Expression of sialic acids in human adult skeletal muscle tissue.

Investigations mostly in animal models have shown a role of sialic acid in the morphology and functionality of skeletal muscle during development and adult life. Several studies in humans have been performed regarding changes in sialic acid expression in a particular pathology, hereditary inclusion body myopathy, leading to muscular weakness and atrophy, with a similar phenomenon appearing also in sarcopenia of aging. In this study the expression of monomeric and polymeric sialic acids was evaluated in human skeletal muscle during adult life. Surgical biopsies of the Quadriceps femoris muscle from men aged 18-25 years (young group; n=8) and men aged 72-78 (elderly group; n=10) were collected for analysis. Expression of sialic acids was evaluated using lectin histochemistry, associated with enzymatic and chemical treatments to characterize monomeric and polymeric sialic acids. The polysialic acid expression was also evaluated by immunohistochemistry. Various types of sialic acid in the muscle tissue, in different amounts in the study groups, were detected. Monomeric sialic acids decreased in the elderly group compared with the young group, whereas polysialic acid increased. Sialic acid acetylation was present only in the young group. These findings demonstrated that changes in the expression of sialic acids in skeletal muscle tissue may be related to morphofunctional modifications occurring during aging.

Expression and characterization of anionic components in the tubulointerstitial compartment of rat kidney during polymicrobial sepsis.

The aim of the study was to evaluate sialic acids and hyaluronan expression, anionic components important for the structure and function of the renal tubulointerstitial compartment, in the early stages of sepsis. Two groups of rats were used: (1) sham-operated controls; (2) cecal ligation and puncture (CLP) (polymicrobial sepsis model). A search for microbial growth was made in the peritoneal fluid to document infection. Tubular function was evaluated by means of urinary protein loss, urinary Na(+) and urea excretion. Kidney samples were processed to analyze histology, sialic acids (lectin histochemistry) and hyaluronan (immunohistochemistry) expression. Results showed increased urinary protein loss and fractional excretion of Na(+) and urea reduction in the CLP group. Histological changes, particularly in the cortex and in proximal tubules of the CLP group, were observed. In septic rats, compared to controls, sialic acids decreased in amount and their acetylation increased in the tubules, although to a lesser extent in the proximal portion. Hyaluronan was expressed in the medullary interstitium and in a few areas of cortex in controls. In septic rats it increased in the cortical interstitium and appeared in proximal tubules. These results suggest correlation between expression changes of anionic components and tubulointerstitium morphofunctional alterations during sepsis. A role of these molecules in protection/defense and repair processes may be suggested.

Distribution of sugar residues in human placentas from pregnancies complicated by hypertensive disorders.

The aim of the study was to investigate the content and distribution of sugar residues in placentas from pregnancies complicated by hypertensive disorders. Placentas from women with uncomplicated pregnancies (group 1), pregnancies complicated by gestational hypertension (group 2), pregnancies complicated by pre-eclampsia (group 3), pregnancies complicated by pre-eclampsia with HELLP syndrome (hemolysis, elevated liver enzymes and low platelets) (group 4) were collected. Lectins: ConA, WGA, PNA, SBA, DBA, UEA I, GNA, DSA, MAA, SNA, in combination with chemical and enzymatic treatments, were used. Data showed a decrease and/or lack of α-d-mannose, α-d-glucose and d-galactose-(ß1-4)-N-acetyl-d-glucosamine in placentas from pre-eclampsia and pre-eclampsia with HELLP syndrome compared with control and hypertension cases. N-acetyl-d-galactosamine appeared and/or increased in placentas from hypertensive disorders. A different distribution of various types of sialic acid was observed in placentas from hypertensive disorders compared with the controls. In particular, placentas from pre-eclampsia, with and without HELLP syndrome, lacked the acetylated sialic acid side-chain. These findings demonstrate various alterations of the carbohydrate metabolism in the placentas from pregnancies complicated by different types of hypertensive disorders. This indicates correlation with the placental morpho-functional changes characteristic of these complications and with the degree of clinical severity.