Glucose-induced microvascular functional changes in nondiabetic rats are stereospecific and are prevented by an aldose reductase inhibitor.

Exposure of skin chamber granulation tissue vessels in nondiabetic rats to 11 or 15 mM D-glucose (but not L-glucose or 3-O-methylglucose) twice daily for 10 d induces vascular functional changes (increased albumin permeation and blood flow) identical to those in animals with mild or severe streptozotocin diabetes, respectively. These vascular changes are strongly linked to increased metabolism of glucose via the sorbitol pathway and are independent of nonenzymatic glycosylation as well as systemic metabolic and hormonal imbalances associated with the diabetic milieu. (J. Clin. Invest. 1990. 85:1167-1172.)

Prevention of hemodynamic and vascular albumin filtration changes in diabetic rats by aldose reductase inhibitors.

This study investigated hemodynamic changes in diabetic rats and their relationship to changes in vascular albumin permeation and increased metabolism of glucose to sorbitol. The effects of 6 wk of streptozocin-induced diabetes and three structurally different inhibitors of aldose reductase were examined on 1) regional blood flow (assessed with 15-microns 85Sr-labeled microspheres) and vascular permeation by 125I-labeled bovine serum albumin (BSA) and 2) glomerular filtration rate (assessed by plasma clearance of 57Co-labeled EDTA) and urinary albumin excretion (determined by radial immunodiffusion assay). In diabetic rats, blood flow was significantly increased in ocular tissues (anterior uvea, posterior uvea, retina, and optic nerve), sciatic nerve, kidney, new granulation tissue, cecum, and brain. 125I-BSA permeation was increased in all of these tissues except brain. Glomerular filtration rate and 24-h urinary albumin excretion were increased 2- and 29-fold, respectively, in diabetic rats. All three aldose reductase inhibitors completely prevented or markedly reduced these hemodynamic and vascular filtration changes and increases in tissue sorbitol levels in the anterior uvea, posterior uvea, retina, sciatic nerve, and granulation tissue. These observations indicate that early diabetes-induced hemodynamic changes and increased vascular albumin permeation and urinary albumin excretion are aldose reductase-linked phenomena. Discordant effects of aldose reductase inhibitors on blood flow and vascular albumin permeation in some tissues suggest that increased vascular albumin permeation is not entirely attributable to hemodynamic changes. We hypothesize that 1) increases in blood flow may reflect impaired contractile function of smooth muscle cells in resistance arterioles and 2) increases in vascular 125I-BSA permeation and urinary albumin excretion reflect impaired vascular barrier functional integrity in addition to increased hydraulic conductance secondary to microvascular hypertension associated with decreased vascular resistance.

Increased vascular permeability in spontaneously diabetic BB/W rats and in rats with mild versus severe streptozocin-induced diabetes. Prevention by aldose reductase inhibitors and castration.

125I-labeled albumin permeation (IAP) has been assessed in various tissues in spontaneously diabetic insulin-dependent female BB/W rats and in male Sprague-Dawley rats with severe or mild forms of streptozocin-induced diabetes (SS-D and MS-D, respectively). In BB/W diabetic rats and in rats with SS-D, indices of IAP were significantly increased in tissues and vessels predisposed to diabetic vascular disease in humans, including the eyes (anterior uvea, posterior uvea, and retina), sciatic nerve, aorta, kidney, and new vessels formed after induction of diabetes. No evidence of increased IAP was observed in heart, brain, testes, or skeletal muscle in BB/W or SS-D rats. In MS-D rats, indices of IAP were increased only in the kidney and in new vessels formed after the onset of diabetes. Marked tissue differences were observed in the effects of two structurally different aldose reductase inhibitors (sorbinil and tolrestat) and of castration on diabetes-induced increases in IAP and in tissue levels of polyols in SS-D rats. Both aldose reductase inhibitors and castration completely prevented diabetes-induced increases in IAP in new vessels and in sciatic nerve in BB/W and SS-D rats. Both aldose reductase inhibitors also markedly decreased IAP in the anterior uvea (approximately 85%), posterior uvea (approximately 65-75%), retina (approximately 65-70%), and kidney (approximately 70-100%); castration reduced IAP in the anterior uvea (approximately 55%), kidney (approximately 50%), and retina (approximately 30%) but had no effect on the posterior uvea. The diabetes-induced increases in IAP in the aorta were reduced only slightly (approximately 20%) by aldose reductase inhibitors and castration.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of hemodynamic and vascular filtration changes in diabetic rats by dietary myo-inositol.

To assess the potential of myo-inositol-supplemented diets to prevent diabetes-induced vascular functional changes, we examined the effects of diets supplemented with 0.5, 1, or 2% myo-inositol on blood flow and vascular filtration function in nondiabetic control rats and rats with streptozocin-induced diabetes (STZ-D). After 1 mo of diabetes and dietary myo-inositol supplementation, 1) 131I-labeled bovine serum albumin (BSA) permeation of vessels was assessed in multiple tissues, 2) glomerular filtration rate (GFR) was estimated as renal plasma clearance of 57Co-labeled EDTA, 3) regional blood flows were measured with 15-microns 85Sr-labeled microspheres, and 4) endogenous albumin and IgG urinary excretion rates were quantified by radial immunodiffusion assay. In STZ-D rats, 131I-BSA tissue clearance increased significantly (2- to 4-fold) in the anterior uvea, choroid-sclera, retina, sciatic nerve, aorta, new granulation tissue, diaphragm, and kidney but was unchanged in skin, forelimb muscle, and heart. myo-Inositol-supplemented diets reduced diabetes-induced increases in 131I-BSA clearance (in a dose-dependent manner) in all tissues; however, only in new granulation tissue and diaphragm did the 2% myo-inositol diet completely normalize vascular albumin permeation. Diabetes-induced increases in GFR and in urinary albumin and IgG excretion were also substantially reduced or normalized by dietary myo-inositol supplements. Increased blood flow in anterior uvea, choroid-sclera, kidney, new granulation tissue, and skeletal muscle in STZ-D rats also was substantially reduced or normalized by the 2% myo-inositol diet. myo-Inositol had minimal if any effects on the above parameters in control rats. These observations indicate that diabetes-induced increases in regional blood flow, 131I-BSA permeation, GFR, and urinary protein excretion can be markedly reduced or normalized by consumption of myo-inositol-supplemented diets that raise plasma myo-inositol levels approximately fivefold. The failure of the 2% myo-inositol diet to normalize GFR and blood flow and albumin permeation in several tissues despite markedly elevated plasma myo-inositol levels and normal or elevated tissue myo-inositol levels indicates that if vascular functional changes in these tissues are linked to altered myo-inositol levels, they are resistant to normalization by elevation of plasma myo-inositol levels. These results suggest that other factors independent of changes in relative or absolute tissue myo-inositol levels may play an important role in the pathogenesis of diabetes-induced vascular functional changes in these tissues.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of islet isografts on hemodynamic and vascular filtration changes in diabetic rats.

To assess the reversibility of diabetes-induced increases in regional vascular albumin permeation and blood flow and changes in kidney filtration function, islet isografts were given via the portal vein after 2 mo of streptozocin-induced diabetes in male Lewis rats. One month later, vascular function was assessed in control rats, islet-transplanted diabetic rats, and untreated diabetic rats (6-9 rats/group). Untreated diabetic rats were markedly hyperglycemic, hyperphagic, and polyuric. Transplanted rats were euglycemic within 6 days; 24-h urine volumes were virtually normalized by 2 wk and food consumption was normalized 4 wk after transplantation. Vascular albumin permeation in diabetic rats was significantly increased 1.4- to 1.7-fold in anterior uvea, choroid, retina, sciatic nerve, new granulation tissue, and kidney and was increased 1.1- to 1.3-fold in diaphragm, cecum, and optic nerve. Albumin permeation was not increased in aorta, brain, heart, or forelimb skeletal muscle. Islet transplants significantly reduced but did not completely normalize vascular albumin permeation in most tissues in which it was increased by diabetes but had no effect on albumin permeation in optic nerve, sciatic nerve, and diaphragm. Urinary excretion of endogenous albumin and IgG in diabetic rats was significantly increased 19- and 14-fold, respectively, and was virtually normalized 4 days after islet transplantation. Marked (1.8-fold) increases in glomerular filtration rate (GFR) in diabetic rats were also substantially reduced by islet transplants but remained elevated 1.4-fold control values. Likewise, diabetes-induced increases in regional blood flow were reduced in general but not normalized by islet transplants. These observations indicate that 1) diabetes-induced hemodynamic changes and alterations in vascular filtration function are not rapidly reversed by euglycemia after islet transplantation, 2) diabetes-induced increases in urinary albumin and IgG excretion are more readily normalized by euglycemia than increases in GFR and renal 125I-labeled bovine serum albumin (125I-BSA) filtration, and 3) significant increases in GFR and renal 125I-BSA filtration may not be manifested by albuminuria.

Increased ocular blood flow and 125I-albumin permeation in galactose-fed rats: inhibition by sorbinil.

125I-Albumin permeation and blood flow (assessed with 15 micron, 85Sr-labelled microspheres) were determined in the retina, choroid, anterior uvea, and brain of male Sprague-Dawley rats fed diets containing 50% dextrin (control) or 50% galactose. Blood flow was increased in the retina, choroid, and anterior uvea but not in the brain of rats fed galactose for 3 weeks and 3 months versus controls, and was normalized by sorbinil (an inhibitor of aldose reductase) in the 3-week group. After 8 months of galactose feeding, blood flow was reduced to normal levels in the retina and was slightly below normal in the choroid; blood flow remained elevated in the anterior uvea but was significantly lower than that observed at 3 weeks and at 3 months. In rats fed galactose for 8 months, sorbinil completely normalized blood flow in the choroid, and decreased, but did not normalize, blood flow in the anterior uvea. 125I-Albumin permeation was increased in the retina, choroid, and anterior uvea of rats fed 50% galactose for 3 weeks, 3 months, and 8 months versus controls, but was unchanged in the brain. Sorbinil normalized 125I-albumin permeation in all three ocular tissues in 8-month galactose-fed rats. Polyol levels were increased significantly in all three ocular tissues of 3-week galactose-fed rats; sorbinil markedly decreased, but did not normalize, polyol levels in all three tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Bimolane: in vitro inhibitor of human topoisomerase II.

Bimolane is a member of the bis(2,6-dioxopiperazine) class of drugs and has been widely used in China as an anti-neoplastic agent and for the treatment of psoriasis. Recent case reports indicate that bimolane is leukemogenic and is thought to exert its effects through the inhibition of topoisomerase II. However, there are no data showing the inhibition of topoisomerase II by this agent. In this report bimolane was shown to inhibit the activity of human topoisomerase II in vitro at concentrations of 100 microM and higher when pBR322 was used as the DNA substrate, whereas inhibition was seen at 1.5 mM when using kDNA as a substrate. The results of enzyme and DNA titration assays indicate that inhibition of topoisomerase II by bimolane occurred through interactions with DNA, similar to the mechanism seen with the epipodophyllotoxin-type inhibitors. These results provide evidence that bimolane is an inhibitor of topoisomerase II in vitro.

Nonlinear resonance effects during ion storage in a quadrupole ion trap.

Contributions of higher-order fields to the quadrupolar storage field produce nonlinear resonances in the quadrupole ion trap. Storing ions with secular frequencies corresponding to these nonlinear resonances allows absorption of power from the higher-order fields. This results in increased axial and radial amplitudes which can cause ion ejection and collision-induced dissociation (CID). Experiments employing long storage times and/or high ion populations, such as chemical ionization, ion-molecule reaction studies, and resonance excitation CID, can be particularly susceptible to nonlinear resonance effects. The effects of higher-order fields on stored ions are presented and the influence of instrumental parameters such as radiofrequency and direct current voltage (qZ and az values), ion population, and storage time are discussed.

Characterization of the tumour necrosis factor receptor in human placenta.

A specific receptor for tumour necrosis factor present in a purified plasma membrane preparation from the villous tissue of human placenta has been characterized. The data fit a one-class-of-sites model exhibiting a KD = 28.4 (+/- 0.002) nM, with 8.1 (+/- 0.05) X 10(11) receptors mg-1 membrane protein. These data provide evidence for the existence of a specific receptor for a major endotoxin-induced cytokine in the placenta.

Nicotine effects on proliferation and the bombesin-like peptide autocrine system in human small cell lung carcinoma SHP77 cells in culture.

OBJECTIVES: To determine whether nicotine affects the proliferation and expression of the bombesin-like peptide autocrine system in human small cell lung carcinoma (SCLC) SHP77 cells compared with nonmalignant human bronchial epithelial BEAS 2B cells as non-neuroendocrine controls. METHODS: Human lung cells were cultured in defined serum-free medium with various concentrations of nicotine added for various times. Proliferation was measured by cell counts and colorimetric assay, bombesin-like peptide receptor expression was assayed by specific binding assays and quantitative competitive PCR, and bombesin-like peptides determined by ELISA. RESULTS: Nicotine significantly stimulated the growth of human SCLC SHP77 and NCI-H865 cells, but not BEAS 2B cells. Bombesin-like peptide receptor specific binding and mRNA expression were not affected by nicotine exposure in SHP77 cells or BEAS 2B cells. An increase in SHP77 cellular bombesin-like peptide content was observed. CONCLUSIONS: Human SCLC SHP77 cells express the components of the bombesin-like peptide autocrine system. Increased proliferation in the presence of nicotine may be due in part to increased levels of bombesin-like peptides in SHP77 cultured in nicotine. Nicotine effects on nonmalignant pulmonary neuroendocrine cells may provide additional insight into how nicotine itself may promote lung carcinogenesis.

Quantitative determination of LSD and a major metabolite, 2-oxo-3-hydroxy-LSD, in human urine by solid-phase extraction and gas chromatography-tandem mass spectrometry.

An assay has been developed for quantitative determination of lysergic acid diethylamide (LSD) and a major metabolite of LSD in human urine at concentrations as low as 10 pg/mL. In most LSD-positive urine samples the metabolite, 2-oxo-3-hydroxy-LSD, is present at higher concentrations than LSD and can be detected for a longer time than LSD after ingestion of the drug. Urine samples are extracted using Varian Bond Elut Certify extraction cartridges. Confirmatory identification is accomplished by trimethylsilylation of LSD and 2-oxo-3-hydroxy-LSD, followed by gas chromatography-tandem mass spectrometry analysis using positive ion chemical ionization and selected reaction monitoring. Commercially available lysergic acid methylpropylamide and 2-oxo-3-hydroxy-LAMPA are used as internal standards. With selected reaction monitoring, both compounds gave linear calibration curves from 10 pg/mL to 5000 pg/mL. Forty-nine human urine samples that had previously been shown to contain LSD were reanalyzed by the new method. These samples showed an average LSD concentration of 357 pg/mL and an average 2-oxo-3-hydroxy-LSD concentration of 3470 pg/mL. Additional experiments using clinical samples in which two subjects were dosed with LSD support the conclusion that analysis for 2-oxo-3-hydroxy-LSD can permit identification of LSD users for a longer period following ingestion than analysis for the parent drug.

Observation of soliton compression in silicon photonic crystals.

Solitons are nonlinear waves present in diverse physical systems including plasmas, water surfaces and optics. In silicon, the presence of two photon absorption and accompanying free carriers strongly perturb the canonical dynamics of optical solitons. Here we report the first experimental demonstration of soliton-effect pulse compression of picosecond pulses in silicon, despite two photon absorption and free carriers. Here we achieve compression of 3.7 ps pulses to 1.6 ps with <10 pJ energy. We demonstrate a ~1-ps free-carrier-induced pulse acceleration and show that picosecond input pulses are critical to these observations. These experiments are enabled by a dispersion-engineered slow-light photonic crystal waveguide and an ultra-sensitive frequency-resolved electrical gating technique to detect the ultralow energies in the nanostructured device. Strong agreement with a nonlinear Schrödinger model confirms the measurements. These results further our understanding of nonlinear waves in silicon and open the way to soliton-based functionalities in complementary metal-oxide-semiconductor-compatible platforms.

Rapid analysis of sorbitol, galactitol, mannitol and myoinositol mixtures from biological sources.

The three commonly found hexitols mannitol, sorbitol and galactitol are well separated from each other and from myoinositol by gas chromatography as their butylboronate derivative on Dexsil-400, on a 1:1 mixture of OV-1 and OV-17, or on a DB-17 fused-silica capillary column. The method allows all four substances to be measured by autosampling electron ionization gas chromatography-mass spectrometry (GC-MS) in small tissue samples at organ concentrations as small as 5 mumol/kg wet mass in less than 4 min. Comparisons were made to determine the relative sensitivity of GC-MS and other detection methods. The order of sensitivity was electron ionization GC-MS greater than chemical ionization GC-MS greater than flame photometric detection using a boron-selective filter greater than hydrogen flame ionization detection.

Recent advances in chromatographic and mass spectrometric methods for determination of LSD and its metabolites in physiological specimens.

The detection of LSD use continues to be a challenge for toxicology laboratories due to the very low concentrations of LSD and its metabolites in body fluids. However, significant progress has been made in the development of more sensitive and specific analytical methods. Techniques that have proven particularly effective include: (1) immunoaffinity extraction, (2) gas chromatography coupled with chemical ionization and tandem mass spectrometric detection, and (3) liquid chromatography in combination with electrospray ionization and either single-stage or tandem mass spectrometric detection. In addition, a major metabolite of LSD, 2-oxo-3-hydroxy-LSD, has been identified and found to be present in far higher concentrations than LSD in most LSD-positive urine samples.

Serial changes in humoral and cellular immunity induced by prostaglandin E2 treatment of murine immune complex glomerulonephritis.

To examine the mechanism by which prostaglandin E2 (PGE2) inhibits the development of apoferritin (HAF)-induced immune complex glomerulonephritis (ICGN), weekly determinations of glomerular histologic conditions, blood urea nitrogen (BUN), total immunoglobulin levels, anti-HAF antibody, peripheral blood and splenic T cell subsets, and splenic suppressor cell activity were compared between mice receiving HAF and mice additionally treated with PGE2. PGE2 therapy prevented the development of glomerular hypercellularity and the increase in BUN concentration. Administration of PGE2 reduced anti-HAF IgG levels, but total IgM and IgG1, IgG2a, and IgG2b levels were unchanged. Mice receiving HAF alone demonstrated serial reductions in phenotypically identified peripheral blood pan-T cells and suppressor-cytotoxic T cells. PGE2-treated mice maintained normal levels of peripheral blood T cell subsets. Significant reductions in splenic total T cells and suppressor-cytotoxic cells occurred in mice receiving HAF as compared with normal mice. This reduction was offset by an increase in splenic B cells. PGE2 therapy prevented the decrease in splenic T cells at week 1, but not at week 4. Nonspecific suppressor cell activity, as measured by the ability of spleen cells from experimental mice to suppress a mixed lymphocyte reaction (MLR) or to suppress MLR-induced polyclonal IgG synthesis, was not different between the two groups. We conclude that prevention of HAF-ICGN by PGE2 is associated with a reduction in nephritogenic antibody production without an alteration in total immunoglobulin synthesis or the generation of nonspecific suppressor T cells. Changes in the percent of peripheral blood and splenic T cells and B cells may represent an effect of PGE2 on antigen-stimulated B cell proliferation.

Alterations in serum antibody and peripheral T-lymphocyte subsets resulting from treatment of murine immune complex glomerulonephritis with PGE2.

The effects of treatment with 16,16-dimethyl prostaglandin E2 (DMPGE2) on histologic damage, glomerular immune complex deposition, serum total IgG subclass levels, anti-apoferritin IgG levels, and peripheral blood T-lymphocyte subsets were determined in apoferritin-induced immune complex glomerulonephritis of mice. The results demonstrate that doses of DMPGE2 ranging from 2.5 to 10 micrograms twice daily significantly reduced the degree of glomerular damage in a dose-dependent manner. Similarly, these doses of DMPGE2 reduced the amount of immunoglobulin deposition along peripheral capillary loops. Total IgM, IgG1, IgG2a, and IgG2b were unaffected by DMPGE2 administration. Serum anti-apoferritin IgG levels were significantly reduced in mice receiving DMPGE2 at doses of 5 and 10 micrograms twice daily. Nephrotic mice had significantly reduced peripheral blood total T lymphocytes (Lyt-1+) and a reduction of T-suppressor (Lyt-2+) cells. Administration of DMPGE2 at doses of 5 and 10 micrograms twice daily prevented these T-lymphocyte alterations. These studies indicate that treatment of mice receiving apoferritin with DMPGE2 may prevent glomerulonephritis by altering both cellular and humoral immune responses.

Effects of very mild versus overt diabetes on vascular haemodynamics and barrier function in rats.

Rats injected i.p. with a single dose of nicotinamide (250 mg/kg) 15 min prior to i.v. injection of streptozotocin (65 mg/kg) develop a very mild form of diabetes characterized by slight elevations of plasma glucose, increased levels of HbA1, and reduced insulin secretion in response to an i.v. glucose tolerance test. These rats gain weight normally and they are not hyperphagic, glycosuric, or polyuric. The effects of this very mild form of diabetes vs overt streptozotocin diabetes of three months duration on regional vascular 131I-albumin clearance, blood flow (assessed by 15 microns 85Sr-microspheres), and renal filtration function were examined in male Sprague-Dawley rats. Plasma glucose levels of rats with mild diabetes were 7.4 +/- 0.9 (mean +/- SD) (mmol/l) vs 6.5 +/- 0.6 for control rats and 31.3 +/- 6.0 for overtly diabetic rats. HbA1 levels were increased 1.4 fold in mildly diabetic and 2.3 fold in overtly diabetic rats. Vascular clearance of 131I-albumin was markedly increased in ocular tissues (anterior uvea, retina, and choroid), sciatic nerve, aorta, new (subcutaneous) granulation tissue, and kidney of both diabetic groups, although increases in overtly diabetic rats exceeded those in the mildly diabetic group (2.2-4.6 times control animals vs 1.6-3.3 times, respectively). Likewise, both overt and very mild diabetes markedly increased glomerular filtration rate (approximately 1.8 times and 1.2 times control animals, respectively), urinary excretion of endogenous albumin (approximately 9 times and 4 times) and IgG (approximately 15 times and 4 times), as well as regional blood flow in the anterior uvea, choroid, and sciatic nerve. Increases in tissue sorbitol levels were much larger in overtly diabetic rats (generally 10-20 times control animals) than in mildly diabetic rats (1.5-3 times controls). myo-Inositol levels were significantly decreased only in lens and sciatic nerve of overtly diabetic rats. These observations indicate that even very mild diabetes is associated with vascular functional changes which develop more slowly than in overtly diabetic rats, but are disproportionately large (in view of the minimal increases in glycaemia and tissue polyol levels) compared to those in overtly diabetic rats.