3 members of a consanguineous Turkish family. Two siblings presented with clinical evidence of precocious pseudopubarche. Biochemistry suggested 11beta-hydroxylase deficiency and genetic analysis revealed that they were homozygous for the missense mutation L489S within exon 9 of the CYP11B1 gene. The unaffected parents were heterozygotes for the same mutation. In addition, a paternal aunt of the affected siblings presenting with primary infertility and mild hirsutism was found to have the same homozygous mutation. This is the first report of a homozygous mutation in non-classical congenital adrenal hyperplasia that cosegregates with clinical phenotype. The significance of the missense mutation L489S in CYP11B1 is further supported by the conservation of leucine at position 489 in CYP11 genes in eleven other species. Molecular modelling of the enzyme suggests that the mutation L489S in CYP11B1 may alter the enzyme's substrate-binding affinity. These findings suggest that this homozygous mutation affects 11beta-hydroxylase function, resulting in the clinical features of non-classical adrenal hyperplasia in this family.

Adrenal Hyperplasia, Congenital↗

Joint hypermobility syndrome in childhood. A not so benign multisystem disorder?

OBJECTIVES: Joint hypermobility (JH) or "ligamentous laxity" is felt to be an underlying risk factor for many types of musculoskeletal presentation in paediatrics, and joint hypermobility syndrome (JHS) describes such disorders where symptoms become chronic, often more generalized and associated with functional impairment. Clinical features are felt to have much in common with more severe disorders, including Ehlers-Danlos syndrome (EDS), osteogenesis imperfecta and Marfan syndrome, although this has not been formally studied in children. We defined the clinical characteristics of all patients with joint hypermobility-related presentations seen from 1999 to 2002 in a tertiary referral paediatric rheumatology unit. METHODS: Patients were identified and recruited from paediatric rheumatology clinic and ward, and a dedicated paediatric rheumatology hypermobility clinic at Great Ormond Street Hospital. Data were collected retrospectively on the patients from the paediatric rheumatology clinics (1999-2002) and prospectively on patients seen in the hypermobility clinic (2000-2002). Specifically, historical details of developmental milestones, musculoskeletal or soft tissue diagnoses and symptoms, and significant past medical history were recorded. Examination features sought included measurements of joint and soft tissue laxity, and associated conditions such as scoliosis, dysmorphic features, cardiac murmurs and eye problems. RESULTS: One hundred and twenty-five children (64 females) were included on whom sufficient clinical data could be identified and who had clinical problems ascribed to JH present for longer than 3 months. Sixty-four were from the paediatric rheumatology clinic and 61 from the hypermobility clinic. No differences were found in any of the measures between the two populations and results are presented in a combined fashion. Three-quarters of referrals came from paediatricians and general practitioners but in only 10% was hypermobility recognized as a possible cause of joint complaint. The average age at onset of symptoms was 6.2 yr and age at diagnosis 9.0 yr, indicating a 2- to 3-yr delay in diagnosis. The major presenting complaint was arthralgia in 74%, abnormal gait in 10%, apparent joint deformity in 10% and back pain in 6%. Mean age at first walking was 15.0 months; 48% were considered "clumsy" and 36% as having poor coordination in early childhood. Twelve per cent had "clicky" hips at birth and 4% actual congenital dislocatable hip. Urinary tract infections were present in 13 and 6% of the female and male cases, respectively. Thirteen and 14%, respectively, had speech and learning difficulties diagnosed. A history of recurrent joint sprains was seen in 20% and actual subluxation/dislocation of joints in 10%. Forty per cent had experienced problems with handwriting tasks, 48% had major limitations of school-based physical education activities, 67% other physical activities and 41% had missed significant periods of schooling because of symptoms. Forty-three per cent described a history of easy bruising. Examination revealed that 94% scored > or =4/9 on the Beighton scale for generalized hypermobility, with knees (92%), elbows (87%), wrists (82%), hand metacarpophalangeal joints (79%), and ankles (75%) being most frequently involved. CONCLUSIONS: JHS is poorly recognized in children with a long delay in the time to diagnosis. Although there is a referral bias towards joint symptoms, a surprisingly large proportion is associated with significant neuromuscular and motor development problems. Our patients with JHS also show many overlap features with genetic disorders such as EDS and Marfan syndrome. The delay in diagnosis results in poor control of pain and disruption of normal home life, schooling and physical activities. Knowledge of the diagnosis and simple interventions are likely to be highly effective in reducing the morbidity and cost to the health and social services.

Adolescent↗

Final adult height and body mass index after cure of paediatric Cushing's disease.

OBJECTIVE: Linear growth data after cure of paediatric Cushing's disease (CD) have been reported infrequently. We evaluated final adult height (FH) and body mass index (BMI) in a cohort of paediatric patients treated successfully for CD. PATIENTS AND METHODS: Fourteen patients (10 male, age range 6.4-16.6 years) fulfilled the diagnostic criteria for CD. All had had transsphenoidal surgery (TSS), combined with pituitary irradiation (RT) (45 Gy in 25 fractions) in six. All were cured (post-TSS cortisol < 50 nmol/l or mean cortisol post-RT < 150 nmol/l). Subjects analysed had bone ages at diagnosis of < 15 'years' (male) and < 13 'years' (female). RESULTS: At diagnosis, height SDS was [mean (range)]-2.5 (-4.2 to -0.8) and body mass index (BMI) SDS +2.7 (0.8-5.1). Following cure, 13 patients had GH deficiency (peak GH < 20 mU/l) and were treated with hGH (+ GnRH analogue in four). Height SDS at FH (n = 10) or latest assessment (n = 4) was -1.3 (-3.9-0.2) and increased compared to diagnosis (P < 0.01). The difference between final or latest height SDS and target height SDS was -1.2 (-3.3-0.5), that is less (P < 0.01) than the difference between the height SDS at diagnosis and target height SDS of -2.4 (-3.9 to -0.5). At final height or latest assessment, BMI SDS was +1.7 (0.4-6.2), being decreased compared to diagnosis (P < 0.05) but greater than the normal population (P < 0.01). CONCLUSION: Catch-up growth was demonstrated in paediatric patients cured from CD, with the majority achieving FH within target height range. Early diagnosis and treatment of GH deficiency is recommended to achieve optimal long-term growth. Excess adiposity remains a potential long-term complication.

Adolescent↗

Blockade of platelet-derived growth factor receptor-beta by CDP860, a humanized, PEGylated di-Fab', leads to fluid accumulation and is associated with increased tumor vascularized volume.

PURPOSE: CDP860 is an engineered Fab' fragment-polyethylene glycol conjugate, which binds to and blocks the activity of the beta-subunit of the platelet-derived growth factor receptor (PDGFR-beta). Studies in animals have suggested that PDGFR-beta inhibition reduces tumor interstitial fluid pressure, and thus increases the uptake of concomitantly administered drugs. The purpose of this study was to determine whether changes in tumor vascular parameters could be detected in humans, and to assess whether CDP860 would be likely to increase the uptake of a concurrently administered small molecule in future studies. PATIENTS AND METHODS: Patients with advanced ovarian or colorectal cancer and good performance status received intravenous infusions of CDP860 on days 0 and 28. Patients had serial dynamic contrast-enhanced magnetic resonance imaging studies to measure changes in tumor vascular parameters. RESULTS: Three of eight patients developed significant ascites, and seven of eight showed evidence of fluid retention. In some patients, the ratio of vascular volume to total tumor volume increased significantly (P < .001) within 24 hours following CDP860 administration, an effect suggestive of recruitment of previously non-functioning vessels. CONCLUSION: These observations suggest that inhibition of PDGFR-beta might improve delivery of a concurrently administered therapy. However, in cancer patients, further exploration of the dosing regimen of CDP860 is required to dissociate adverse effects from beneficial effects. The findings challenge the view that inhibition of PDGF alone is beneficial, and confirm that effects of PDGFR kinase inhibition mediate, to some extent, the fluid retention observed in patients treated with mixed tyrosine kinase inhibitors.

Adult↗

Childhood injuries due to falls from apartment balconies and windows.

BACKGROUND: Falls from balconies and windows are an important cause of childhood injury. This study investigated the circumstances around such falls and attempted to identify possible measures for their prevention. POPULATION: Children <15 years living in Dallas County, Texas. METHODS: Each child treated because of a fall from a building in 1997-99 had information about the injury collected, and a parent was contacted to obtain further information. For apartment related falls, an attempt was made to visit the apartment to measure windows and balcony rails. RESULTS: Ninety eight children were injured in falls from buildings during the three year period; 39 (40%) were admitted to hospital. Seventy five of the falls (77%) involved apartments, and most occurred around noon or evening meal times. Among apartment falls, 39 (52%) fell from windows, 34 (45%) from balconies, and two (3%) from unknown sites. For more than two thirds of balcony related falls, the child fell from between the balcony rails, all of which were spaced more than 4 inches (10 cm) apart. On-site measurement showed the rails were an average of 7.5 inches (19 cm) apart; all of these apartments were built before 1984. For more than two thirds of window related falls, the window was situated within 2 feet (61 cm) of the floor. CONCLUSIONS: Two factors are important in falls from apartment windows and balconies: balcony rails more than 4 inches (10 cm) apart, and windows positioned low to the floor. Current building codes do not apply to older apartments, where most of these falls occurred. Nevertheless, these factors may be amenable to environmental modifications that may prevent most of these falls.

Accidental Falls↗

Metabolic profiles of dystrophin and utrophin expression in mouse models of Duchenne muscular dystrophy.

Metabolic profiles from (1)H nuclear magnetic resonance spectroscopy have been used to describe both one and two protein systems in four mouse models related to Duchenne muscular dystrophy using the pattern recognition technique partial least squares. Robust statistical models were built for extracts and intact cardiac tissue, distinguishing mice according to expression of dystrophin. Using metabolic profiles of diaphragm, models were built describing dystrophin and utrophin, a dystrophin related protein, expression. Increased utrophin expression counteracted some of the deficits associated with dystrophic tissue. This suggests the method may be ideal for following treatment regimes such as gene therapy.

Animals↗

Confusion: an ambiguous term in A&E practice.

The term 'confusion' can create conflicting images in terms of a patient's level of consciousness, awareness and ability to communicate effectively. In relation to Accident and Emergency (A&E) practice it is crucial that the nurse assessing the patient is not only taking into account the presenting clinical picture, but is also cognisant of the potential cumulative effects of physiological, psychological, pharmacological, sociological and environmental factors. Clearly, the assessment process should take these factors and the possible effects of the patient's journey to the A&E department into account when forming an opinion in respect of levels of consciousness. This paper will explore a number of potential co-factors, factors that could influence the patient's presentation and create an ambiguous misleading and conflicting picture unless all co-factors are considered.

Confusion↗

Immunization in rheumatic diseases of childhood: an audit of the clinical practice of British Paediatric Rheumatology Group members and a review of the evidence.

OBJECTIVES: To establish opinion and clinical practice of senior clinicians working with children with rheumatic diseases with regard to immunization and to determine whether or not this is in accordance with current recommendations. To review published guidelines on the subject and examine the evidence base supporting them. METHODS: A questionnaire was sent to all consultant members of the British Paediatric Rheumatology Group. Information on a variety of issues relating to immunization practice in children with rheumatic diseases was collected. A review of published guidelines and the medical literature on the subject was undertaken to assess current recommendations for immunization in patients on immunosuppressive agents and the evidence supporting these. RESULTS: A number of different sources of information are being used to decide whether or not to immunize patients with rheumatic diseases. Clinical practice varies between individuals. Areas of discordance include the doses of corticosteroids and disease-modifying drugs at which significant immunosuppression is felt likely to occur, the level of immunosuppression conferred by rheumatological diseases themselves and whether or not vaccination should be deferred in the presence of active disease. There was also variation in policy with regard to immunizations not part of the routine recommended schedule. CONCLUSIONS: There is variation in both opinion and clinical practice regarding immunization in children with rheumatic diseases amongst senior clinicians working in the field of paediatric rheumatology. This reflects the lack of consistency between various sets of published guidelines and their non-specificity for rheumatic diseases and their treatment, and the lack of published evidence on the safety and efficacy of different vaccines in these situations. Further research is indicated in the hope that more specific guidelines may be developed for this not uncommonly encountered area of uncertainty.

Arthritis, Juvenile↗

Imprinted genes and the coordination of fetal and postnatal growth in mammals.

A substantial proportion of genes that control fetal growth in placental mammals are imprinted. Imprinted genes can act in fetal tissues to regulate growth by cell proliferation, cell death and the make up of extracellular space. Imprinted growth-promoting genes such as Igf2 probably act predominantly in an endocrine fashion, thus coordinating organ growth with the growth of the organism. In overgrowth and growth deficiency syndromes, however, imprinted growth factors can act by more local mechanisms, resulting in disproportionate growth. In addition to controlling fetal growth directly and thereby determining the nutritional demand of the fetus, imprinted genes can also apparently limit the nutritional supply to the fetus through the placenta. Imprinted genes may also be involved in postnatal growth up to weaning.

Animals↗

Age-related changes in protein oxidation and proteolysis in mammalian cells.

Reactive oxygen species generated as by-products of oxidative metabolism, or from environmental sources, frequently damage cellular macromolecules. Proteins are recognized as major targets of oxidative modification, and the accumulation of oxidized proteins is a characteristic feature of aging cells. An increase in the amount of oxidized proteins has been reported in many experimental aging models, as measured by the level of intracellular protein carbonyls or dityrosine, or by the accumulation of protein-containing pigments such as lipofuscin and ceroid bodies. In younger individuals, moderately oxidized soluble cell proteins appear to be selectively recognized and rapidly degraded by the proteasome. An age-related accumulation of oxidized proteins could, therefore, be a result of declining activity of the proteasome. Previous research to investigate the notion of an age-related decline in the content and/or activity of the proteasome has generated contradictory results. The latest evidence, including our own recent findings, indicates that proteasome activity does, indeed, decline during aging as the enzyme complex is progressively inhibited by oxidized and cross-linked protein aggregates. We propose that cellular aging involves both an increase in (mitochondrial) oxidant production and a progressive decline in proteasome activity. Eventually so much proteasome is inactivated that oxidized proteins begin to accumulate rapidly and contribute to cellular dysfunction and senescence.

Animals↗

'Silent and censured travellers'? Patients' narratives and patients' voices: perspectives on the history of mental illness since 1948.

This article seeks to demonstrate how patients' oral testimony can usefully contribute to--and challenge--the history of mental illness in the second half of the twentieth century, through the use of the concept of narrative frames. This work has emerged from a broader study which seeks to examine shifts and continuities in the experiences of mental illness from the introduction of the NHS to the present day, through a study of Oxfordshire. Psychiatry itself and the historiography of psychiatry have in many ways silenced the patient or service user. Nevertheless, acceptable means of communication have always existed, and these are revealed through patients' narratives. In-depth analysis of 21 interviews with patients has led to the emergence of three key acceptable narratives or narrative frames, these being: stories of loss, tales of survival and self-discovery, and narratives of the self as patient. Through examination of three key frames by which patients and users have understood and presented their illness experiences, this article seeks to trace the interactions between the general and the particular, the social and the individual, and to contribute to a more nuanced understanding of the recent history of mental health and illness.

Communication Methods, Total↗

Impact of depressed mood on neuropsychological status in temporal lobe epilepsy.

OBJECTIVES: Depression is a common psychiatric complication of temporal lobe epilepsy. This study examined the effect of depressed mood on neuropsychological performance among patients with chronic temporal lobe epilepsy. METHODS: Seventy consecutive surgery candidates for medication resistant complex partial seizures of unilateral temporal lobe origin were assessed for psychiatric symptoms and underwent comprehensive neuropsychological assessment. RESULTS: Standardised psychiatric interview disclosed that 34% of the patient sample exhibited significant depression. Controlling for seizure frequency, patients with comorbid depression at the time of neuropsychological assessment exhibited significantly poorer performance on measures of intelligence, language, visuoperceptual ability, memory, and executive function. Within lateralised temporal lobe epilepsy groups, the adverse effects of depression on cognitive function were greater in patients with left temporal lobe compared with those with right temporal lobe epilepsy. In addition, depression seemed to be underrecognised and undertreated as none of the patients with epilepsy and comorbid depression were treated for their psychiatric condition at the time of admission for monitoring. CONCLUSIONS: Depression, a common psychiatric comorbidity among patients with chronic temporal lobe epilepsy, seems to be undertreated and to have adverse effects on cognitive functioning.

Adult↗

Juvenile idiopathic polyarticular arthritis and IgA deficiency in the 22q11 deletion syndrome.

Five patients with the 22q11 deletion syndrome (velocardiofacial syndrome) developed chronic inflammatory polyarticular arthritis. These new cases add to 8 previously reported and confirm the association. The arthritis in all cases was moderate to severe, but at least partially responsive to methotrexate and/or corticosteroids, and was clinically indistinguishable from juvenile idiopathic arthritis (JIA). Analysis of the total 13 patients indicates that 2 are rheumatoid factor positive, 6 are antinuclear antibody positive, 5 have subtle T cell deficiencies, and 6 have hypergammaglobulinemia. Of particular interest is the occurrence of IgA deficiency in 4 patients, including 2 from our own series. Although IgA deficiency is seen in both JIA (2-4%) and 22q11 deletion syndrome (2-4%), the prevalence of low IgA in this series (31%) is much greater than expected. This phenomenon and the true association of inflammatory arthritis and a chromosome deletion disorder provides further evidence of important genetic factors in the pathogenesis of JIA.

Adolescent↗

Measurement of cerebral microvessel diameters after embolic stroke in rat using quantitative laser scanning confocal microscopy.

Perfusion of the microcirculation after stroke is central to preserving neuronal function and improving functional outcome. Using laser scanning confocal microscopy (LSCM) and a novel computer software program, MIRAGE, we measured a reduction in cerebral microvessel diameter after 1 and 4 h of embolic middle cerebral artery (MCA) occlusion. The methodology used by MIRAGE for measurement of blood vessel diameter involves a linearly applied spherical inflation technique. Three-dimensional quantitative analysis revealed a significant (P<0.05) mean 10-12% reduction in vessel diameter in the ipsilateral cortex when compared to the homologous region in the contralateral hemisphere. This reduction was seen only in the cortex and not the striatum. A larger reduction in mean vessel diameter in the ipsilateral cortex, 16-30% (P<0.05) was observed when compared to sham control rats. These results are in strong agreement with other studies using different stroke models and imaging techniques. Our work represents a novel application of LSCM technology to the three dimensional investigation of microvessel diameter changes in acute stroke and identifies its potential as an important tool for investigation of cerebral pathology.

Animals↗

Sequence conservation and variability of imprinting in the Beckwith-Wiedemann syndrome gene cluster in human and mouse.

In human and mouse most imprinted genes are arranged in chromosomal clusters. This linked organization suggests coordinated mechanisms controlling imprinted expression. We have sequenced 250 kb in the centre of the mouse imprinting cluster on distal chromosome 7 and compared it with the orthologous Beckwith-Wiedemann gene cluster on human chromosome 11p15.5. This first comparative imprinting cluster analysis revealed a high structural and functional conservation of the six orthologous genes identified. However, several striking differences were also discovered. First, compared with the mouse the human sequence is approximately 40% longer, mostly due to insertions of two large repetitive clusters. One of these clusters encompasses an additional gene coding for a homologue of the ribosomal protein L26. Second, pronounced blocks of unique direct repeats characteristic of imprinted genes were only found in the human sequence. Third, two of the orthologous gene pairs Tssc4/TSSC4 and Ltrpc5/LTRPC5 showed apparent differences in imprinting between human and mouse, whereas others like Tssc6/TSSC6 were not imprinted in either organism. Together these results suggest a significant functional and structural variability in the centre of the imprinting cluster. Some genes escape imprinting in both organisms whereas others exhibit tissue- and species-specific imprinting. Hence the control of imprinting in the cluster appears to be a highly dynamic process under fast evolutionary adaptation. Intriguingly, whereas imprinted genes within the cluster contain CpG islands the non-imprinted Ltrpc5 and Tssc6/TSSC6 do not. This and additional comparisons with other imprinted and non-imprinted regions suggest that CpG islands are key features of imprinted domains.

Amino Acid Sequence↗