Visfatin serum level and expression in subcutaneous and visceral adipose tissue in prepubertal boys

BACKGROUND

The biological role of visfatin in humans, especially in eutrophic and healthy children, is not understood yet, except for its link to obesity-related disorders in adolescents and adults.

OBJECTIVES

To determine the physiological values of serum visfatin concentrations, and visfatin mRNA expression in subcutaneous (SAT) and visceral adipose tissue (VAT), and to correlate them with anthropometric/metabolic data in prepubertal healthy boys.

METHODS

The study included 59 healthy boys, age 1-10 years, hospitalized for elective surgery, divided according to age into group I (1-3 years old), group II (3-7 years old) and group III (7-10 years old). Anthropometric and biochemical measurements, and the visfatin serum and mRNA level in SAT and VAT were determined in all patients.

RESULTS

Visfatin mRNA expression was higher in SAT compared with VAT in all three studied groups. Highest visfatin mRNA was found in SAT of group III compared with group II (P = 0.030). VAT visfatin mRNA expression negatively correlates with body weight (P = 0.039), waist circumference (P = 0.027) and morning glucose level (P = 0.007).

CONCLUSION

Lack of changes in serum visfatin level despite the changes in visfatin mRNA expression of adipose tissue suggests paracrine effect of visfatin rather than endocrine. Negative correlation of visfatin VAT mRNA expression with anthropometric parameters indicates important role of VAT visfatin in maturation and in glucose metabolism.

Cancer incidences in the digestive tube: is cobalamin a small intestine cytoprotector?

Malignancies are common in the digestive tube, although with unequal distribution among segments. The aim of this paper was to compare available interpretations of the low cancer incidence in the small bowel and high in the large bowel. Supposed mechanisms include relatively small bacterial population, large secretion of liquid and rapid transit in the small bowel. Small bowel mucosa is the main absorptive part of the digestive tube with absorption rates for various nutrients so high that they can even be considered as clearances from the intestinal content. Consequently, these nutrients are not present in the large bowel. An alternative explanation is that an absorbable protective substance from the intraluminal content, might protect the mucosa from malignant transformations. It can be speculated that if there are any cytoprotective substances in the digested food their effect would be expressed mostly in the absorptive small intestine, leaving the large bowel mucosa unprotected. Vitamin B12 might be a possible candidate for this role. Cobalamin molecules are initially bound to haptocorrin (Hc) in the stomach, but in the small intestine B12 is transferred to intrinsic factor (IF) after the action of pancreatic trypsin on Hc. Cobalamin-IF complexes are absorbed in the terminal ileum leaving only a small fraction of B12 to enter the large bowel. We have tried to summarize available data regarding cancer incidences in digestive tube, segmental length and transit times of tube content. Cancer density is calculated as incidence per length and transit speed as length per transit time. Cancer incidences for seven intestinal segments were considered low if they were below one case per 100 000 inhabitants annually, while the low cancer density meant less than six cases per 100 000 inhabitants per metre. For instance, transverse colon was considered as a high cancer incidence place (2.15 cases), with low cancer density (4.3 cases/m). Transit speed more than 0.3 metre/hour was associated with low cancer incidences (accuracy 0.85) and low cancer density segments (accuracy 1.00). Cobalamin availability showed similar distribution, available in low incidence segments and unavailable in high incidence segments. Experimental studies are needed to quantify B12 availability in the large bowel and to determine whether small amounts of B12-IF or, perhaps, B12-haptocorrin complexes are absorbed by the small bowel mucosa. Without that, no cytoprotective effects of B12 in the digestive tube can be expected.