Increased serum N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase activities in obese subjects

Caloric restriction prevents inflammation and insulin dysfunction in middle-aged ovariectomized mice

BACKGROUND

Loss of ovarian function is associated with increased visceral fat. In this study, we aimed to study the effects of caloric restriction (CR) on metabolism in ovariectomized mice.

METHODS AND RESULTS

Female, 8-12-month-old mice were divided into three groups: OVX (ovariectomized mice), OVXR (40% CR) and Sham. CR increased insulin sensitivity and glucose tolerance. AMPK phosphorylation was observed in the liver of OVXR mice. CR also increased hepatic cholesterol and triglyceride levels. The reductions in the level of TBARS in the serum and liver and of H2O2 in the liver of OVXR mice suggested alterations in the redox state of the liver. Although expression of catalase protein was reduced by CR, expression of superoxide dismutase was not altered by CR. Although interleukin IL-6 and IL-10 levels in OVXR mice were similar to those in Sham mice, macrophage infiltration was reduced in OVXR mice. OVXR mice had increased sirtuin1 levels and decreased sirtuin3 levels in the liver.

CONCLUSIONS

In conclusion, CR improved the condition of ovariectomized mice by reducing adiposity and increasing insulin sensitivity and glucose tolerance through a mechanism that may involve AMPK.

A locus on mouse Chromosome 9 (Adip5) affects the relative weight of the gonadal but not retroperitoneal adipose depot

To identify the gene or genes on mouse Chromosome 9 that contribute to strain differences in fatness, we conducted an expanded mapping analysis to better define the region where suggestive linkage was found, using the F(2 )generation of an intercross between the C57BL/6ByJ and 129P3/J mouse strains. Six traits were studied: the summed weight of two adipose depots, the weight of each depot, analyzed individually (the gonadal and retroperitoneal depot), and the weight of each depot (summed and individual) relative to body size. We found significant linkage (LOD = 4.6) that accounted for the relative weight of the summed adipose depots, and another for the relative weight of the gonadal (LOD = 5.3) but not retroperitoneal (LOD = 0.9) adipose depot. This linkage is near marker rs30280752 (61.1 Mb, Build 34) and probably is equivalent to the quantitative trait locus (QTL) Adip5. Because the causal gene is unknown, we identified and evaluated several candidates within the confidence interval with functional significance to the body fatness phenotype (Il18, Acat1, Cyp19a1, Crabp1, Man2c1, Neil1, Mpi1, Csk, Lsm16, Adpgk, Bbs4, Hexa, Thsd4, Dpp8, Anxa2, and Lipc). We conclude that the Adip5 locus is specific to the gonadal adipose depot and that a gene or genes near the linkage peak may account for this QTL.

Lysosomal enzymes in preterm infants with bronchopulmonary dysplasia: a potential diagnostic marker

Some lysosomal glycohydrolases (N-acetyl-beta-D-glucosaminidase and their major isoenzymes, beta-D-glucuronidase, alpha-D-galactosidase, beta-D-galactosidase and alpha-D-glucosidase) were investigated in the plasma of 36 preterm infants with respiratory distress, 11 of whom developed bronchopulmonary dysplasia (BPD), in order to evaluate the role of the lysosomal apparatus in the disease. Enzyme activity was assayed fluorimetrically; the major N-acetyl-beta-D-glucosaminidase (NAG) isoenzymes were separated using a routine chromatofocusing procedure; the diagnostic efficiency was evaluated by Bayes theorem. The mean levels of almost all glycohydrolases considered were significantly higher in BPD than in non-BPD infants. Among NAG major isoenzymes, an increase was found only in form A. No variation was evident in the plasma levels of glycohydrolases during dexamethasone therapy. Data from a retrospective analysis performed in all preterms considered, show that alpha-D-galactosidase and beta-D-galactosidase differentiate a posteriori BPD and non-BPD subjects. These enzymes, after a priori verification of their diagnostic potential in preterm infants at risk of BPD development, could acquire an important predictive value.

Plasma lysosomal glycohydrolases in a general population

In this study we evaluated the differences in plasma levels of some glycohydrolases of lysosomal origin that appear to be the most interesting for possible usefulness for diagnosis (N-acetyl-beta-D-glucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-L-fucosidase and alpha-D-mannosidase) in a general population of 417 subjects, as related to age and sex and also to body mass and to some habits, such as smoking and consumption of alcohol. The enzymatic activities were assayed by fluorimetric techniques with 4-methylumbelliferyl-glycosides as substrates. Particular attention was given to some technical aspects. Enzymatic activity was preserved by addition of ethylene glycol and stable liquid material was employed for calibration purposes. Blood was sampled rigorously at the same time of day and all the samples were obtained within a short period of time to exclude effects of the circadian and circannual rhythms. beta-Glucuronidase levels were the most affected by sex and body mass. beta-D-Galactosidase was not affected by differences in age, sex, body mass or by smoking, but appeared to be the most sensitive to modification by alcohol consumption. The data in this report emphasize that, whenever changes or differences in the levels of lysosomal enzymes in body fluids are studied, it is essential to have a reference population rigorously correlated with the study population. When possible, repetitive measurements in the same subject could better indicate a clinical trend.

Quantification of the hemolysis associated with use of T-61 as a euthanasia agent in rabbits--a comparison with Euthanyl (pentobarbital sodium) and the impact on serum hexosaminidase measurements

Albino rabbits (2-2.3 kg) were euthanized with T-61R (N-[2-(m-methoxyphenyl)-2-ethylbutyl-(1)-]-gamma-hydroxybutyram ide, 200 mg/mL; 4,4'-methylene-bis-(cyclohexyltrimethylammonium iodide), 50 mg/mL; tetracaine hydrochloride, 5 mg/mL; 0.2-1.0 mL/kg, i.v.) or EuthanylR (pentobarbital sodium, 100-240 mg/kg, i.v.) at 15:00 h, and samples of arteriovenous blood or venous blood were collected. The time to loss of consciousness was dose dependent for T-61, ranging from 7 to 1 s or less. Serum obtained after T-61 euthanasia, but not after Euthanyl, was routinely contaminated with measurable hemoglobin levels (up to an estimated 3 mg/mL). The extent of hemolysis increased with increasing T-61 doses. The activity of hexosaminidase in the serum (determined by hydrolysis of a methylumbelliferyl substrate at pH 4.6) was up to 80% lower in sera obtained after the use of T-61 compared with sera obtained after the use of Euthanyl or without euthanasia drugs. The reduction in measurable activity appears to be due to interference, by hemoglobin, in the fluorescence measurements of the methylumbelliferol reaction product (with threshold effects being detected at 0.1 mg/mL). Standardization of serum volumes used in these types of enzyme assays and reporting on hemoglobin levels is thus recommended.

The lysosomal N-acetyl-beta-D-glucosaminidase (NAG) isoenzymes in plasma: study of distribution in a general population by a simple routine chromatofocusing procedure

We have adapted for routine analysis a pre-existing method for separating the three major N-acetyl-beta-D-glucosaminidase (NAG) isoenzyme forms--A, B+I1 and I2--by chromatofocusing followed by fluorimetric assay of the enzyme activity. This method combines good resolution, accurate quantification of the different isoenzymes and high reproducibility with an acceptable degree of analytical precision. We have applied it to studying the isoenzyme levels in the plasma of a general population of 417 subjects and have analysed these enzyme activities as functions of age, sex, body mass and declared alcohol consumption. Unlike the levels of unfractionated enzyme, levels of all the isoenzymes were higher in men than in women at all ages except in the 20-29 year group. Isoenzyme I2 showed the greatest sex difference. On the whole, with increasing age, both sexes showed more or less regular increases in plasma levels of all the isoenzymes. We also found significant correlations for the population as a whole with age and with body mass index. The only significant correlation with alcohol consumption was for B+I1 in men.