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Marsha L Davenport

Publications and source records attributed to Marsha L Davenport.

11 recordsLinked to original sources
PubMed2006

Differences in follicle-stimulating hormone secretion between 45,X monosomy Turner syndrome and 45,X/46,XX mosaicism are evident at an early age.

CONTEXT: Little information exists regarding FSH values in very young girls with Turner syndrome (TS). OBJECTIVES: The objective of the study was to evaluate the pattern, natural progression, and karyotype-related differences in FSH secretion in young, prepubertal girls with TS. STUDY DESIGN: FSH was measured at study entry and annually for 2 yr. SETTING: The Toddler Turner study was conducted at 11 U.S. pediatric endocrine centers. STUDY PARTICIPANTS: Eighty-eight girls with karyotype-proven TS aged 9 months to 4 yr participated in the study. MAIN OUTCOME MEASURES: By-karyotype differences in FSH concentration and age-related changes in FSH were measured. RESULTS: Mean (+/- SD) FSH was markedly elevated in the 45,X (n = 56: 68.3 +/- 36.0 IU/liter) and Other groups [n = 15 (excluding three subjects with Y-containing karyotypes): 52.7 +/- 50.8 IU/liter] but was minimally elevated in girls with 45,X/46,XX mosaicism (n = 14: 10.1 +/- 13.5 IU/liter, P < 0.005 both comparisons). Over the 2-yr period, FSH declined in the 45,X group (-13.4 IU/liter.yr, P < 0.0001). Nonetheless, only three of 159 FSH values fell within normal range for age at any time during the 2-yr study. FSH decline was similar in the Other group (-14.3 IU/liter.yr, P = 0.0032). In contrast, no significant decrease in FSH with age was observed in the 45,X/46,XX group. CONCLUSIONS: In contrast to the original report of FSH concentrations in individuals with TS, this study demonstrates distinct differences in patterns of FSH secretion between young girls with monosomy TS, who have persistent elevation of FSH to age 6 yr, and those with 45,X/46,XX mosaicism, whose FSH values suggest retained ovarian function in the majority. These findings have implications for patient management and family counseling.

Aging↗
PubMed2006

Evidence for early initiation of growth hormone and transdermal estradiol therapies in girls with Turner syndrome.

Results from the first randomized, controlled trial of growth hormone (GH) therapy in girls with Turner syndrome (TS) followed to final height firmly establish that GH increases final adult stature. It is widely believed that the efficacy of GH is dependent upon the duration of therapy and dosing (longer duration and higher dose give taller final height). In a recent observational study involving more than 1500 French girls with TS, multivariate analyses demonstrated that the age at initiation of GH therapy accounted for a large percentage of the variance (44%) in response. Age at initiation of estrogen therapy was the second most important factor in determining GH effect (later initiation, taller final height), accounting for 22% of the variance. Overall, 0.3 cm in adult height was gained for every year that estrogen therapy was delayed. However, analyses of the French data restricted to patients with induced puberty revealed that those treated with percutaneous estradiol attained a height 2.1cm taller than those using oral estradiol or other estrogen preparations. In another study, girls receiving GH therapy (n=14) who were randomized to receive intramuscular (IM) depot estradiol early (12.0-12.9 years) attained at least as much height as those who initiated it late (14.0-14.9 years). These results are consistent with the observations in adult women that oral estrogens decrease IGF-I serum levels and suppress the IGF-independent metabolic effects of GH, while transdermal estrogens do not. Taken together, these studies suggest that girls with TS should begin GH therapy as soon as growth failure is demonstrated and that puberty should be induced with transdermal or IM estradiol. Girls for whom height is normalized with GH therapy in early childhood have the opportunity to undergo puberty at an age-appropriate time and still achieve a normal adult stature.

Administration, Cutaneous↗
PubMed2006

Gonadotropin secretion in girls with turner syndrome measured by an ultrasensitive immunochemiluminometric assay.

BACKGROUND/AIM: Gonadotropin levels measured by radioimmunoassays are high in girls with Turner syndrome (TS), but overlap significantly with those of normal girls. We hypothesized that gonadotropin levels would be above the normal range in TS when measured by ultrasensitive assays. METHODS: Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were measured in 68 TS, and 133 control girls using ultrasensitive immunochemiluminometric assays (ICMA). RESULTS: FSH levels in TS and normal girls were highest in early childhood (56.0 +/- 39.7 and 2.3 +/- 1.8 IU/l, respectively), declined at 6-10 years of age (11.3 +/- 13.1 and 1.8 +/- 0.9 IU/l, respectively), and then increased again (104.4 +/- 68.9 and 4.9 +/- 2.4 IU/l, respectively). FSH was in the normal range on 11 of 27 occasions in TS girls with ages 5-10 years, and on 3 of 44 occasions in >10 years. Although average LH values were higher than those of controls, they often overlapped the normal range. CONCLUSION: A significant number of TS girls have normal gonadotropins by ICMA. Spontaneous gonadotropin levels are not an adequate screening test for the diagnosis of TS but may prove useful for predicting the gonadal function and determining the appropriate timing of estrogen replacement therapy.

Adolescent↗
PubMed2006

Visuospatial executive function in Turner syndrome: functional MRI and neurocognitive findings.

Turner syndrome is a genetic disorder that results from an abnormal or missing X chromosome in females and is typically associated with impairments in visuospatial, but not verbal, information processing. These visuospatial processing impairments may be exacerbated with increased task demands, such as those engaged during working memory (WM). While previous studies have examined spatial WM function in Turner syndrome, none have directly compared the neural correlates of spatial and verbal WM processes across the encoding, maintenance and retrieval phases. We employed both neurocognitive assessments and functional MRI (fMRI) to examine the neural circuitry underlying both verbal and visuospatial WM functions in individuals with Turner syndrome and normal controls. We furthermore examined the vulnerability of task-related fMRI activation to distracters presented during WM maintenance. Fifteen healthy female volunteers and eight individuals with Turner syndrome performed a delayed-response WM task during fMRI scanning. Neurocognitive tests revealed impaired performance across both verbal and spatial domains in Turner syndrome, with greater impairment on tasks with WM demands. Frontoparietal regions in controls showed significantly sustained levels of activation during visuospatial WM. This sustained activation was significantly reduced in the group with Turner syndrome. Domain-specific activation of temporal regions, in contrast, did not differ between the two groups. Sensory distraction during the WM maintenance phase did not differentially alter frontoparietal activation between the two groups. The results reveal impaired frontoparietal circuitry recruitment during visuospatial executive processing in Turner syndrome, suggesting a significant role for the X chromosome in the development of these pathways.

Adolescent↗
PubMed2006

Continuous subcutaneous glucose monitoring in children with type 1 diabetes mellitus: a single-blind, randomized, controlled trial.

BACKGROUND: Tight glycemic control delays the long-term complications of type 1 diabetes mellitus (T1DM) but increases the risk for hypoglycemia. The continuous glucose-monitoring system (CGMS) provides blood glucose (BG) readings every 5 min, and its accuracy and reliability has been established in adults. However, there are limited data on its efficacy and safety in children. The purpose of this study was to determine if CGMS use improves metabolic control in children with T1DM. METHODS: Twenty-seven children (12 male) with T1DM participated in this single-blind, randomized, controlled trial. Participants (age: 11.4 +/- 3.7 (mean +/- SD) yr, range: 7-17 yr) were randomized to an intervention group (n = 18) or a control group (n = 9). Both groups wore the CGMS for 72-h periods at 0, 2, and 4 months. Adjustments in therapy for the intervention group were based on both CGMS and self-monitoring of BG (SMBG) data, while only SMBG data were used for the control group. Hemoglobin A1c (HbA1c) was determined at 0, 2, 4, and 6 months. The change in HbA1c from 0 to 6 months (HbA1c(Delta1-4)) and mean daily area under the CGMS curve for glucose <70 mg/dL area under the curve (AUC(<70)) were compared between groups. RESULTS: At study entry, HbA1c levels were similar in the intervention and control groups (8.4 +/- 0.98 and 8.8 +/- 0.86%, respectively; p = 0.12) but were significantly lower in the intervention group compared with the control group at study completion (7.8 +/- 0.88 and 8.6 +/- 0.95%, respectively; p = 0.02). The decrease in HbA1c of 0.61 +/- 0.68% in the intervention group was statistically significant (p = 0.03), whereas the decrease in HbA1c of 0.28 +/- 0.78% in the control group was not. Nonetheless, the differences in HbA1c(Delta1-4) between groups did not reach statistical significance (p = 0.13). There was no statistically significant difference in AUC(<70) between study groups (p = 0.18). CONCLUSION: CGMS use may improve metabolic control in children with T1DM without increasing the risk for hypoglycemia.

Adolescent↗
PubMed2005

Central obesity, the metabolic syndrome, and plasminogen activator inhibitor-1 in young adults.

PURPOSE: To determine the association of central obesity with the components of the metabolic syndrome (i.e., hyperinsulinemia, hypertension, hypertriglyceridemia, low levels of high-density lipoprotein cholesterol [HDL-C]) and plasma levels of plasminogen activator inhibitor-1 (PAI-1) in young adults. We hypothesized that central obesity as determined by waist circumference would be predictive of components of the metabolic syndrome and of PAI-1. DATA SOURCES: Participants in this descriptive study consisted of 85 healthy young adults aged 19-22 years, 62% women who fasted for 12 h prior to data collection in the General Clinical Research Center at a major university hospital medical center in the southeastern United States. CONCLUSIONS: The majority of the participants had one or more components of the metabolic syndrome (n= 43, 51%). Central obesity was present in 14.1% and was more common in women than men (chi(2)= 5.11; p= 0.021). Central obesity was significantly and positively correlated with elevated blood pressure (BP) and levels of insulin and PAI-1 while being negatively correlated with HDL-C. In multiple regression analyses, diastolic BP, insulin, and HDL-C were predictors of waist circumference (R(2)= 0.615). In a separate multiple regression, PAI-1 was predicted by waist circumference (R(2)= 0.331). IMPLICATIONS FOR PRACTICE: Many otherwise healthy young adults have one or more components of the metabolic syndrome. Assessment and institution of preventative measures for obesity and the components of the metabolic syndrome should begin in childhood. Furthermore, determination of waist circumference especially in young women may aid the practitioner to identify those at risk for the metabolic syndrome earlier in their disease trajectory. Furthermore, insulin resistance is believed to occur initially in the trajectory of the metabolic syndrome, making it a principal contender for suitable interventions to reduce risk for both type 2 diabetes and cardiovascular disease (CVD). Homeostatic model assessment for insulin resistance was used to assess for insulin resistance among the euglycemic participants. Recording the presence of insulin resistance will aid the practitioner in determining if a low-risk patient is in peril for development of type 2 diabetes and/or CVD. Early cardiovascular risk recognition is vital to clinical practice as it allows more time for the practitioner to counsel patients for the essential planning needed to make lifestyle changes.

Adipose Tissue↗
PubMed2004

Ascertainment bias in Turner syndrome: new insights from girls who were diagnosed incidentally in prenatal life.

OBJECTIVE: To evaluate differences in phenotype and other clinical features between patients who have Turner syndrome diagnosed incidentally (on the basis of a prenatal karyotype performed for reasons unrelated to suspicion of Turner syndrome, eg, advanced maternal age) or traditionally (on the basis of either a prenatal karyotype performed for abnormal ultrasound findings or a postnatal karyotype performed for clinical findings suggesting Turner syndrome). METHODS: Analysis was performed on baseline data from 88 girls, aged 9 months to 4 years, who were randomized into a multicenter growth hormone intervention trial. Baseline information included a detailed medical history (especially of cardiac and renal anomalies), examination for presence of phenotypic features characteristic of Turner syndrome, length or height (depending on age) expressed as a standard deviation score, and weight standard deviation score. Patients were classified to either the "incidental" (N = 16) or the "traditional" (N = 72) diagnosis group as described above. RESULTS: The incidental group had significantly fewer total phenotypic features of Turner syndrome than the traditional group (3.6 +/- 2.9 vs 6.7 +/- 2.9). When subgrouped by karyotype, the proportion of patients who manifested phenotypic features was greatest in patients with a 45,X nonmosaic karyotype, lowest in the patients with 45,X/46,XX mosaicism, and intermediate in those with "other" karyotypes. Fewer congenital cardiac defects were observed in the incidental group (31%) compared with the traditional group (64%), but there was no difference between the groups in the prevalence of renal defects. Karyotype distribution differed significantly between the traditional and incidental groups: 74% versus 19% had the nonmosaic 45,X karyotype in the traditional group and 7% versus 56% had the mosaic 45,X/46,XX karyotype. CONCLUSIONS: Patients whose Turner syndrome was diagnosed incidentally had significantly fewer phenotypic features and cardiac defects, as well as a greater proportion of mosaic karyotypes, compared with patients whose Turner syndrome was diagnosed clinically. These results support the theory that significant ascertainment bias exists in our understanding Turner syndrome, with important implications for prenatal counseling.

Abnormalities, Multiple↗
PubMed2003

Health supervision for children with Turner syndrome.

This report is designed to assist the pediatrician in caring for the child in whom the diagnosis of Turner syndrome has been confirmed by karyotyping. The report is meant to serve as a supplement to the American Academy of Pediatrics' "Recommendations for Preventive Pediatric Care" and emphasizes the importance of continuity of care and the need to avoid its fragmentation by ensuring a medical home for every girl with Turner syndrome. The pediatrician's first contact with a child with Turner syndrome may occur during infancy or childhood. This report also discusses interactions with expectant parents who have been given the prenatal diagnosis of Turner syndrome and have been referred for advice.

Adolescent↗
PubMed2002

Kyphosis in a Turner syndrome population.

OBJECTIVE: The purpose of this study was to determine the prevalence of kyphosis in a Turner syndrome (TS) population. METHODS: Standing lateral thoracic spine and standing anterior-posterior (A-P) scoliosis radiographs were obtained on all girls with TS between the ages of 5 and 18 years seen in a TS clinic between July 2000 and March 2001. Medical histories were reviewed, and a pediatric orthopedic surgeon evaluated the radiographs of each patient (N = 25). Excessive kyphosis was defined as an A-P curvature >40 degrees, vertebral wedging as any A-P deformity >5 degrees at an individual vertebral body, and scoliosis as a lateral curvature >10 degrees. RESULTS: Fifteen (60%) of 25 patients were found to have abnormal radiographic findings: 10 (40%) of 25 with excessive kyphosis, 10 (40%) of 25 with vertebral wedging, and 5 (20%) of 25 with scoliosis. Forty-eight percent of the girls had both excessive kyphosis and/or vertebral body wedging. Two girls had kyphosis > or =55 degrees, and 5 had scoliosis > or =25 degrees. Girls with excessive kyphosis and/or vertebral body wedging were older (13.6 +/- 3.9 years vs 10.6 +/- 2.8 years). CONCLUSIONS: The prevalence of excessive kyphosis and vertebral body wedging seems to be increased in girls with TS and corresponds with advancing age. Routine radiologic surveillance may facilitate detection of developing deformities so that treatment with a brace can be considered to prevent or slow the process.

Adolescent↗