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J W Gregory

Publications and source records attributed to J W Gregory.

At least 37 records · Page 2Linked to original sources
PubMed2003

Morphological determinants of femoral strength in growth hormone-deficient transgenic growth-retarded (Tgr) rats.

UNLABELLED: The extent to which childhood GHD affects adult fracture risk is unclear. We measured femoral strength in adult transgenic growth-retarded rats as a model of GHD. Long-term, moderate GHD was accompanied by endocrine and morphometric changes consistent with a significant reduction in femoral strength. INTRODUCTION: Childhood growth hormone deficiency (GHD) is associated with osteopenia, but little is known about its effects on subsequent adult bone strength and fracture risk. MATERIALS AND METHODS: We have therefore measured femoral strength (failure load measured by three-point bending) in a new model of moderate GHD, the transgenic growth-retarded (Tgr) rat at 15, 22-23, and 52 weeks of age, and have quantified potential morphological and endocrine determinants of bone strength. RESULTS: Skeletal growth retardation in Tgr rats was accompanied by a sustained reduction in the anterior-posterior diameter of the femoral cortex, whereas mid-diaphyseal cortical wall thicknesses were largely unaltered. Total femoral strength was significantly impaired in Tgr rats (p < 0.01), and this impairment was more pronounced in males than females. Compromised bone strength in Tgr rats could not be accounted for by the reduction in mechanical load (body weight) and was not caused by impairment of the material properties of the calcified tissue (ultimate tensile stress), despite marked reductions in femoral mineral density (areal bone mineral density; p < 0.001). Microcomputerized tomographical analysis revealed significant modification of the architecture of trabecular bone in Tgr rats, with reductions in the number and thickness of trabeculae (p < 0.05) and in the degree of anisotropy (p < 0.01). The marked reduction in plasma insulin-like growth factor-1 in Tgr rats was accompanied by the development of high circulating leptin levels (p < 0.01). CONCLUSION: These results show that the changes in endocrinology and bone morphology associated with long-term moderate GHD in Tgr rats are accompanied by changes consistent with a significant reduction in the threshold for femoral fracture.

Age Factors↗
PubMed2002

In vitro effects of chemotherapeutic agents on human osteoblast-like cells.

Osteopenia is a complicating problem that may occur during and after treatment for childhood malignancy. Clinical studies suggest that chemotherapeutic agents directly affect osteoblasts in vivo. Since combinations of agents are used for treatment, we individually investigated the chemosensitivity of human osteoblast-like cells to 11 of the chemotherapeutic agents used. The relative chemosensitivity of osteoblast-like cells representing different stages of cell differentiation was also examined. Cell numbers were evaluated following culture of an established human osteoblast-like cell line (MG63) for 3 days with clinically relevant concentrations of the chemotherapeutic agents. The chemosensitivity of MG63 cells was compared to that of a human osteoprogenitor cell line (HCC1) and primary osteoblast-like (HOB) cells derived from pediatric bone. Cell numbers were reduced by all agents in all cell types, although there was a varied response between agents at equimolar concentrations. In MG63 cells the lowest concentration of agent significantly reducing cell numbers varied between agents, for example, methotrexate (10(-7) M), vincristine (10(-9) M), and etoposide (10(-7) M) (all P <0.01). The less differentiated osteoblast phenotypes were significantly more chemosensitive at equimolar concentrations of methotrexate, vincristine, asparaginase, and dexamethasone than more differentiated phenotypes (all P <0.01). Furthermore, four agents significantly increased alkaline phosphatase (AP) activity in HOB cells. We conclude that individual chemotherapeutic agents added to osteoblast cell cultures reduce cell numbers, with osteoblast precursor cells being preferentially depleted. These results suggest that most of the agents may contribute to osteopenia in childhood malignancy by direct effects on cell numbers.

Alkaline Phosphatase↗
PubMed2002

In vitro effects of combination chemotherapy on osteoblasts: implications for osteopenia in childhood malignancy.

Clinical studies suggest that combination chemotherapy adversely affects bone metabolism and in vitro studies have demonstrated that a reduction in osteoblast numbers results in diminished bone formation. The aim of this study was to investigate the in vitro effects of combinations of chemotherapeutic agents on primary human osteoblast-like (hOB) cell numbers and apoptosis, and to assess the ability of hOBs and osteoprogenitor (HCC1) cells to recover from prior treatment with chemotherapy. As glucocorticoids are frequently administered during treatment with cytotoxic agents, we evaluated whether glucocorticoids influence the chemosensitivity of hOB and human osteosarcoma (MG63) cells. Culture with clinically relevant concentrations of the individual chemotherapeutic agents reduced hOB cell numbers compared with control (p < 0.01) and also increased the numbers of apoptotic cells (p < 0.05). Potentiation of cytotoxicity was observed when agents were given in combination, thus further reducing cell numbers, and this effect was greatest when vincristine was given in combination with asparaginase. Following culture with a chemotherapeutic agent, there was greater recovery of hOB compared with HCC1 cell numbers (p < 0.01). Pretreatment with glucocorticoids ameliorated the adverse effects of chemotherapeutic agents on hOB and MG63 cell numbers and apoptosis (p < 0.05). We conclude that the use of combination chemotherapy contributes to osteopenia in childhood malignancy by a reduction in osteoblast numbers. However, this effect may be attenuated by the concomitant use of glucocorticoids.

Adolescent↗
PubMed2001

Assessment of the effects of intensive training of community based staff in the screening of children for disorders of growth and puberty.

INTRODUCTION: The effects of an intensive training programme involving screening of children for disorders of growth and puberty for community based nursing and medical staff employed by Cardiff Community Healthcare NHS Trust were audited to assess the impact of this training on referrals to the local hospital based growth clinic. METHOD: Referrals from community based staff to the growth clinic of patients living in the geographical area in which staff underwent training were compared with those from general practitioners in the 18 months prior to and following the training programme. Hospital notes were available for 209 of 254 (82.2%) patients identified. We excluded 112 referrals as they did not have a problem relating to growth or puberty or were inter-hospital referrals. Hence 97 referrals were included in the final audit. RESULTS: Forty referrals occurred prior to compared with 57 following the training programme. The number of referrals from community based staff increased threefold during the six months immediately following the training programme but then returned to the previous level. There were no differences in age or height standard deviation scores at referral between groups at any time. The proportion of children referred from the community with significant abnormalities of growth or puberty (for example, hypothyroidism or precocious puberty) increased from two of 15 referrals to six of 30 referrals following the training programme. CONCLUSIONS: Intensive training in screening for disorders of growth and puberty can increase the number of referrals of children with significant pathology but at the cost of increased total number of referrals. The increase in referrals is not sustained with time, suggesting continued training is necessary.

Adolescent↗
PubMed2000

Proliferative response of different human osteoblast-like cell models to proinflammatory cytokines.

Children with inflammatory bowel disease are known to be at risk of osteopenia. The cause of this osteopenia is likely to be multifactorial, but the inflammatory process with its characteristic overproduction of cytokines has been implicated. To investigate this possible contribution of the disease activity to the development of osteopenia, we performed in vitro assays of the proliferation of osteoblast-like cells of differing origins in response to the inflammatory cytokines tumor necrosis factor-alpha and IL-1/beta. Osteoblast-like cells derived from pediatric bone explants, adherent stromal cells derived from bone marrow (osteoprogenitors), MG-63 osteosarcoma cells, and SV-40 virally transformed osteoprogenitor cells (HCC1) were studied. Tumor necrosis factor-alpha stimulated the proliferation of cells in primary cultures (i.e. from explants and marrow samples) in a linear, dose-dependent manner. In contrast, inhibition of proliferation was observed with the established cell lines (MG-63 and HCC1). IL-1beta stimulated proliferation of all cells apart from the immortalized human bone marrow cell line, HCC1, in which case potent inhibition was observed. We conclude that proinflammatory cytokines are potent regulators of osteoblast-like cell proliferation, and that the responses are specific to cell type. The opposite results obtained with established cell lines compared with the primary cultures suggest that careful consideration should be given to choosing the most suitable cell line for in vitro studies relating to in vivo mechanisms predisposing to osteopenia.

Adolescent↗
PubMed1999

Metabolic effects of discontinuing growth hormone treatment.

AIMS: To evaluate the effects of discontinuing growth hormone (GH) treatment on energy expenditure and body composition, which might help predict those most likely to benefit from early reintroduction of GH treatment in young adult life. METHODS: Body composition was calculated from skinfold thicknesses and dual energy x ray absorptometry (DXA). Resting metabolic rate (RMR) and whole body bone mineral content (BMC) were also measured. Measurements were made before stopping treatment, at discontinuation of GH treatment, and two weeks, six months, and one year later in 11 adolescents with growth hormone deficiency (GHD) and five adolescents without GHD who were treated with GH. Measurements were compared with 10 healthy controls, in whom measurements were repeated one year later. RESULTS: During the nine months before discontinuation of GH there were no changes in body composition, RMR, or BMC of patients with GHD, nor differences when compared with controls. RMR was reduced by 11.3 kJ/kg fat free mass two weeks after stopping GH in GHD patients and remained suppressed thereafter compared with controls. Percentage body fat increased by 4.3%/year in patients with GHD after discontinuing GH, whereas no changes were noted in control or non-GHD patients at one year. The patients experiencing the greatest reductions in RMR/kg fat free mass at six months showed the largest increases in body fat at one year. No change in BMC was noted in patients one year after stopping treatment. CONCLUSION: Important metabolic changes occur early after discontinuing GH treatment. In patients whose growth is complete, these changes might be used to predict those most likely to benefit from continuation of GH treatment into adult life.

Adolescent↗
PubMed1999

Relative osteopenia after treatment for acute lymphoblastic leukemia.

Osteoporosis in adult life is associated with a significant morbidity and may be predisposed to by osteopenia and failure to reach peak bone mass in childhood. Children treated for acute lymphoblastic leukemia (ALL) may be at risk of osteopenia as a result of previous therapy or as a consequence of the disease process itself. Dual energy x-ray absorptiometry measurements of bone mineral content (BMC) for the whole body and at the lumbar spine and hip were taken in 35 (14 male) long-term survivors of ALL and compared with results in 20 (10 male) survivors of other malignancies and 31 (17 male) healthy sibling controls. The measured BMC was expressed as a percentage of a predicted value derived from the control group and based on the variables that had influence upon it. BMC (%) was reduced at the spine in the ALL group compared with controls [92.4 (8.0)% versus 100.4 (9.7)%, respectively; p < 0.005] and at the hip compared with both other malignancies and controls [89.0 (11.5)% versus 96.1 (11.7)% and 100.4 (9.2)%, respectively; p < 0.0005]. Increasing length of time off therapy was associated with a significant increase in %BMC at both the spine and the hip. For the spine, this association was significantly different between the ALL group and other malignancies, suggesting that any gain in %BMC after therapy was slower in children treated for ALL. Both exercise capacity and levels of physical activity were correlated with %BMC at the hip (r = 0.44, p < 0.001 and r = 0.29, p < 0.01, respectively). Previous exposure to methotrexate, ifosfamide, and bleomycin was associated with a reduction in %BMC at the spine. Exposure to 6-mercaptopurine and cisplatin was associated with a reduction at the hip. In conclusion, children treated for ALL are osteopenic. The mechanism is probably multifactorial but is partially related to previous chemotherapy, limited exercise capacity, and relative physical inactivity.

Adult↗
PubMed1998

Congenital hypothyroidism in Wales (1982-1993): demographic features, clinical presentation and effects on early neurodevelopment.

OBJECTIVE: Neonatal screening for congenital hypothyroidism (CH) was introduced in Wales in 1982. The aim of the study was to evaluate the demographic features and characteristics of infants identified during the first 12 years of screening and their neurodevelopmental progress in the first 2 years of life. DESIGN: Prospective collection of biochemical and clinical data (including results of Griffiths Mental Development Scales) obtained from questionnaires sent to paediatricians responsible for the ongoing clinical care of children with CH. PATIENTS: In Wales, between 1982 and 1993, 136 infants with primary congenital hypothyroidism (CH) were identified by the neonatal screening programme. RESULTS: Of all new-borns, 99.8% were screened and the prevalence of CH was 1 in 3279 (1 in 2473 girls and 1 in 4770 boys). The prevalence of CH was increased in North Wales. CH was associated with increased birth weight (48.5% of infants weighed greater than 3.5 kg) and an increased prevalence of non-thyroidal congenital abnormalities (8%) and congenital heart disease (3%). Isotope scanning demonstrated an increased prevalence of normal or enlarged thyroid glands and fewer ectopic glands compared to those reported in other studies. The mean developmental quotients (DQs) for individual subsets of intellectual and behavioural functioning in children with CH aged 1 and 2 years were all above 100 (range: 103.5-111.9). In subjects with absent thyroids, these DQs were correlated with the serum concentrations of free thyroxine before treatment. CONCLUSIONS: The demographic features of infants with congenital hypothyroidism born in Wales are similar to those reported from other European studies although there are marked regional variations in prevalence within Wales for which there is no apparent explanation. The median age of starting therapy was 17 days and compares favourably with other screening programmes. The overall mental development of Welsh children aged 1 and 2 years with congenital hypothyroidism identified by neonatal screening is satisfactory.

Congenital Abnormalities↗
PubMed1998

Measured and predicted bone mineral content in healthy boys and girls aged 6-18 years: adjustment for body size and puberty.

Dual-energy X-ray absorptiometry (DEXA) is a rapid and precise technique for the assessment of bone mineralization in children. Interpretation of the results in growing children is complex as results are influenced by age, body size (height and weight) and puberty. Conventionally, bone mineral data derived from DEXA have been presented as an areal density [BMD; bone mineral content (BMC, g)/projected bone area (BA, cm2)], yet this fails to account for changes in BMC that result from changes in age, body size or pubertal development. Measurement of BMC and BA of the whole body, lumbar spine and left hip were made in 58 healthy boys and girls using DEXA. The relationship between BMC and BA was curvilinear, with the best fit being that of a power model (BMD = BMC/BAlambda, where lambda is the exponent to which BA is raised in order to remove its influence on BMC). The value of lambda changed when measures of body size and puberty were taken into account (e.g. for lumbar spine from 1.66 to 1.49). Predictive formulae for BMC were produced using regression analysis and based on the variables of age, body size and pubertal development. This provides a method for interpreting the measured BMC which is independent of such variables and a constant reference range for children aged 6-18 y.

Absorptiometry, Photon↗
PubMed1998

Daily energy expenditure and physical activity in survivors of childhood malignancy.

Changes in body composition, in particular the onset of obesity, may result from reductions in total daily energy expenditure (TDEE) as a consequence of relative physical inactivity. Children previously treated for acute lymphoblastic leukemia (ALL) become obese, yet the mechanism remains undefined. TDEE and physical activity levels [PAL = TDEE/basal metabolic rate (BMR)] were measured in 34 long-term survivors of ALL and compared with results from 21 survivors of other malignancies and 32 healthy sibling control subjects using the flex-heart rate technique. Body composition was measured by dual energy x-ray absorptiometry. The median TDEE was reduced in the ALL group (150 kJ x kg d(-1)) compared with other malignancies and controls (207 and 185 kJ x kg d(-1), respectively, p < 0.01). This reduction was accounted for mainly by a relative decrease in the PAL of the ALL group (1.24) compared with both other malignancies and controls (1.58 and 1.47, respectively, p < 0.01). TDEE and PAL were correlated with percentage body fat (r = -0.39, p < 0.001 and r = -0.24, p < 0.05, respectively). Obesity in survivors of ALL may, in part, be explained by a reduction in TDEE as a consequence of reduced PAL. The cause of such reduction is uncertain.

Adolescent↗
PubMed1997

Relationship between cardiopulmonary response to exercise and adiposity in survivors of childhood malignancy.

Many long term sequelae result from previous treatment for malignancy in childhood. However, little information exists on cardiopulmonary response and energy expenditure during exercise and their possible associations with excess body fat. Measurements of body composition and exercise capacity both at low intensity and maximal aerobic capacity were made on 56 long term survivors of childhood malignancy (35 survivors of acute lymphoblastic leukaemia (ALL) and 21 survivors of other malignancies) and 32 siblings acting as controls. Female survivors of ALL had significantly greater mean (SD) body fat than survivors of other malignancies and siblings (32.5 (6.4)% v 24.3 (4.4)% and 26.3 (8.5)% respectively, p < 0.005). Energy expenditure at low intensity exercise was reduced in survivors of ALL, and negatively correlated with body fat after controlling for weight (partial r range -0.21 to -0.47, p < 0.05). Stroke volume, measured indirectly, was reduced and heart rate raised in ALL survivors at sub-maximal exercise levels. Peak oxygen consumption was significantly reduced in girls and boys treated for ALL compared with siblings (30.5 v 41.3 ml/kg/min for girls, p < 0.05 and 39.9 v 47.6 ml/kg/min for boys, p < 0.05 respectively). Reduced exercise capacity may account in part for the excess adiposity observed in long term survivors of ALL.

Adolescent↗
PubMed1997

Inflammatory bowel disease and predisposition to osteopenia.

The prevalence of osteopenia in children with inflammatory bowel disease (IBD) is unknown. The effect of nutritional state, disease activity, and steroid therapy on bone mineral content (BMC) of whole body, lumbar spine, and left femoral neck measured by dual energy x ray absorptiometry in 32 children with IBD was assessed by comparison with 58 healthy local school children. Using the control data, a predicted BMC was calculated taking into account bone area, age, height, weight, and pubertal stage. The measured BMC in children with IBD was expressed as a percentage of this predicted value (% BMC). Mean (SD) % BMC was significantly reduced for the whole body and left femoral neck in the children with IBD (97.0 (4.5)% and 93.1 (12.0)% respectively, p < 0.05). Of the children with IBD, 41% had a % BMC less than 1 SD below the mean for the whole body and 47% at the femoral neck. Reduction in % BMC was associated with steroid usage but not with the magnitude of steroid dose, disease activity, or biochemical markers of bone metabolism. In conclusion, osteopenia is relatively common in childhood IBD and may be partly related to the previous use of steroids.

Adolescent↗
PubMed1997

Phenotypic diversity in siblings with partial androgen insensitivity syndrome.

The androgen insensitivity syndrome is a heterogeneous disorder with a wide spectrum of phenotypic abnormalities, ranging from complete female to ambiguous forms that more closely resemble males. The primary abnormality is a defective androgen receptor protein due to a mutation of the androgen receptor gene. This prevents normal androgen action and thus leads to impaired virilisation. A point mutation of the androgen receptor gene affecting two siblings with partial androgen insensitivity syndrome is described. One had cliteromegaly and labial fusion and was raised as a girl, whereas the other sibling had micropenis and penoscrotal hypospadias and was raised as a boy. Both were shown to have the arginine 840 to cysteine mutation. The phenotypic variation in this family is thus dependent on factors other than abnormalities of the androgen receptor gene alone.

Female↗
PubMed1997

Auditing paediatric diabetes care and the impact of a specialist nurse trained in paediatric diabetes.

AIMS: To define outcome measures for auditing the clinical care of children and adolescents with insulin dependent diabetes mellitus (IDDM) and to assess the benefit of appointing a dedicated paediatric trained diabetes specialist nurse (PDSN). METHODS: Retrospective analysis of medical notes and hospital records. Glycaemic control, growth, weight gain, microvascular complications, school absence, and the proportion of children undergoing an annual clinical review and diabetes education session were assessed. The effect of the appointment of a PDSN on the frequency of hospital admission, length of inpatient stay, and outpatient attendance was evaluated. RESULTS: Children with IDDM were of normal height and grew well for three years after diagnosis, but grew suboptimally thereafter. Weight gain was above average every year after diagnosis. Glycaemic control was poor at all ages with only 16% of children having an acceptable glycated haemoglobin. Eighty five per cent of patients underwent a formal annual clinical review, of whom 16% had background retinopathy and 20% microalbuminuria in one or more samples. After appointing the PDSN the median length of hospital stay for newly diagnosed patients decreased from five days to one day, with 10 of 24 children not admitted. None of the latter was admitted during the next year. There was no evidence of the PDSN affecting the frequency of readmission or length of stay of children with established IDDM. Non-attendance at the outpatient clinic was reduced from a median of 19 to 10%. CONCLUSIONS: Outcome measures for evaluating the care of children with IDDM can be defined and evaluated. Specialist nursing support markedly reduces the length of hospital stay of newly diagnosed patients without sacrificing the quality of care.

Adolescent↗
PubMed1997

Two novel mutations in the thyrotropin (TSH) receptor gene in a child with resistance to TSH.

The TSH receptor is a G protein-coupled receptor that mediates the effects of TSH in thyroid development, growth, and synthetic function. We report here that a child with features of TSH resistance, including markedly increased serum TSH concentrations and low normal thyroid hormone levels, is a compound heterozygote for two novel mutations in the TSH receptor gene. One allele has a G to A transition corresponding to an arginine to glutamine change at codon 109 (R109Q) in the extracellular domain of the receptor. The other allele has a G to A transition corresponding to a premature termination codon at tryptophan 546 (W546X) in the fourth transmembrane segment. Each parent is heterozygous for one mutation, and both parents have normal thyroid function. Cells transiently transfected with the R109Q mutant exhibited reduced membrane binding of [125I]TSH and impaired signal transduction in response to TSH. In contrast, the W546X mutant was nonfunctional, with negligible membrane radioligand binding. Our findings indicate that a single normal TSH receptor allele is sufficient for normal thyroid function, but that the compound abnormality in the proband leads to TSH resistance.

Amino Acid Sequence↗
PubMed1997

Visual function in young IDDM patients over 8 years of age. A 4-year longitudinal study.

OBJECTIVE: To carry out a longitudinal study of visual functions in young patients over the age of 8 years with IDDM and to assess the impact of metabolic control on the presence of diabetic retinopathy. RESEARCH DESIGN AND METHODS: There were 37 young IDDM patients from the Paediatric and Adolescent Clinic at the University Hospital of Wales studied annually for 4 years, with a control group of 24 healthy subjects observed over a 2-year period. Assessment of visual functions included visual acuity, color vision, and contrast sensitivity. Ophthalmoscopy and retinal photography were used to determine the presence or absence of diabetic retinopathy. In addition, pubertal status and metabolic control (glycosylated hemoglobin) were determined at each visit. RESULTS: Patients with IDDM demonstrate abnormal color vision and contrast sensitivity compared with the control group (P < 0.05), but visual acuity was unaffected. Visual functions were not significantly different between those IDDM patients with and without retinopathy. After 4 years, diabetic retinopathy was present in 43% of the group and was related to diabetes duration and metabolic control (P < 0.05). CONCLUSIONS: Visual function testing could not distinguish between those IDDM patients with and without retinopathy, but the color vision and contrast sensitivity in those with IDDM were significantly impaired compared with the control group. The presence of retinopathy was related to the duration of diabetes and metabolic control. It is important to ensure that good glycemic control and regular attendance for retinopathy screening is encouraged in the adolescent patients.

Adolescent↗