Inhibition of glucose transport in fat cells and activation of lipolysis by glucocorticoids

Rapid progression of spinal epidural lipomatosis after percutaneous endoscopic spine surgery mimicking disc herniation

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Spinal epidural lipomatosis can occur and progress rapidly after endoscopic spine surgery.

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As in our case, focally progressed SEL anterior to the dural sac could be misdiagnosed for disc herniation.

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SEL should be recognized as a rare complication of endoscopic spine surgery.

Introduction

Spinal epidural lipomatosis (SEL) is well known but uncommon complication of endoscopic spine surgery. Here, we present a case of SEL that progressed focally and rapidly after endoscopic spinal surgery.

Presentation of case

A 67-year-old man presented with back and Lt. leg radiating pain. MRI of the lumbar spine demonstrated severe foraminal stenosis at Lt. L4/5/S1. He underwent endoscopic posterior foraminotomy at Lt. L4/5/S1. After surgery, his leg pain disappeared. A month after surgery, the patient developed Lt. leg pain again. MR images showed focally progressed epidural fat posterior to the L5 body. After removal of lipomatosis via endoscopic posterior decompression at L3/4/5, his symptoms improved.

Discussion

Mostly, the epidural fat accumulates insidiously, and distributes widely across several levels. And the increased accumulation of fat is predominantly posterior and posterolateral within the spinal canal. As in this case, focally progressed SEL anterior to the dural sac is rare. And focally progressed SEL can be misdiagnosed for disc herniation.

Conclusion

SEL should be recognized as a rare complication of endoscopic spine surgery.

Using blubber explants to investigate adipose function in grey seals: glycolytic, lipolytic and gene expression responses to glucose and hydrocortisone

Adipose tissue is fundamental to energy balance, which underpins fitness and survival. Knowledge of adipose regulation in animals that undergo rapid fat deposition and mobilisation aids understanding of their energetic responses to rapid environmental change. Tissue explants can be used to investigate adipose regulation in wildlife species with large fat reserves, when opportunities for organismal experimental work are limited. We investigated glucose removal, lactate, glycerol and NEFA accumulation in media, and metabolic gene expression in blubber explants from wild grey seals. Glycolysis was higher in explants incubated in 25 mM glucose (HG) for 24 h compared to controls (C: 5.5 mM glucose). Adipose-derived lactate likely contributes to high endogenous glucose production in seals. Lipolysis was not stimulated by HG or high hydrocortisone (HC: 500 nM hydrocortisone) and was lower in heavier animals. HC caused NEFA accumulation in media to decrease by ~30% relative to C in females, indicative of increased lipogenesis. Lipolysis was higher in males than females in C and HG conditions. Lower relative abundance of 11-β-hydroxysteroid dehydrogenase 1 mRNA in HG explants suggests glucose involvement in blubber cortisol sensitivity. Our findings can help predict energy balance responses to stress and nutritional state in seals, and highlight the use of explants to study fat tissue function in wildlife.

A case of diabetic ketoacidosis associated with Guillain-Barré syndrome

A 64-year-old woman was referred to our center presenting with thirst, malaise, and pain in both legs which occurred one week before admission. She was revealed to have hyperglycemia and diabetic ketoacidosis (DKA). After therapy for diabetic ketoacidosis was started, her blood glucose levels were improved, but urinary ketone body excretion persisted. Laboratory examination indicated a significant impairment of insulin secretion, although anti-GAD and anti-IA-2 antibody were not detected. After admission, she complained about weakness of lower extremities, which spread to her upper extremities. The diagnosis of Guillain-Barré syndrome (GBS) was made based on the nerve conduction study and cerebrospinal fluid analysis. The intravenous immunoglobulin therapy was started, and her muscle weakness showed gradual improvement. Although the possibility that GBS was casually accompanied with DKA could not be completely excluded, we considered that DKA triggered the development of GBS in this case. Although GBS is a rare condition, the present case suggests that GBS should be included in the differential diagnosis of DKA with its atypical course.

The impact of different glucocorticoid replacement schedules on bone turnover and insulin sensitivity in patients with adrenal insufficiency

OBJECTIVE

Optimization of physiological replacement of glucocorticoid in patients with adrenal insufficiency is controversial. The present study was undertaken to compare the relative impact of three different regimes of glucocorticoid replacement in patients with adrenal insufficiency on parameters of bone turnover and insulin sensitivity.

PATIENTS

Six female and three male patients with adrenal insufficiency and 17 female and 14 male control subjects participated.

DESIGN

This was an open study conducted in a university teaching hospital. Schedule 1 (S1) consisted of hydrocortisone 10 mg with breakfast and 5 mg with lunch. S2 was similar to S1 with the addition of 5 mg hydrocortisone with the evening meal. S3 utilized dexamethasone 0.1 mg/15 kg body weight given per day with breakfast only. Each schedule was given for at least 4 weeks in random sequence to nine patients with adrenal insufficiency.

METHODS

Blood was obtained at 0900 h (fasting) and at 1300 h for measurement of the ionized calcium (Cai), PTH, 25-hydroxyvitamin D and the bone formation markers intact osteocalcin and amino-terminal propeptide of type 1 procollagen (PINP). Timed urine collections were made under standardized conditions, that is while fasting between 0700 and 0900 h (basal) and between 0900 and 1300 h for measurement of the bone resorption markers, free deoxypyridinoline (FDPD) and cross-linked N-telopeptide of type 1 collagen (NTX). Blood was drawn for measurement of fasting plasma glucose and serum insulin levels. Insulin (0.075 IU/kg) was administered i.v. while the patient was fasting prior to the first glucocorticoid replacement dose on each study day. Plasma glucose was measured before and 3, 6, 9, 12 and 15 min after insulin administration to calculate the glucose disappearance rate (Kitt). Insulin resistance (IR) and beta-cell function were estimated using the homeostasis model assessment (HOMA). Glucocorticoid dosage was given according to the various schedules at approximately 0930 h.

RESULTS

During all three treatment schedules the serum Cai level was significantly lower than that seen in control subjects. PTH levels in patients taking the three replacement schedules and in normal subjects were similar. Serum 25-hydroxyvitamin D levels were not suppressed in the patients during any of the three treatment schedules. The bone resorption marker urinary FDPD under basal conditions was significantly lower during S3 (dexamethasone) than during either hydrocortisone schedules, S1 or S2. Urinary NTX values were not significantly different in the three study groups. The bone formation markers intact osteocalcin and PINP were similar in the three replacement schedules. The indices of IR and beta-cell function tended to be higher during treatment with dexamethasone than with S1 or S2 but did not achieve statistical significance.

CONCLUSIONS

These data indicate that all three replacement schedules were associated with low serum ionized calcium levels without evidence of a compensatory increase in PTH levels. These findings are consistent with direct or indirect suppression of the bone remodelling cycle and suppression of PTH levels. Bone turnover in patients with adrenal insufficiency treated with schedule 3, dexamethasone, was associated with lower bone turnover than patients treated with hydrocortisone schedules 1 or 2. While indices of insulin sensitivity measured during schedules 1, 2 and 3 did not achieve statistical significance, there was an obvious trend for greater insulin resistance to occur with schedules 3 using dexamethasone.

Symptomatic spinal epidural lipomatosis after local epidural corticosteroid injections: case report

OBJECTIVE AND IMPORTANCE

Spinal epidural lipomatosis, which causes symptomatic compression of neural elements, is a well known but uncommon complication of Cushing's syndrome. Spinal epidural lipomatosis has been reported frequently in association with chronic systemic corticosteroid therapy, but thus far only one case has been attributed to local epidural corticosteroid injections.

CLINICAL PRESENTATION

We report another case of symptomatic spinal epidural lipomatosis after epidural corticosteroid injections. This is the first such case documented by magnetic resonance imaging and confirmed with surgical exploration.

INTERVENTION

The patient's symptoms of neurogenic claudication resolved after lumbar laminectomy in the region of previous corticosteroid injections and the removal of epidural fat, which was compressing the thecal sac.

CONCLUSION

This case should alert clinicians that epidural lipomatosis, which causes symptomatic thecal sac compression, is a possible complication, not only of systemic glucocorticoid therapy, but also of local epidural corticosteroid injections.

The metabolic and nutritional effects of injury and sepsis

The existence of a co-ordinated response to stress of a variety of causes has clearly been established. Basically, this consists of an elevation in energy expenditure and an increased breakdown of skeletal muscle protein. In addition, glucose level in the plasma increases as a result of increased synthesis and decreased uptake of glucose into cells. Release of fatty acid into the plasma is also increased, and an elevation in the proportion of energy derived from oxidation of fatty acids is observed. This response is qualitatively very different from that seen in simple starvation, where a progressive reduction in energy expenditure and a reduction in the synthesis of glucose allows fat to become the major energy-producing substrate and also allows sparing of body protein stores. The mechanisms responsible for this altered pattern of metabolism are probably primarily hormonal in nature, with adrenaline, cortisol and glucagon being the major catabolic stimulants. Some evidence exists, however, for alteration in intracellular pathway metabolism. Within the past decade a new class of mediators of the stress response, the cytokines, has been recognized. These substances are protein products of circulating monocytes and the way in which they integrate into the control of the stress response has not been completely elucidated. At present there is evidence that they can stimulate production of catabolic hormones, and also they may well have direct effects in enhancing protein catabolism in muscle. At present the main method for modification of the stress response remains the provision of energy and amino acid, either intravenously or enterally. In the present state of our knowledge, 30-40 kcal kg-1 day-1 would appear to be adequate for most patients, with half provided as fat. Amino acids 3 g kg-1 day-1 will provide adequate nitrogen. It must be said, however, that the most effective method of modifying the stress response is removal of the source of stress by surgery, antibiotics or other primary therapy.

Epidural hibernoma as a complication of corticosteroid treatment. Case report

Centripetal fat deposition is a well-recognized consequence of excessive use of corticosteroids, either endogenous or exogenous. Recently, several patients receiving large doses of corticosteroids have suffered compressive myelopathies due to excessive epidural fat collections, labeled "epidural lipomatosis." Two of these have been children, and a third child is reported here. This child was receiving chronic steroids for juvenile rheumatoid arthritis when he presented with such a myelopathy, which was confirmed by metrizamide computerized tomography myelography as well as by surgical exploration. Histological examination revealed that the epidural tissue was a brown-fat tumor or "hibernoma." An epidural hibernoma has not been described previously. The histological and endocrine features of fat in Cushing's syndrome are discussed, and the literature concerning hibernoma and epidural lipomatosis is reviewed.

Interactions of insulin and dexamethasone in the control of pyruvate kinase activity and glucose metabolism in sheep adipose tissue

1. The Vmax. activity of pyruvate kinase of sheep adipose tissue increased during tissue culture up to 48 h; the increase was blocked by actinomycin D (an inhibitor of transcription) and was promoted by insulin and antagonized by dexamethasone. 2. In contrast with their effects on pyruvate kinase, insulin and dexamethasone acted synergistically to increase the activity of glucose-6-phosphate dehydrogenase of sheep adipose tissue maintained in culture. 3. Insulin stimulated, whereas dexamethasone inhibited, glucose utilization by sheep adipose tissue maintained in culture; the two agents were mutually antagonistic, and their effects were prevented by actinomycin D. 4. Antimycin A (an inhibitor of the electron-transport chain) stimulated glucose uptake and lactate output by sheep adipose tissue in the presence of dexamethasone and insulin, suggesting that the effects of dexamethasone on glucose utilization by sheep adipose tissue were not due to an inhibition of glucose transport. 5. Comparison of these findings with previous studies on the endocrine control of hepatic pyruvate kinase shows that there are major differences in the control of these Vmax. activities in liver and adipose tissue. 6. Although glucocorticoid hormones inhibit glucose utilization themselves and can antagonize the stimulatory effects of insulin on glucose utilization in adipose tissue from both sheep and rats, there appear to be major differences in the sites of action of these hormones in the two species.