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J Dotsch, U Meissner and W Rascher

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E Schoof, A Stuppy, F Harig, R Carbon, T Horbach, W Stohr, W Rascher and J Dotsch

OBJECTIVE: Adipose tissue displays depot-specific metabolic properties and a predominant gene expression of leptin in subcutaneous tissue. The aim of the study was to evaluate leptin mRNA expression in various adipose tissues and to relate it to plasma leptin concentrations. Furthermore, developmental changes in leptin gene expression from childhood to adulthood were examined. DESIGN AND METHODS: Thoracic subcutaneous and intrathoracic adipose tissue specimens were obtained in 22 adults (51-81 years) and 23 children (0.1-17 years) undergoing cardiac surgery, and abdominal subcutaneous, omental and mesenterial fat specimens were collected from 21 adults (38-79 years) and 22 children (0.2-17 years) before abdominal surgery. Preoperative plasma leptin concentrations were measured by RIA. Leptin mRNA expression was quantified by TaqMan real-time PCR. RESULTS: In adults, there was no difference between leptin gene expression in subcutaneous and intrathoracic fat, whereas in children leptin mRNA expression was significantly higher in subcutaneous adipose tissue. In omental fat, leptin mRNA levels were significantly lower compared with subcutaneous and mesenterial sites in both children and adults. Adults revealed a significantly higher leptin gene expression in subcutaneous, omental and mesenterial adipose tissues than children. Subcutaneous and omental leptin gene expression are independent factors for plasma leptin concentrations in children and adults. CONCLUSION: Leptin is differentially expressed at different adipose tissue sites, a situation which is even more pronounced in children. There is a developmental increase in leptin mRNA expression in adipose tissue during childhood, reaching maximal capacity in adulthood.

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R Trollmann, E Schoof, E Beinder, D Wenzel, W Rascher and J Dotsch

OBJECTIVE: The aim of the present study was to investigate the role of adrenomedullin (ADM) as a hypoxia-inducible marker of clinically relevant tIssue hypoxia in acute birth asphyxia of term newborn infants. METHODS: For this purpose, ADM mRNA was determined in human placental tIssue of 20 term pregnancies complicated by birth asphyxia (pH and base deficit values, clinical score). In addition, ADM mRNA was measured in leukocytes of the asphyxiated newborn infants during the first 12 h of life (n=12). Controls were available from ten healthy term pregnancies. In vitro, hypoxia-inducible expression of ADM mRNA was evaluated in human choriocarcinoma cells (BeWo) and human leukocytes exposed to hypoxia (1% O(2)) for 1-24 h. mRNA levels were measured by TaqMan real-time PCR. RESULTS: In vitro, ADM mRNA related to porphobilinogen deaminase (PBGD) mRNA levels significantly increased in response to hypoxia within a period of 4 h in leukocytes and 12 h in BeWo cells. In human placental tIssue, significantly higher levels of ADM/PBGD mRNA were present in asphyxiated newborn infants with severe hypoxic-ischemic encephalopathy (HIE) (n=5) compared with patients with mild or no HIE (n=15). Increased levels of ADM/PBGD mRNA levels were found during the first hours of life in leukocytes of neonates with severe HIE compared with controls. CONCLUSIONS: Our results indicate an upregulation of ADM gene expression in human placenta and leukocytes in clinically relevant hypoxic-ischemic birth complications and suggest ADM gene expression as a promising marker for severe complications due to perinatal asphyxia such as HIE.

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W Kiess, M Anil, WF Blum, P Englaro, A Juul, A Attanasio, J Dotsch and W Rascher

The ob protein, termed leptin, is produced by adipocytes and is thought to act as an afferent satiety signal regulating weight through suppressing appetite and stimulating energy expenditure in humans and/or rodents. Insulin has been found to be a potent stimulator of leptin expression in rodents. It is unclear at present whether this insulin action is a direct or an indirect effect. To investigate whether leptin concentrations in children and adolescents with type 1 diabetes (IDDM) were related to metabolic status, body weight, body mass index and insulin treatment, we have measured leptin concentrations in serum from 13 newly diagnosed IDDM patients before the beginning of insulin treatment (8 girls, 5 boys, aged 4.7-17.5 years) and in 134 patients with IDDM during treatment (64 girls, 70 boys, aged 2.6-20.1 years) using a specific radioimmunoassay. The data from patients with diabetes were compared with normative data that were derived from a large cohort of healthy children and adolescents. Serum from children with newly diagnosed diabetes had significantly lower levels of leptin (mean 1.28+/-1.60 ng/ml, range 0.14-6.13 ng/ml) compared with healthy children (n=710) (mean 2.2 ng/ml, range 0.26-14.4ng/ml) and compared with insulin-treated children and adolescents (mean 5.18+/-5.48 ng/ml, range 0.26-29.77 ng/ml) (P<0.0001) even after adjustment for gender and body mass index (BMI). Serum leptin levels in patients with IDDM were significantly correlated with BMI (r=0.42, P<0.0001). Multiple regression analysis showed that age and BMI were significantly correlated with leptin levels, while duration of diabetes, mean HbA1c levels, insulin dose and plasma glucose, triglyceride and cholesterol levels were not. Females had higher serum leptin concentrations than males even when adjusted for BMI (P<0.0001). Surprisingly and most importantly, leptin levels in insulin-treated young adult (Tanner stage 5) patients were significantly higher than values found in the healthy nondiabetic reference population when adjusted for sex, Tanner stage and BMI. These findings suggest that leptin levels in IDDM patients show a similar dependency on adipose tissue and age as in healthy, normal children. The data provide evidence that insulin may be of importance as a regulator of serum leptin levels in vivo not only in rodents but also in humans. It is hypothesized that the elevated BMI-adjusted leptin levels in adolescents with IDDM could indicate either that these patients may be oversubstituted by the intensified insulin therapy that they are receiving or that their body composition and body fat content may differ from that of healthy adolescents in the sense that they have a relative increase in fat mass.

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M Schroth, M Groschl, HG Dorr, WF Blum, W Rascher and J Dotsch

OBJECTIVE: In humans, short term changes of serum leptin lead to alterations in food intake and energy expenditure. The objective of the present study was to relate urine leptin concentrations with the extent of proteinuria in patients with nephrotic syndrome (NS). A second goal was to investigate the impact of potential urinary leptin losses on serum leptin concentrations and body composition. DESIGN AND METHODS: Seventeen patients with proteinuria were compared with twenty patients with remission of NS and ten healthy children. Leptin was measured by radioimmunoassay. RESULTS: Urinary leptin excretion in proteinuric patients was significantly higher than in non-proteinuric patients with and without NS and in healthy controls (2.64+/-0.034 microg/g creatinine, 0.026+/-0.05 microg/g creatinine, and 0.073+/-0.11 microg/g creatinine respectively; P<0.001 and P<0.01 respectively compared with controls). Urine leptin positively correlated with urine IgG concentration (P=0.013, r2=0.36) in the proteinuric group. No difference in serum leptin values could be demonstrated between the three groups. CONCLUSIONS: In summary, our data demonstrate a significant leptin excretion in children with severe proteinuria. Proteinuria, however, does not lead to changes in serum leptin, suggesting that the significant loss of leptin is compensated for by sustained up-regulation of leptin production.

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E Schoof, M Girstl, W Frobenius, M Kirschbaum, R Repp, I Knerr, W Rascher and J Dotsch

BACKGROUND: During human pregnancy, 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) plays an important role in protecting the fetus from high maternal glucocorticoid concentrations by converting cortisol to inactive cortisone. Furthermore, 11beta-HSD2 is indirectly involved in the regulation of the prostaglandin inactivating enzyme 15-hydroxyprostaglandin dehydrogenase (PGDH), because cortisol reduces the gene expression and enzyme activity of PGDH in human placental cells. OBJECTIVE: To examine developmental changes in placental 11beta-HSD2 and PGDH gene expression during the 2nd and 3rd trimesters of human pregnancies. METHODS: In placental tissue taken from 20 healthy women with normal pregnancy and 20 placentas of 17 mothers giving birth to premature babies, 11beta-HSD2 and PGDH mRNA expression was determined using quantitative real-time PCR. RESULTS: Placental mRNA expression of 11beta-HSD2 and PGDH increased significantly with gestational age (r=0.55, P=0.0002 and r=0.42, P=0.007). In addition, there was a significant correlation between the two enzymes (r=0.58, P<0.0001). CONCLUSIONS: In the course of pregnancy there is an increase in 11beta-HSD2 and PGDH mRNA expression in human placental tissue. This adaptation of 11beta-HSD2 prevents increasing maternal cortisol concentrations from transplacental passage and is exerted at the gene level. 11beta-HSD2 up-regulation may also lead to an increase in PGDH mRNA concentrations that, until term, possibly delays myometrial contractions induced by prostaglandins.

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J Kratzsch, I Knerr, A Galler, T Kapellen, K Raile, A Körner, J Thiery, J Dötsch and W Kiess

Objective: Type 1 diabetes mellitus (T1DM) leads to increased serum levels of the soluble leptin receptor (sOB-R) by an as yet unknown cellular mechanism. The aim of our study was to investigate potential metabolic factors that may be associated with the induction of the sOB-R release from its membrane receptor.

Materials and methods: Twenty-five children (aged between 1.5 and 17.0 years) were studied at the onset of T1DM. Blood samples were collected before (n = 25), during the first 18 h (mean ± S.D. 11.1 ± 4.3 h, n = 16) and 92 h (47.5 ± 22.5 h; n = 14) after beginning insulin therapy. Serum sOB-R and leptin levels were determined by in-house immunoassays.

Results: The sOBR-level and the molar sOB-R/leptin ratio were significantly higher before than after starting insulin treatment (P < 0.05). In contrast, leptin levels were significantly lower (P < 0.05) before insulin therapy. The correlation between sOB-R and blood glucose (r = 0.49; P < 0.05), as well as sOB-R with parameters of ketoacidosis, such as pH (r = −0.72), base excess (r = −0.70), and bicarbonate (r = −0.69) (P < 0.0001) at diagnosis of T1DM remained significant during the first 18 h of insulin treatment. Multiple regression analysis revealed that base excess predicted 41.0% (P < 0.001), age 16.4% (P < 0.05), and height SDS 13.9% (P < 0.01) of the sOB-R variance.

Conclusions: Metabolic decompensation in children with new onset T1DM is associated with dramatic changes of the leptin axis; serum levels of sOB-R are elevated and of leptin are reduced. The molar excess of sOB-R over leptin (median 11.3) in this condition may contribute to leptin insensitivity. Upregulation of the soluble leptin receptor appears to be a basic mechanism to compensate for intracellular substrate deficiency and energy-deprivation state.