Antilipolysis as a tool in the study of clinical and experimental diabetes. Lecture for the 1968 Minkowski Award

Correction of insulin sensitivity and glucose disposal after pancreatic islet transplantation: preliminary results

AIMS

Pancreatic islet transplantation (PIT) represents a potential curative treatment for patients with type 1 diabetes, but only 10-15% of patients remain insulin independent 5 years post-transplant. It is not known whether intrinsic insulin resistance exacerbated by immunosuppression plays a pivotal role in low graft survival. The study objective was to understand the changes in insulin resistance, glucose effectiveness (S(g)) and free fatty acid dynamics (FFAd) before and after PIT.

METHODS

Insulin sensitivity index (S(i)), S(g) and FFAd were measured before and after PIT in 10 lean patients, 8 of whom reached insulin independence. Modified Bergman minimal model of frequently sampled intravenous glucose tolerance tests were performed pretransplant and at 12 months post-transplant. Nine non-diabetic control (NDC) subjects matched by age, gender and BMI were used.

RESULTS

Pretransplant S(i) and S(g) were 3.5 ± 0.8 × 10(-5)/min/(pmol/l) and 0.74 ± 0.24 × 10(-2)/min, respectively. S(i) was significantly lower than matched NDCs [10.8 ± 0.6 × 10(-5)/min/(pmol/l), p < 0.004]; S(g) did not reach statistical significance (1.27 ± 0.22 × 10(-2)/min, p = 0.25). Compared to pretransplant values, mean post-transplant S(i) and S(g) were 9.6 ± 1.3 × 10(-5)/min/(pmol/l)and 1.28 ± 0.22 ×10(-2)/min, respectively, indicating significant improvement for S(i) but not S(g) (p = 0.008 and p = 0.06). Twelve-month post-PIT compared to NDC values were not significantly different (p = 0.58 and 0.97, respectively). In addition, fractional disposal rate for FFA which directly depends on the endogenous insulin release (10-20 min) nearly normalized after PIT (p = 0.06).

CONCLUSION

These preliminary findings demonstrate that PIT can restore glucose disposal and insulin sensitivity and partially correct glucose effectiveness and FFAd.

Nicotinic acid: the broad-spectrum lipid drug. A 50th anniversary review

Nicotinic acid has, like the Roman God Janus, two faces. One is the vitamin. The other is the broad-spectrum lipid drug. The Canadian pathologist Rudolf Altschul discovered 50 years ago that nicotinic acid in gram doses lowered plasma levels of cholesterol. From the point of view of treatment of the dyslipidaemias that are risk factors for clinical atherosclerosis nicotinic acid is a miracle drug. It lowers the levels of all atherogenic lipoproteins--VLDL and LDL with subclasses as well as Lp(a)--and in addition it raises more than any other drug the levels of the protective HDL lipoproteins. Trials have shown that treatment with nicotinic acid reduces progression of atherosclerosis, and clinical events and mortality from coronary heart disease. The new combination treatment with statin-lowering LDL and nicotinic acid-raising HDL is reviewed. A basic effect of nicotinic acid is the inhibition of fat-mobilizing lipolysis in adipose tissue leading to a lowering of plasma free fatty acids, which has many metabolic implications which are reviewed. The very recent discovery of a nicotinic acid receptor and the finding that the drug stimulates the expression of the ABCA 1 membrane cholesterol transporter have paved the way for exciting and promising new 50 years in the history of nicotinic acid.

Theoretical aspects of weight loss in patients with cancer. Possible importance of pyruvate dehydrogenase

In the analysis of weight loss in cancer patients, consideration must be given to decreased caloric intake, increased caloric expenditure and abnormal losses of calories. When these factors do not adequately explain the degree of weight loss, this may be due to a specific loss of lean body mass, as the caloric density of muscle is much less than that of fat. The key enzyme for the protection of lean body mass in hypocaloric states is pyruvate dehydrogenase (PDH). During fasting, fast oxidation in host tissues leads to inactivation of PDH, preventing irreversible loss of pyruvate precursors which would have to be replaced by protein breakdown. A tumor in which PDH activity remains high in the fasting state would cause loss of lean body mass in the host. This report suggests that this phenomenon may be important in certain patients with cancer cachexia.

Acute reversal of experimental diabetic ketoacidosis in the rat with (+)-decanoylcarnitine

The effect of (+)-decanoylcarnitine, a potent inhibitor of long-chain acylcarnitine transferase, was tested for its ability to inhibit hepatic ketogenesis both in the isolated perfused liver and in vivo in severely ketotic alloxan diabetic rats. In vitro the inhibitor caused an almost complete block in ketone body production. In vivo (+)-decanoylcarnitine caused a rapid reversal of ketosis under conditions where large doses of insulin had little effect. A combination of the two agents produced an even more striking fall in plasma ketone levels.While (+)-decanoylcarnitine alone had no effect on plasma glucose levels it enhanced the hypoglycemic effect of insulin in anesthetized animals. Loss of this effect was noted in nonanesthetized animals, possibly as a result of increased muscle activity. Studies in the isolated perfused liver indicated that the blockade of fatty acid oxidation and ketogenesis produced by (+)-decanoylcarnitine was rapidly reversible upon removal of the inhibitor.