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- Tallroth, G, et al.
(author)
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Regional cerebral blood flow in normal man during insulin-induced hypoglycemia and in the recovery period following glucose infusion
- 1992
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In: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 41:7, s. 717-721
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Journal article (peer-reviewed)abstract
- The effect of moderate hypoglycemia (p-glucose, 2.0 +/- 0.3 mmol/L; mean +/- SD) on regional cerebral blood flow (rCBF) was studied in a group of 10 healthy, right-handed men (aged 23 to 28 years) using an intravenous xenon 133 single photon emission computed tomography technique (SPECT). After 10 minutes of hypoglycemia, global CBF had increased to 46.3 +/- 9.6 mL/100 g/min compared with the initial normoglycemic flow of 38.6 +/- 6.8 mL/100 g/min (P less than .01). The relative distribution of the rCBF changed significantly (P less than .05, ANOVA) from before to during hypoglycemia. Of the 10 regions analyzed, the highest increments in rCBF during hypoglycemia were found in the frontal (21.5% +/- 15.2%) and parietal (20.6% +/- 14.2%) lobes, and the lowest (10.7% +/- 9.4%) were found in the pons/brainstem regions. The increase in rCBF persisted for 15 minutes after normalization of blood glucose. The persisting high flow after hypoglycemia affected all regions, but a further 10.1% +/- 7.2% increase was observed in the pons/brainstem area (P less than .05). The CBF was significantly higher in the right compared with the left hemisphere (2.8%, 1.2%, and 3.9%, respectively; P less than .05) in all measurements. A decrease in brain volume was found at the final examination, compared with the hypoglycemic state (2.6%; P less than .05). It is concluded that moderate hypoglycemia leads to a marked increase in CBF and in the relative distribution of rCBF, which persists in the immediate period after normalization of the blood glucose level.
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| 2. |
- Mårin, Per, et al.
(author)
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Cortisol secretion in relation to body fat distribution in obese premenopausal women.
- 1992
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In: Metabolism: clinical and experimental. - : Elsevier BV. - 0026-0495. ; 41:8, s. 882-6
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Journal article (peer-reviewed)abstract
- Urinary cortisol output and serum cortisol concentrations were measured in the steady state, under "field" conditions, and during standardized inhibitory and stimulatory tests in premenopausal, obese women, and were analyzed in relation to adipose tissue distribution. Urinary cortisol output was increased under field conditions in women with an elevated waist to hip circumference ratio (WHR) and, in particular, in women with a large abdominal sagittal diameter, indicating visceral fat accumulation. However, dexamethasone inhibition of cortisol secretion was normal. Stimulation with corticotropin analogue and with physical (cold-pressor test) or mental (color-word or mathematic) stress tests also showed elevated responses of serum cortisol, but not of prolactin or growth hormone concentrations. It is suggested that women with visceral fat accumulation have elevated cortisol secretion due to an increased sensitivity along the hypothalamic-pituitary-adrenal axis, and that this may be causing their abnormal fat depot distribution.
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| 3. |
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| 4. |
- Mårin, P, et al.
(author)
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The morphology and metabolism of intraabdominal adipose tissue in men.
- 1992
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In: Metabolism: clinical and experimental. - 0026-0495. ; 41:11, s. 1242-8
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Journal article (peer-reviewed)abstract
- Mass, morphology, and metabolism of total adipose tissue and its subcutaneous, visceral, and retroperitoneal subcompartments were examined in 16 men with a wide variation of total body fat. Computerized tomography (CT) scans showed that the intraabdominal fat mass comprised approximately 20% of total fat mass. Visceral and retroperitoneal fat masses were approximately 80% and 20% of total intraabdominal fat mass, respectively. Enlargement of intraabdominal fat depots was due to a parallel adipocyte enlargement only. Direct significant correlations were found between these adipose tissue masses and blood glucose and plasma insulin levels, blood pressure, and liver function tests, while glucose disposal rate during euglycemic glucose clamp measurements at submaximal insulin concentrations (GDR), plasma testosterone, and sex hormone-binding globulin concentrations correlated negatively. The correlations for glucose, insulin, and GDR were strongest with visceral fat mass. Adipose tissue lipid uptake, measured after oral administration of labeled oleic acid in triglyceride, was approximately 50% higher in omental than in subcutaneous adipose tissues. Adipocytes from omental fat also showed a higher lipolytic sensitivity and responsiveness to catecholamines. Furthermore, these adipocytes were less sensitive to the antilipolytic effects of insulin. Both lipid uptake and lipolytic sensitivity and responsiveness showed strong correlations (r = 0.8 to 0.9) to blood glucose and plasma insulin concentrations and also to the GDR (negative), while no such correlations were found with lipid uptake in subcutaneous or retroperitoneal abdominal adipose tissues. Taken together, these results suggest a higher turnover of lipids in visceral than in the other fat depots, which is closely correlated to systemic insulin resistance and glucose metabolism in men.
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