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Biomedical subjects

I Choe

Publications and source records attributed to I Choe.

6 recordsLinked to original sources
PubMed2001

Leptin interacts with heart rate but not sympathetic nerve traffic in healthy male subjects.

OBJECTIVE: Administration of leptin to animals increases sympathetic nerve activity and heart rate. We therefore tested the hypothesis that plasma leptin is linked independently to muscle sympathetic nerve activity (MSNA) and heart rate in healthy humans. METHODS: We measured plasma leptin, plasma insulin, body mass index (BMI), percent body fat, waist: hip ratio, MSNA, heart rate and blood pressure in 88 healthy individuals (50 men and 38 women). RESULTS: In men, plasma leptin concentration correlated significantly with BMI (r = 0.75, P < 0.001), percent body fat (r = 0.70, P< 0.001), waist: hip ratio (r = 0.69, P < 0.001), insulin (r = 0.37, P = 0.009), and age (r = 0.38, P = 0.006). Only BMI and waist: hip ratio were linked independently to plasma leptin concentration (r = 0.78, P < 0.001). Plasma leptin concentrations also correlated with heart rate (r = 0.39, P = 0.006) and mean arterial pressure (MAP; r = 0.38, P = 0.007), but not with MSNA (r = 0.17, P = 0.24). After adjustment for BMI and waist: hip ratio, plasma leptin concentration correlated significantly only with heart rate (r = 0.29, P = 0.04), and not with MAP (r = 0.21, P = 0.14). Individuals were divided into high-leptin and low-leptin subgroups on the basis of plasma leptin concentrations adjusted for BMI and waist: hip ratio. Those with high leptin concentrations had significantly faster heart rates than those with low leptin. MAP and MSNA were similar in both subgroups. No relationship between leptin and either heart rate or MSNA was evident in women. CONCLUSIONS: In normal men, heart rate, but not MSNA, is linked to plasma leptin concentration. This sex-specific relationship between heart rate and plasma leptin is independent of plasma insulin, BMI, waist:hip ratio and percentage body fat.

Adult↗
PubMed2000

Transsphenoidal supradiaphragmatic intradural approach: technical note.

Presellar extension of the bone window combined with removal of the sellar floor results in the transsphenoidal supradiaphragmatic intradural approach. One tuberculum sella meningioma and another suprasellar Rathke's cleft cyst confined to the pituitary stalk were removed via this approach. The presellar extension of the bone window was performed with the sublabial transseptal transsphenoidal technique. Furthermore, the dissection of the anterior intercavernous sinus, diaphragma sella, and arachnoid trabecula has allowed a wide surgical field of pre- and suprasellar areas and facilitates safe removal of lesions without significant surgical complications in selected cases.

Adult↗
PubMed2000

Increases in leptin levels, sympathetic drive, and weight gain in obstructive sleep apnea.

Patients with obstructive sleep apnea (OSA) are frequently obese and are predisposed to weight gain. They also have heightened sympathetic drive. We reasoned that noradrenergic activation of beta(3)-receptors on adipocytes would inhibit leptin production, predisposing to obesity in sleep apnea. We therefore tested the hypothesis that obesity and predisposition to weight gain in OSA are associated with low levels of plasma leptin. We prospectively studied 32 male patients (43 +/- 2 yr) with OSA who were newly diagnosed and never treated and who were free of any other diseases. Control measurements were obtained from 32 similarly obese closely matched male subjects (38 +/- 2 yr). Leptin levels were 13.7 +/- 1.3 and 9.2 +/- 1.2 ng/ml in patients with OSA and controls, respectively (P = 0.02). Weight gain over the year before diagnosis was 5.2 +/- 1.7 and 0.5 +/- 0.9 kg in sleep apnea patients and similarly obese control subjects, respectively (P = 0.04). Muscle sympathetic activity was 46 +/- 4 and 30 +/- 4 bursts/min in patients with OSA (n = 16) and control subjects (n = 18), respectively (P = 0.01). Plasma leptin levels are elevated in newly diagnosed otherwise healthy patients with untreated sleep apnea beyond the levels seen in similarly obese control subjects without sleep apnea. Higher leptin levels in OSA, independent of body fat content, suggest that OSA is associated with resistance to the weight-reducing effects of leptin.

Adult↗
PubMed1999

Heritability of plasma leptin levels: a twin study.

OBJECTIVE: To examine the influence of genetic factors on plasma leptin levels. SUBJECTS AND METHODS: We measured plasma leptin levels, body mass index and body fat distribution in healthy young female monozygotic (n = 19) and dizygotic (n = 14) twins. The twin zygosity was verified by determination of short tandem repeat and amplified fragment length polymorphism systems. The genetic analysis included analysis of variance-based and maximum likelihood-based methods. RESULTS: Plasma leptin levels were correlated significantly with body mass index (r = 0.59, P < 0.001), waist circumference (r = 0.54, P < 0.001) and hip circumference (r = 0.63, P < 0.001), but not with age (r = -0.17) or the waist:hip ratio (r = 0.02). The heritability estimates derived from intraclass correlations were significant for body mass index (P = 0.001), waist circumference (P = 0.004), hip circumference (P = 0.01) and plasma leptin levels (P = 0.005), but not for the waist:hip ratio (P = 0.22). In the maximum likelihood-based path analysis, heritability was estimated at 79% for body mass index and at 73% for plasma leptin levels. After adjustment for body mass index, the heritability estimate for leptin levels from the model-fitting approach was 55%. CONCLUSIONS: Genetic factors are major determinants of plasma leptin levels in humans and may account for as much as half of the variance in leptin levels.

Adipose Tissue↗
PubMed1987

A hepatic fibrogenic factor stimulates the synthesis of types I, III, and V procollagens in cultured cells.

A hepatic fibrogenic factor (HFF) isolated from fibrotic rat livers has previously been shown to stimulate the transcription of type I procollagen genes in cultured fibroblasts (Raghow, R., Gossage, D., Seyer, J. M., and Kang, A.H. (1984) J. Biol. Chem. 259, 12718-12723). To test if the expression of other collagen genes was similarly affected by the fibrogenic factor, we measured the rates of types I, III, and V procollagen synthesis in two different cell lines after treatment with HFF. The effect of fibrogenic factor on types I and III procollagens was tested in rat fibroblasts, while a human rhabdomyosarcoma cell line was used to evaluate the effect of HFF on type V procollagen synthesis. Incubation with rat fibroblasts resulted in a 3-4-fold stimulation of the synthesis of both types I and III procollagens in a time-dependent manner. The stimulated rates of types I and III procollagen synthesis accompanied an increase in the steady-state levels of their corresponding mRNAs. When A204 cells, which are derived from a rhabdomyosarcoma and exclusively synthesize type V procollagen, were incubated with the fibrogenic factor, a 3-4-fold stimulation of the synthesis of both pro-alpha 1(V) and pro-alpha 2(V) chains was seen. Using a cDNA probe for pro-alpha 2(V), we also observed that there was a 2-3-fold increase in the steady-state level of pro-alpha 2(V) mRNA in A204 cells after treatment with the fibrogenic factor. In both rat fibroblasts and A204 cells the steady-state levels of beta-actin mRNA were minimally affected by fibrogenic factor, suggesting that the procollagen genes were preferentially affected. Since types I, III, and V collagens are present in the normal liver and accumulate aberrantly in the fibrotic liver, we suggest that fibrogenic factor may play an important role in determining the altered collagen composition of the fibrotic liver. Based on these data, we also speculate that the regulation of the biosynthesis of a variety of procollagens in diverse cell types by HFF possibly occurs by a common mechanism.

Animals↗