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Biomedical subjects

Dennis M Styne

Publications and source records attributed to Dennis M Styne.

9 recordsLinked to original sources
PubMed2005

Administration of Lispro insulin with meals improves glycemic control, increases circulating leptin, and suppresses ghrelin, compared with regular/NPH insulin in female patients with type 1 diabetes.

CONTEXT: Overweight and obesity are overrepresented in adolescents with type 1 diabetes mellitus (T1DM). Exogenous insulin administration often poorly reproduces normal insulin patterns and may less effectively regulate leptin and ghrelin, two hormones involved in the control of appetite and adiposity. OBJECTIVE: The objective of the study was to determine whether insulin regimens that better replicate normal insulin patterns and augment postprandial nutrient disposal may help normalize leptin and ghrelin and improve body weight regulation. DESIGN, SETTING, AND PARTICIPANTS: Ten young women with T1DM were studied in this 2-wk prospective, balanced crossover-design study at the University of California, Davis. INTERVENTION: Participants received either a single injection of regular + NPH insulin (R+N) or two mealtime injections of Lispro insulin in randomized order on 2 separate days. Meal composition and total insulin administered were the same on both treatment days. MAIN OUTCOME MEASURES: Plasma glucose, insulin, leptin, and ghrelin concentrations were monitored over the 10-h study period. RESULTS: Lispro produced two distinct mealtime peaks of insulin, compared with one prolonged rise with R+N. Lispro reduced postprandial hyperglycemia and total glucose area under the curve. Leptin increased more on the Lispro (2.7 +/- 0.7 vs. 0.7 +/- 0.5 ng/ml, P = 0.02). Ghrelin was more suppressed after lunch with Lispro (P = 0.004). CONCLUSIONS: Injection of Lispro insulin with meals produces more physiological insulin patterns, better glucose control, and improved leptin and ghrelin regulation than R+N. More closely mimicking normal insulin, leptin, and ghrelin responses to meals with fast-acting insulin may have implications for body weight regulation in T1DM.

Adolescent↗
PubMed2005

Body composition and water compartment measurements in boys with Duchenne muscular dystrophy.

OBJECTIVE: Duchenne muscular dystrophy (DMD) patients have a lower percentage of total body water and higher extracellular water to intracellular water (ECW/ICW) ratio compared with normal subjects. However, it is not known whether this is due to increased fat mass or a decreased amount of ICW in muscle cells in DMD patients. The purpose of this study was to (1) determine the effect of increased fat mass and decreased lean mass on the ECW to ICW ratio in DMD patients and to (2) determine the validity of multifrequency bioelectrical impedance analysis (MFBIA) in assessing body composition in DMD patients. DESIGN: This study has a quasi-experimental, comparative design using nonequivalent groups. A total of 46 boys ranging from 6 to 13 yrs of age participated in this study. There were 12 nonobese able-bodied controls, 19 obese able-bodied children (obese), and 15 boys with DMD. Body composition was measured by dual-energy x-ray absorptiometry (DEXA). Body composition and body water compartment analysis were assessed by MFBIA. All measurements obtained using MFBIA were compared with those obtained using DEXA for validation. RESULTS: Both MFBIA and DEXA measures were strongly correlated in control (r = 0.99), obese (r = 0.92), and DMD subjects (r = 0.95). However, lean tissue mass measured by DEXA in the DMD subjects was only slightly higher (19.2 +/- 1.1 vs. 18.2 +/- 1.2, P < 0.02) than as measured by MFBIA. Mean percentage of body fat measured by DEXA in the DMD subjects (30.4 +/- 3.1%) was significantly lower than as measured by MFBIA (38.7 +/- 2.2%). The mean percentage of body fat measured by DEXA in the control group (23.2 +/- 1.8%) was significantly (P < 0.001) lower than as measured by MFBIA (28.6 +/- 1.6%). The mean percentage of body fat measured by DEXA in obese able-bodied controls (40.8 +/- 0.9%) was not significantly different from that measured by MFBIA (40.4 +/- 1.5%). Compared with the obese and control subjects, DMD subjects showed reduced ICW and ECW, with an increased ECW/ICW ratio, as expected. However, the percentage of fat for the DMD group was not different from the obese group. CONCLUSIONS: DMD patients have elevated ECW/ICW ratios compared with obese subjects and nonobese controls. However, obese subjects and nonobese controls had similar ECW/ICW ratios, despite the increased fat tissue mass in obese subjects. This suggests that the elevated ECW/ICW ratios in DMD subjects are not due to increased fat mass but rather some other mechanism, likely impaired cellular homeostasis due to muscle membrane instability. Although MFBIA slightly underestimates lean tissue mass in boys with DMD, it has a potential role as an inexpensive and easy to use measurement tool to measure changes in muscle mass in the clinical setting.

Absorptiometry, Photon↗
PubMed2004

Puberty, obesity and ethnicity.

Lay and medical sources state that children enter puberty earlier now than in past decades. Although it is clear that puberty and menarche currently begin at younger ages than they did in past centuries, a comparison of the onset of puberty during the few past decades is more difficult to interpret. African-American girls do start puberty earlier and menarche is earlier than in White girls, and the gap between the two has widened during the past 20 years. This change between ethnic groups might be due to an increasing difference in body mass index (BMI) values. Greater BMI values are associated with pubertal onset or menarche; thus, if BMI continues to increase in childhood, earlier puberty might well be found in the general population in the future. In the absence of accurate data from the past or definitive studies at present, however, it cannot be stated with assurance that puberty today starts significantly earlier than it did in the past 4-5 decades across the whole population.

Adolescent↗
PubMed2004

Benefits of an insulin dosage calculation device for adolescents with type 1 diabetes mellitus.

OBJECTIVE: Multiple daily injection insulin regimens (MDI) and continuous subcutaneous insulin infusion (CSII) allow adolescents with type 1 diabetes mellitus (DM) meal flexibility, and may improve metabolic control. The insulin dosage calculations, however, involve ratios of insulin to carbohydrate and corrections for high blood glucose values, and are labor-intensive and prone to error. We evaluated the impact of an insulin dosage calculation device (IDC) on metabolic control, treatment satisfaction, regimen adherence and quality of life in adolescents using MDI or CSII. RESEARCH DESIGN AND METHODS: We conducted a randomized control trial using the IDC in 83 adolescents on MDI or CSII. At enrollment, patients received training on dosage calculation using either the IDC or conventional methods, and performed sample calculations. At enrollment, 6 months and 12 months, we recorded HbA1c and frequency of hypoglycemia, and patients completed questionnaires assessing treatment satisfaction, regimen adherence and quality of life. After 6 months, patients in the control group were also given the IDC. RESULTS: We observed a higher frequency of errors with conventional calculations (53-67% incorrect calculations) than with the IDC (25-32% incorrect). At 6 months, there was a trend toward improved HbA1c in the IDC group overall (9.3 vs 8.9, p = 0.07) and a significant improvement in the subset (42%) who used the IDC consistently (9.7 vs 8.8, p = 0.03). There was no change in HbA1c in the control group during this interval (9.0 vs 8.9, p = 0.90). During months 6-12, when both groups were combined, there was a significant increase in HbA1c in patients using the IDC inconsistently or not at all (8.9 vs 9.4, p = 0.005), but no change in HbA1c in those using the IDC consistently (9.1 vs 8.9, p = 0.57). Treatment satisfaction, adherence and quality of life improved throughout the study in both groups. CONCLUSIONS: Errors in calculation of insulin dosage by adolescents occur frequently. Consistent use of an insulin dosage calculation device may help to improve metabolic control in adolescents using MDI or CSII.

Adolescent↗
PubMed2003

The regulation of pubertal growth.

To understand the regulation of pubertal growth, it is important to understand the present concept of the control of the onset of puberty, the change in secretion of sex steroids during puberty, and the effects of these various factors upon the production and action of growth hormone (GH) and insulin-like growth factor (IGF). Nutrition plays a major role in this process because states of aberrant nutrition severely affect pubertal growth. In this article, all of these concepts will be discussed, including the effect of these factors upon bone growth during the increase in stature accomplished during puberty.

Adolescent↗
PubMed2003

A practical approach to the diagnosis of growth hormone (GH) deficiency in patients transitioning to adulthood using GH stimulation testing.

To establish the diagnosis of adult growth hormone deficiency (GHD), GH-deficient children transitioning to adulthood are evaluated by two separate stimuli 2 or more weeks after ceasing GH therapy. While 20-88% of children diagnosed with idiopathic GHD retest with normal values, those with proven genetic defects in GH production/secretion/bioactivity and patients with panhypopituitarism consistently test deficient. The US Food and Drug Administration (FDA) defines GHD in adults by stimulated peak serum GH concentrations <5 ng/ml if measured by polyclonal radioimmunoassays (RIA) or lower if measured by monoclonal assays. Some investigators define severe GHD by a peak GH concentration <3 ng/ml. Adult responses to arginine and glucagon testing are similar to the responses to insulin tolerance testing; clonidine, pyridostigmine, and galanin cause lesser peaks of GH. Growth hormone-releasing hormone (GHRH) combined with arginine, GH releasing peptide-6 (GHRP-6), or hexarelin leads to higher peak responses than GHRH alone. Thus the choice of testing methods impacts the diagnosis of GHD in transition patients.

Adolescent↗