Novel fluorinated surfactants for perfluorochemical emulsification: biocompatibility assessments of glycosidic and polyol derivatives.

A novel series of fluoro-surfactants, derived from glycosides (monosaccharides) or polyols (ureas or carbamates), have been produced for use in respiratory gas-carrying perfluorochemical emulsions. Compounds were synthesised via simple, but highly selective, routes using highly fluorinated isocyanates with amino alcohols, polyethoxylated alcohols and partially protected sugars at anomeric carbon; yields were 88-95%. Resultant compounds were perfluoroalkylated with hydroxylic "head" groups. The biocompatibility of surfactants with human blood in vitro was assessed using a conventional haemolysis test. Compounds showing insignificant haemolysis at up to 10 g l-1 were further evaluated (i) for their effects on neutrophil chemiluminescence, and (ii) in a human platelet aggregation assay. Some fluoro-surfactants inhibited spontaneous platelet aggregation, in blood anti-coagulated with hirudin, at concentrations of 0.01% (w/v), suggesting possible applications as antithrombotic agents.

Effect of hyperglycemia on the polyol pathway in rat kidney during the perinatal period.

The activity of the polyol pathway was studied in developing rat kidney. For this purpose, sorbitol content, aldose-reductase activity and sorbitol-dehydrogenase activity were determined in papilla from fetuses and 24-h-old neonates. After birth, no significant difference was observed in sorbitol content, whereas sorbitol-dehydrogenase activity decreased and aldose-reductase activity doubled. Changes in aldose-reductase activity were due to an increased number of enzymatic sites but not with a change in affinity. Low levels of sorbitol were found in fetal and neonatal medulla together with low levels of urine osmolarity. In neonates, sorbitol contents were tenfold lower than in the adult, probably as a result of a lower affinity and a lower number of enzymatic aldose-reductase sites. Attempts to increase the activity of polyol pathway in fetal kidney were made by means of hyperglycemic animals; this approach resulted in an increase of aldose-reductase activity without any change in sorbitol content. Our results indicate that, in fetal and neonatal kidneys, aldose-reductase activity is probably not the limiting factor for sorbitol synthesis; another parameter, such as the availability of NADPH, might explain the low efficiency of the polyol pathway during the perinatal period.

Prevention of early glomerulopathy with tolrestat in the streptozotocin-induced diabetic rat.

Hyperglycemia is of central importance in the pathogenesis of the complications of diabetes mellitus. Glucose activation of the polyol pathway may lead to renal arteriolar smooth muscle and glomerular mesangial cell hypocontractility. In the streptozotocin-induced diabetic rat, the effect of the aldose reductase inhibitor, tolrestat, in preventing glomerular hyperfiltration, renal hypertrophy, extracellular matrix accumulation, and mesangial cell hypocontractility was addressed. Streptozotocin-induced diabetic rats were followed for 12 weeks and half received tolrestat (25 mg/kg per day). Increased glomerular filtration rate was prevented by tolrestat (3.1 +/- 0.3 vs. 1.8 +/- 0.2 mL/min, diabetes vs. diabetes + tolrestat, p < 0.01), in part by reduction of the filtration fraction (0.39 +/- 0.03 vs. 0.29 +/- 0.01, diabetes vs. diabetes + tolrestat, p < 0.01). Tolrestat prevented the raised albumin excretion rates (3594 +/- 1154 vs. 713 +/- 161 mg/24 h, diabetes vs. diabetes + tolrestat, p < 0.01). Endothelin-1-induced contraction of isolated glomeruli was normal in tolrestat-treated diabetic animals compared with the hypocontractile diabetic glomeruli. Tolrestat prevented glomerular hypertrophy (1.86 +/- 0.10 vs. 1.49 +/- 0.03 microns 2 x 10(5), diabetes vs. diabetes + tolrestat, p < 0.001) and attenuated the accumulation of basement-membrane-like material (50.2 +/- 0.4% vs. 46.4 +/- 0.8%, diabetes vs. diabetes+tolrestat, p < 0.001). Fractional mesangial expansion was unchanged in tolrestat-treated diabetic rats compared with untreated animals. Tolrestat prevents the functional changes of glomerular hyperfiltration, mesangial cell hypocontractility, and increased glomerular permeability to albumin. Polyol accumulation may have differential effects on glomerular growth and extracellular matrix accumulation in early diabetic nephropathy.

An aldose reductase inhibitor, TAT, reduces ADP-induced platelet hyperaggregation in streptozotocin-induced diabetic rats with neuropathy.

To investigate the relationship between metabolic and vascular factors, especially polyol pathway and platelet aggregation, in the pathogenesis of diabetic neuropathy, the effects of a novel potent aldose reductase inhibitor, TAT ((5-(3-thienyl) tetrazol-1-yl) acetic acid monohydrate) on adenosine diphosphate-induced platelet aggregation, polyol contents in platelets, motor nerve conduction velocity (MNCV), and sciatic nerve blood flow (SNBF) were examined in streptozotocin-induced diabetic rats. Diabetic rats demonstrated hyperaggregation in response to adenosine diphosphate, accompanied by sorbitol and fructose accumulation and myoinositol depletion in platelets. Treatment with TAT improved these abnormalities in diabetic rats. A delayed MNCV and a reduced SNBF in diabetic rats were normalized by the administration of TAT. These observations suggest that increased polyol pathway activity plays an important role in platelet aggregation in the development of diabetic neuropathy and that aldose reductase inhibitor is useful for the treatment of diabetic neuropathy from the viewpoint not only of metabolic factors but also of vascular factors.

Volumetric properties of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol and mannitol) in relation to their membrane permeability: group additivity and estimation of the maximum radius of their molecules.

The relationship of molecular volume and maximum molecular radii to the ability of some polyols, ethylene glycol, glycerol and meso-erythritol, to permeate the Chara cell membrane and to the inability of one of the polyols, mannitol, to permeate the Chara cell membrane, was examined by measuring the partial molar volumes of the polyols, Vm(2). Analysis of Vm(2) at infinite dilution showed that group additivity is maintained for all the groups, i.e., CH2OH and CHOH, of the polyols tested. However, as the permeability and impermeability could not be related to the geometrical properties of the polyol molecules based only on the thermodynamic quantities, molecular models of the polyol molecules were constructed using the CPK(Corey-Pauling Koltum) molecular model, which is designed to have the van der Waals radius of 1 A equivalent to 1.25 cm. The results showed that the maximum radius of the water-filled pore (hydrophilic channel) should be 3.2-3.3 A, and the longer the axial length and maximum radius of the polyol molecule, the lesser was its permeative ability. All the experimental and analytical results and inferences support the idea that water molecules pass across the cell membrane through a narrow pore in a single-file fashion.

Polyol and vacuole formation in cultured canine lens epithelial cells.

Polyol accumulation and myo-inositol depletion were accompanied by extensive vacuole formation in cultured canine lens epithelial cells that were incubated for up to 96 hr in growth medium supplemented with 30 mM D-galactose or 30 mM D-glucose. These changes did not occur in cells incubated in a hypergalactosemic or hyperglycemic medium which also contained an aldose reductase inhibitor (20 microM sorbinil). In addition, these changes were not observed in lens cells incubated in growth medium supplemented with either 30 mM mannitol, which is known to enter cells only slowly, or in 30 mM L-galactose, which is not a substrate for aldose reductase. The vacuoles were visible at the ultrastructural level after 6 hr of incubation in 30 mM D-galactose and increased in both number and size with time. These vacuoles had a unique fine structure. They did not result from swelling of mitochondria or other cell organelles. As demonstrated cytochemically, they did not represent either lysosomes or Golgi saccules. The proliferation pattern of cells incubated with 30 mM D-galactose was clearly different from that of control cells, but approached normal when an aldose reductase inhibitor was added to the incubation medium. Together these findings suggest that vacuole formation and altered cell proliferation were caused by polyol accumulation and/or myo-inositol loss, both of which result from aldose reductase activity.