Glycated high-density lipoprotein regulates reactive oxygen species and reactive nitrogen species in endothelial cells

Nonenzymatic glycosylation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Although it is believed that high-density lipoprotein (HDL) is glycosylated at an increased level in diabetic individuals, little is known about a possible linkage between glycated HDL and endothelial dysfunction in diabetes. To clarify whether glucose-modified HDL affects the function of endothelial cells, we first examined herein the level of H(2)O(2) generation from cultured human aortic endothelial cells (HAECs) exposed to a glycated oxidized HDL (gly-ox-HDL) prepared in vitro. Incubation for 48 hours with 100 microg/mL of gly-ox-HDL induced significant release of H(2)O(2) from cells and gly-ox-HDL-induced H(2)O(2) formation was inhibited in the presence of diphenyleneiodonium, an inhibitor of NADPH oxidase. In addition, stimulation of HAECs with gly-ox-HDL for 48 hours elicited a marked downregulation of catalase and Cu(2+), Zn(2+)-superoxide dismutase (CuZn-SOD), suggesting H(2)O(2) formation by gly-ox-HDL to be due to a disturbance involving oxidant and antioxidant enzymes in the cells. Treatment of HAECs with gly-ox-HDL attenuated the expression of endothelial nitric oxide synthase (eNOS), but not inducible nitric oxide synthase (iNOS), and this was followed by decreased production of nitric oxide (NO) by the cells. Furthermore, in vitro experiments with glycated HDL (gly-HDL) in the presence of 2 mmol/L EDTA and Cu(2+)-oxidized HDL suggested the effect of gly-HDL on endothelial function to be possibly potentiated by additional oxidative modification. Taking all of the above findings together, gly-ox-HDL may lead to the deterioration of vascular function through altered production of reactive oxygen species and reactive nitrogen species in endothelial cells.     

Sonographically guided core biopsy of the salivary gland masses: safety and efficacy

Over an 8-year period, we performed ultrasonography (US)-guided core biopsy of the salivary gland in 37 patients using an 1l-mm-throw 18-gauge automated biopsy system. The biopsy results were retrospectively compared with the findings of surgical pathology (n=18) or more than 6 months of clinical follow-up (n=19). The sensitivity, specificity, and accuracy of US-guided core biopsy for the diagnosis of malignancy were 75.0%, 96.6%, and 91.9%, respectively. No immediate or delayed complications occurred.     

Excretion of methylhippuric acids in urine of workers exposed to a xylene mixture: comparison among three xylene isomers and toluene

Summary The correlation between exposure to three xylene isomers and resulting urinary excretion of corresponding methylhippuric acid (MHA) isomers was studied among 175 Chinese workers of both sexes who had been predominantly exposed to xylenes (exposure to xylenes accounting for 70% or more of the total exposure on a ppm basis). Nonexposed controls (281 men and women) were also studied to define the background level of MHAs in urine. The solvent exposure of xylene-exposed workers during their workshift was monitored by diffusive sampling of breathing zone air, and MHAs in shift-end urine were determined by high-performance liquid chromatography. Regression analysis showed that the concentration of each MHA isomer correlated significantly with the time-weighted average intensity of exposure to the corresponding xylene isomer, and therefore the correlation between the sum of three xylene isomers in air and that of three MHA isomers in urine was also significant; the slope of the regression line was essentially the same among the three isomers. The calculated regression line suggested that the urinary MHA level after hypothetical exposure to xylenes at 100 ppm will be somewhat less than the proposed biological exposure index and biological tolerance value. Two social habits of smoking and drinking in combination suppressed the conversion of xylenes to MHAs in male workers.     

Frenum-like oral synechiae of the lip and vestibule

Two cases where aberrant tissue was attached to the lower lip mimicking the inferior labial frenum were reported. The frenum-like tissue extended from the gingival margin between the lower left deciduous central and lateral incisors in case 1 and between the lower right deciduous central and lateral incisors in case 2, to the dry lower lip. Histologically, the resected specimen was regarded as normal oral mucosa covered with stratified squamous epithelium, without a clear amniotic band. The frenum-like tissue of the lower lip found in both our patients was diagnosed as a category of oral synechiae, of unknown origin.     

Human alpha 1-microglobulin and its relationship to renal function

To evaluate the clinical usefulness in terms of estimation for glomerular filtration rate (GFR), we determined the levels of alpha 1-microglobulin (alpha 1m) in the serum and urine of patients with various renal diseases and compared with those of beta 2-microglobulin (beta 2m) and creatinine. Serum and urinary alpha 1m levels were measured by using single-radial immunodiffusion method. 24-hour creatinine clearance (Ccr) was used as a indicator of GFR. There was a significant positive correlation between serum alpha 1m and creatinine levels (r = 0.75, p less than 0.001). Serum alpha 1m, beta 2m and creatinine inversely correlated and logarithmically correlated to Ccr as shown in the following equations: log alpha 1m = 2.30 - 0.42 X log Ccr (r = -0.74); log beta 2m = 2.06 - 0.91 X log Ccr (r = -0.92); log creatinine = 1.57 - 0.78 X log Ccr (r = -0.94). Both correlation coefficient and regression coefficient for alpha 1m were rather poor compared to those for beta 2m and creatinine. However, alpha 1m levels started to increase over normal range when Ccr fell below 80 liters/day, while beta 2m and creatinine remained within normal ranges. The daily urinary excretion of alpha 1m was increased in the patients whose Ccr was within normal limits compared to that of healthy control subjects (15.2 +/- 3.2 mg/day, n = 19, vs. 5.7 +/- 0.7, n = 7, p less than 0.001). Fractional clearance of alpha 1m increased proportionally to the decrease of Ccr. These data suggest that combined measurements of alpha 1m in the serum and urine seem to be useful to estimate GFR, especially to detect the mild reduction of CFR.     

Subtractive gene cloning using dynabeads oligo(dT)25 for elucidation of pseudohyphal formation in Candida tropicalis]

The dimorphic transition from yeast to pseudohyphae in Candida tropicalis occurs following the addition of ethanol to a synthetic medium containing glucose. We developed a method of subtractive gene cloning to isolate genes, of which the expression was apparently specific for pseudohyphal formation in this organism. Subtraction was performed between sense-strand cDNAs instead of mRNAs from cells of the ethanol culture and anti-sense cDNAs linking to Dynabeads oligo(dT)25 from those of the control culture. Dynabeads oligo(dT)25 are paramagnetic beads with 25 nucleotide-long chains of deoxythymidines covalently linked to their surface and were expected to be easily collected using a magnet. This method using Dynabeads oligo(dT)25 minimizes the degradation of mRNA and makes it easy to construct a cDNA library sufficient to analyze the genetic information on the yeast-to-hyphae transition. Using this strategy, we identified several genes including a homologue of CPP1 coding tyrosine phosphatase and a homologue of nmt1+ encoding protein, which was reported to regulate thiamine biosynthesis.     

Pacemaker Shift in the Rabbit Sinoatrial Node in Response to Vagal Nerve Stimulation

Effects of brief postganglionic vagal nerve stimulation on the activation sequence of the rabbit sinoatrial (SA) node were investigated. Activation sequences in a small area (7 mm x 7 mm) on the epicardial surface were measured in a beat-to-beat manner using an extracellular potential mapping system composed of 64 modified bipolar electrodes with high-gain and low-frequency band-pass filtering. The leading pacemaker site was recognised clearly from both the activation sequence and the characteristic morphology of the potentials. Vagal stimulation resulted in a short-lasting initial slowing of spontaneous rate followed by a long-lasting secondary slowing; a brief period of relative or absolute acceleration was interposed between the two slowing phases. During these changes of spontaneous rate, the leading pacemaker site shifted in a complex beat-to-beat manner by 1-6 mm alongside the crista terminalis in the superior or inferior direction. For the first spontaneous excitation following stimulation, the greater the slowing, the larger the distance of the pacemaker shift. There was no such linear relationship between the extent of slowing and the distance of pacemaker shift for the subsequent beats. These changes in the leading pacemaker site in response to vagal stimulation may be the result of the functional and morphological heterogeneity of the mammalian SA node in terms of innervation, receptor distribution and ion channel densities. Experimental Physiology (2001) 86.2, 177-184.