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At least 991 records · Page 55Linked to original sources
PubMed1989

Effect of antihypertensive treatment on blood-retinal barrier permeability to fluorescein in hypertensive type 1 (insulin-dependent) diabetic patients with background retinopathy.

The effect of antihypertensive treatment on blood-retinal barrier leakage of fluorescein in background retinopathy was studied in nine hypertensive Type 1 (insulin-dependent) diabetic patients suffering from nephropathy. The patients were investigated before and after 7 (3 to 13) months of treatment with captopril (n = 8; 25 to 100 mg daily) and a diuretic, either frusemide (n = 4; 80 to 200 mg daily) or bendrofluazide (n = 2; 2.5 mg daily). Retinal function was assessed by fundus photography, fluorescein angiography, vitreous fluorometry, and renal function by glomerular filtration rate, and albuminuria. The antihypertensive treatment induced a significant reduction (p less than 0.05) in: blood pressure from 152/97 +/- 14/8 mmHg to 134/82 +/- 11/6 mmHg; blood-retinal barrier leakage of fluorescein from 2.4 +/- 1.1 to 1.4 +/- 0.5.10(-7) cm/second; albuminuria from 1391 (range: 168-4852) micrograms/min to 793 (range: 35-2081) micrograms/min. Glomerular filtration rate declined from 88 +/- 15 to 78 +/- 23 ml.min-1.1.73 m2 (0.05 less than p less than 0.10). The metabolic control of the patients as reflected by their blood glucose and HbA1c levels remained stable during the study. Our study suggests that systemic blood pressure elevation contributes to the abnormal blood-retinal barrier permeability to fluorescein characteristically found in diabetic background retinopathy and that this abnormality can be reversed during antihypertensive treatment.

Adult↗
PubMed1975

Molecular basis of chromosome banding. II. The effect of silver and mercury ions on the fluorescence intensity of acranil-DNA complexes.

Silver and mercury ions are known to react with the bases of nucleic acids in solution. At low cation/base ratios Ag+ has an affinity for GC pairs in DNA, whereas Hg++ is preferentially bound to AT-rich nucleic acids. We have used fluorometry to measure the effect of these cations on the fluorescence intensity of preformed complexes of acranil and DNA in solution. The results are: 1) Ag+ enhances the fluorescence intensity presumably by affecting the dye intercalated in the vicinity of GC-pairs. 2) The addition of Hg++ leads to a quenching of the fluorescence intensity of the complex at low ion/base ratios, suggesting an effect on the dye molecules bound to AT pairs. At high GC-content of the nucleic acid, slight enhancement of the fluorescence intensity occurs with Hg++. 3) With both metals there is a correlation between base content of DNA and effect on the intensity of fluorescence indicating base specificity of the dye-polymer interaction.

Acridines↗
PubMed1987

Effect of exposure to carbon disulfide on tryptophan metabolism and the tissue vitamin B6 contents of rats.

Female Wistar rats were exposed to 100 ppm or 600 ppm carbon disulfide for 6 hours a day, 5 days a week for 12 weeks. During the exposure period, their urinary excretion of 4-pyridoxic acid was determined. The urinary excretions of xanthurenic acid and kynurenic acid after tryptophan loading were also determined. At the end of the exposure period, the rats were sacrificed and the levels of the five major forms of vitamin B6, pyridoxine, pyridoxal, pyridoxamine, pyridoxal phosphate and pyridoxamine phosphate, in the liver, kidneys and brain were determined by HPLC fluorometry. During the exposure the urinary excretions of xanthurenic acid and kynurenic acid after i.p. administration of tryptophan increased significantly in both experimental groups. However, urinary excretion of 4-pyridoxic acid decreased only slightly in the group exposed to carbon disulfide at 600 ppm and did not decrease in the group exposed to 100 ppm carbon disulfide. Furthermore, no significant changes were observed in the contents of vitamins B6 in any tissues examined. These results indicate that carbon disulfide does not cause vitamin B6 deficiency and thus that the disorders of tryptophan metabolism induced by carbon disulfide intoxication are not due to vitamin B6 deficiency.

Animals↗
PubMed1986

Clinical pharmacology of 4-demethoxydaunorubicin (DMDR).

DMDR, a daunorubicin derivative with a higher therapeutic index and lower cardiotoxicity than either the parent drug or doxorubicin, is active when given PO in experimental animals. We studied its pharmacokinetics in ten patients receiving DMDR IV or PO or IV and PO sequentially at 10-12.5 mg/m2. DMDR and its metabolites were quantified by high-performance liquid chromatography and fluorometry. In nine patients who received DMDR IV the unchanged drug disappeared from the plasma biphasically with a mean terminal half-life of 27.0 +/- 5.5 h, an apparent volume of distribution of 63.9 +/- 12.61 kg-1, and a total clearance of 1.9 +/- 0.41 kg-1 h-1. In 24 h only 5.1% +/- 1.1% of the dose was excreted in the urine. In comparison, in 19 studies the plasma half-life of DMDR given PO was 34.8 +/- 6.7 h, 2.3% +/- 1.3% was excreted in the urine in 24 h, and the maximum plasma drug concentration was reached in about 1 h. The bioavailability of DMDR given PO was about 39% according to comparison of the areas under the plasma DMDR concentration versus time curves for the two routes, but 45% according to comparison of the 24-h cumulative urinary excretion rates. In one patient with severe liver dysfunction following oral administration, the plasma DMDR half-life was 56.8 h, more than twice the average length. By either route, the drug was quickly metabolized to one major metabolite, DMDR-ol. The plasma half-life of DMDR-ol was 72.5 +/- 24.7 h, or 35.7 +/- 7.4 when DMDR was administered IV or PO. In the plasma, DMDR-ol always exceeded DMDR in concentration. Moreover, the 24 h cumulative urinary excretion of DMDR-ol as a percentage of the dose of DMDR administered was 7.8 following IV and 7.4 following PO administration.

Daunorubicin↗
PubMed1993

Mechanisms of calcium transport across the basolateral membrane of the rabbit cortical thick ascending limb of Henle's loop.

Although net Ca2+ absorption takes place in the thick ascending limb of Henle's loop, detailed mechanisms are unknown. Because it has been reported that the Ca2+ entry step across the luminal membrane is mediated by Ca2+ channels inserted by stimulation with parathyroid hormone, we studied the mechanism of Ca2+ transport across the basolateral membrane of rabbit cortical thick ascending limb (CTAL) perfused in vitro by using microscopic fluorometry of cytosolic Ca2+ ([Ca2+]i) with fura-2. The resting [Ca2+]i in this segment was 49.8 +/- 4.5 nmol/l. Neither Na+ removal from the bathing solution nor addition of ouabain (0.1 mmol/l) to the bath increased [Ca2+]i, indicating that a Na+/Ca2+ exchanger in the basolateral membrane may not contribute in any major way to [Ca2+]i of CTAL. To confirm our technical accuracy, similar protocols were conducted in the connecting tubule, where the existence of a Na+/Ca2+ exchanger has been reported. In this segment, Na+ removal from the bath increased cell Ca2+ from 148.6 +/- 6.4 nmol/l to 647.6 +/- 132.0 nmol/l, confirming the documented fact. [Ca2+]i in the CTAL was markedly increased when 1 mmol/l NaCN was added to the bath in the absence of glucose. Calmodulin inhibitors (trifluoperazine or W-7) increased [Ca2+]i. When the bath pH was made alkaline, [Ca2+]i was also increased. This response was abolished when Ca2+ was eliminated from the bath, indicating that the Ca2+ entry across the basolateral membrane is dependent on bath pH. Increase in [Ca2+]i induced by an alkaline bath was inhibited by increased the bath K+ from 5 nmol/l to 50 mmol/l, suggesting that the Ca2+ entry system is voltage-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Neuronal death in vitro: parallelism between survivability of hippocampal neurones and sustained elevation of cytosolic Ca2+ after exposure to glutamate receptor agonist.

Hippocampal neurones isolated from rat embryos were maintained on glial monolayers in a medium containing no L-glutamate (Glu). The administration of Glu for a limited period induced a massive death (loss) of neurones. The degree of neuronal loss increased with time after exposure to Glu. The extent of neuronal loss assessed 24 h after exposure to Glu was dependent upon the concentration Glu and on the duration of the exposure. An increase in concentration of external Ca2+ during the exposure to Glu enhanced the extent of loss. By contrast, an increment in concentration of environmental Mg2+ reduced the loss. The inhibitor of spike firing, tetrodotoxin (TTX) and the suppressor of Ca2+ entry, nitrendipine, both decreased the extent of loss, when delivered prior to Glu. The toxicity of Glu became progressively more apparent with further days of culture. The cytosolic concentration of Ca2+ ([Ca2+]i) in single hippocampal neurones was monitored by microscopic fluorometry under conditions equivalent to those in the death assay. The time required for the recovery of [Ca2+]i from the level elevated by exposure to Glu to pre-stimulus levels closely paralleled the degree of neuronal loss; i.e. high doses of Glu, long periods of exposure, high concentrations of external Ca2+, low concentrations of external Mg2+, and extended days of culture all retarded [Ca2+]i recovery, while TTX and nitrendipine accelerated it. These findings show that neuronal death resulting from an extraneous excitation (excitotoxicity) can be analyzed in vitro. Furthermore, substantial support has been provided to the hypothesis that excitotoxicity has an underlying mechanism, an excess loading of Ca2+ in neuronal cytoplasm.

Animals↗
PubMed1984

Influence of pH on porphyrin production in Propionibacterium acnes.

Propionibacterium acnes was grown on Eagle's medium for 4-15 days at pH 5.3-7.2 The porphyrin production was measured both by direct fluorometry and by high pressure liquid chromatography (HPLC). The greatest concentration of porphyrins was produced at pH 6.1. Protoporphyrin was the dominant porphyrin species present in the bacteria in all samples. The relative amount of coproporphyrin was greatest at pH 6.7 after 4 days of incubation. In human skin there are local variations in the pH; therefore our findings may be of importance for porphyrin production in acne.

Chromatography, High Pressure Liquid↗
PubMed1986

Sex-related differences in the handling of fluorescent ovalbumin by the proximal tubule of the rat kidney.

Sex-dependent protein handling in the rat renal tubular system was studied both qualitatively and quantitatively using the method of direct fluorescent protein tracing. The protein tracer, fluorescent ovalbumin, was synthesized by conjugating hen ovalbumin with fluorescein isothiocyanate (FITC), and the fluorescence characteristics of fluoresceinthiocarbamyl (FTC)-ovalbumin conjugates with different degrees of labelling were studied. Heavily labelled tracer was intravenously injected into male and female rats, and both kidneys were perfused; the right kidney was then homogenized and used for quantitative fluorometric measurements, while the left kidney was perfusion fixed and prepared for fluorescence microscopy. The tubular reabsorption of fluorescent ovalbumin was studied 4 min and 10 min after the injection of different doses (1.4, 7.0 and 14.0 mg/kg body weight) of the tracer, and the tubular catabolism was investigated in animals killed 60 and 120 min after the injection. Fluorescence microscopy demonstrated that, in both sexes and regardless of the dose administered and the time after injection, specifically fluorescent protein or its degradation products was only present in the epithelial cells of the proximal tubule. With regard to sex-dependent differences in protein handling, fluorometry indicated that at 4 min (7.0 mg) and at 10 min (all doses) after injection, female animals had reabsorbed more fluorescent protein than males. With regard to the catabolic phase, both the fluorescence microscopy and the fluorometric results showed that the female rats had degraded the fluorescent tracer at a significantly higher rate than males. The results are discussed in connection with sex-dependent proteinuria in rats.

Animals↗
PubMed1983

A fast and reliable system for microcomputerized DNA cytofluorometry in tumour pathology.

A microcomputerized cytofluorometry system based on a Leitz MPV 3 cytophotometer, and intended for DNA measurements in tumour pathology is described. The system has been equipped with a reference channel for correction of excitation light instability. The importance of the adjustment of the epi-illumination for optimal performance of the reference channel is stressed, and a detailed description is provided. An apparatus variability well below 1% CV is obtained even during periods of marked instability of the arc-lamp. Software for conventional cytofluorometry with which about 200 cells can be measured in 20 min is presented. In addition a measuring technique where cells are not positioned, but are just passed through the excitation light spot is described. Preliminary results on cytocentrifuged specimens of human cancers indicate that this system is at least three times faster than conventional fluorometry. The increased speed of measurements considerably extends the possibilities to evaluate cell proliferation using static cytofluorometry. The measuring capacity of course is dependent upon the quality of the specimen. In well prepared cytocentrifuged specimens 1000 cells have been measured in 35 min.

Animals↗
PubMed1986

Reabsorption of fluorescein-isothiocyanate-labelled-ovalbumin in the kidney of normal and castrated male and female rats.

The reabsorption of ovalbumin double labelled with fluorescein isothiocyanate (FITC) in the kidneys of normal and castrated male and female rats was investigated using fluorometry and fluorescence microscopy. The animals received an intravenous injection of either 2 or 7 mg fluorescein-thiocarbamyl (FTC)-ovalbumin per kilogram bodyweight (bw) and were killed 4 or 8 min post-injection. Animals injected with unlabelled ovalbumin (7.0 mg/kg bw) served as controls. Fluorescence microscopy revealed that FTC-ovalbumin was reabsorbed exclusively in the renal proximal tubule, the highest level of reabsorption being observed in its first part. Four and eight minutes after the injection, FTC-ovalbumin was only observed in apical reabsorption vacuoles, with lysosomes exhibiting no specific fluorescence. Fluorometric determinations for the renal homogenate supernatant showed that the renal reabsorption of FTC-ovalbumin was up to 24% higher in normal females than in normal males. Castration resulted in a significant increase in renal reabsorption in male rats (up to 38%; significant), whereas a minor decrease was observed in castrated females. The renal uptake differences in normal and castrated animals are discussed in the light of the sex-hormone-dependent catabolism of lysosomal proteins in the renal proximal tubule of rats.

Animals↗
PubMed1987

Proteases in the human full-term placenta.

Aminopeptidase A, not yet defined aminopeptidases and endopeptidases, dipeptidyl peptidase I, II and IV, gamma-glutamyl transferase and oxytocinase were investigated in the normal human full-term placenta using qualitative (catalytic) cytochemistry, isoelectric focusing, immunocytochemistry and kinetic fluorometry. Aminopeptidase A could be visualized cytochemically in the smooth muscle cells of the chorionic plate, stem villi and basal plate blood vessels. Aminopeptidases were found in connective tissue fibres of the chorionic plate, villous stroma, basal plate and paraplacenta. Dipeptidyl peptidase IV was detected at the same sites as the aminopeptidases and, in addition, in amniotic epithelial cells, fibroblasts of the villous stroma, endothelium of chorionic plate and villous blood vessels as well as in the basophilic cytotrophoblast cells (x-cells) of the basal plate and paraplacenta, and it possibly also occurred in some domains of the plasma membrane of the syncytiotrophoblast and cytotrophoblast cells. The x-cells surrounded the fetus in the form of a dipeptidyl peptidase IV-positive shell at the border to the mother. The enzyme represented the first specific marker for x-cells. Dipeptidyl peptidase I and II were primarily found in Hofbauer cells (macrophages) of the villous stroma, but also in the syncytiotrophoblast, other villous stromal cells and cells of the chorionic and basal plate. gamma-Glutamyl transferase was present in some connective tissue elements of the chorionic plate. Oxytocinase and endopeptidases were not detected. Isoelectric focusing of proteases revealed different molecular forms of dipeptidyl peptidase IV in the paraplacenta and villous tree, while the aminopeptidases shared the same pattern in both regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopeptidases↗
PubMed1988

Scanning microfluorometric measurement of TRITC-phalloidin labelled F-actin. Dependence of F-actin content on density of normal and transformed cells.

A method is described for the determination of cellular F-actin content using fluorometry of TRITC-phalloidin at very high dilution. In this case no saturation of all binding sites available is reached, however the staining is highly specific and the specificity is not affected by the preparative procedure as may be the case at high concentrations of TRITC-phalloidin. The method is based on calculation of fluorescence intensity at equilibrium conditions from measurements at two different numbers of exchange of the staining solution by using Lineweaver-Burk plotting. The relative content of F-actin has been determined for three established cell lines, an amphibian cell line XTH-2 of endothelial origin, 3T3 cells and SV 40 transformed 3T3 cells. In the two non transformed lines F-actin decreases with increasing cell density starting with the onset of confluency of the culture. SV 40 transformed 3T3 cells generally contain less F-actin and do not show any significant point of change. The decrease in F-actin with increasing cell density is accompanied by a disappearance of stress fibres. SV 40 3T3 cells generally are devoid of stress fibres. The observations are discussed considering a possible involvement of F-actin in growth control.

Actins↗
PubMed1995

Dynamic functional and structural analysis of living cells: new tools for vital staining of nuclear DNA and for characterisation of cell motion.

Increasing interest has been paid to applications of fluorescence measurements to analyze physiological mechanisms in living cells. However, few studies have taken advantage of DNA quantification by fluorometry for dynamic assessment of chromatin organization as well as cell motion during the cell cycle. This approach involves both optimal conditions for DNA staining and cell tracking methods. In this context, this report describes a stoichiometric method for nuclear DNA specific staining, using the bisbenzimidazole dye Hoechst 33342 associated with verapamil, a calcium membrane channel blocker. This method makes it possible to correlate variations of nuclear DNA content with cell motion in cells that are maintained alive. Motion measurement is the second goal of this paper and it explains the snake-spline method, and the associated cell following method.

Animals↗
PubMed1992

Effects of the components of Newcastle disease virus on the structural order of lipid assemblies.

The membrane M-protein of Newcastle disease virus is localized directly beneath the lipid bilayer. Although this protein is the major constituent of the virus, its structural relationship to the lipid or to the other viral component hemagglutinin-neuraminidase, the so called HN-glycoprotein, is still unknown. The effects of either M-protein alone or both M-protein and HN-glycoprotein on the lipid assemblies in reconstituted liposomes were determined by differential polarized phase fluorometry, steady-state fluorescence anisotropy and emission lifetime measurements. It is demonstrated that the degree of rotation of fluorophores in reconstituted liposomes is restricted by the molecular packing of lipids in the bilayer and this in turn can be correlated with the structural order of the lipids in the membrane. The experimental results show that the structural order parameters calculated from the fluorescence measurements are strongly influenced by the presence of both M-protein and HN-glycoprotein in the lipid assemblies.

1,2-Dipalmitoylphosphatidylcholine↗
PubMedDate not supplied

Protein glycation and in vivo distribution of human lens fluorescence.

Glycated proteins formed by the Maillard reaction were measured by furosine determination in human normal lenses and in senile and diabetic cataracts. Furosine, an hydrolysis product of fructose-lysine adduct formed in the early stages of the Maillard reaction, was measured by high performance liquid chromatography (HPLC). Furosine levels in diabetic cataracts were found to be 3 to 4 times higher than those observed for senile cataracts. The increased glycation levels both in cortex and nucleus were related to the increase of fluorescence determined in vitro by fluorometry and in vivo by Scheimpflug photography. Lens proteins were incubated with glucose and it has been demonstrated that protein glycation occurred parallel with the increase in concentration of fluorescent chromophores that present similar characteristics as those observed in vivo. The results indicate that protein insolubilization seemed to involve preferentially glycated proteins and at least in diabetic cataracts, the process seems to be initiated in the cortical region.

Adult↗
PubMed1992

Selective effects of cyanide (100 microM) on the excitatory amino acid-induced elevation of intracellular calcium levels in neuronal culture.

The effect of low concentrations of cyanide on the excitatory amino acid-induced elevations of intracellular calcium levels ([Ca2+]i) was studied in cerebellar granule cells using ratio fluorometry with fura-2. Glutamate, kainate, N-methyl-D-aspartate (NMDA), quisqualate (50 microM, each) and membrane depolarization by 40 mM KCl caused elevations of [Ca2+]i which were 10-, 10-, 3-, 2.3-, 10-fold over baseline levels, respectively. Cyanide, 100 microM, greatly augmented the increases in [Ca2+]i induced by glutamate, kainate and NMDA but not those induced by quisqualate or KCl. In the absence of these excitatory amino acids, cyanide had no significant effect in concentrations up to 400 microM. Elevations of [Ca2+]i induced by quisqualate and KCl were not significantly augmented by higher concentrations of cyanide (400 microM). Selective antagonists could block the effect of cyanide+the respective agonist; however, the calcium channel blockers, lanthanum and diltiazem lowered both NMDA- and kainate-induced elevations of [Ca2+]i, yet neither blocked increases in calcium when 100 microM cyanide was added. Collectively, these data support an interaction of cyanide with the excitatory amino acid receptor.

Amino Acids↗
PubMed1983

Diagnostic value of serum bile acids and routine liver function tests in hepatobiliary diseases. Sensitivity, specificity, and predictive value.

Total serum bile acids measured by enzymatic fluorometry and routine liver function tests were determined in a large population including 97 healthy subjects, 138 patients free of hepatobiliary diseases but affected by other diseases, and 344 patients with mild or severe hepatobiliary diseases. In order to define the diagnostic value and some operational characteristics of serum bile acids, sensitivity, specificity, and several predictive value tables for increasing cutoff levels of serum bile acids were calculated by means of a computer program. Serum bile acids and aspartate aminotransferase were found to be similar in sensitivity, specificity, and predictive value. Serum aspartate aminotransferase was found to be more suitable than serum bile acids in detecting mild hepatobiliary diseases, whereas serum bile acids were more sensitive than routine liver tests in the evaluation of severe hepatobiliary diseases. In view of its ability to detect severe hepatobiliary diseases, serum bile acids test may play a decisive role in clinical practice (eg, decision to perform a liver biopsy).

Adolescent↗
PubMed1986

Subcellular fractionation and subcellular localization of aminopeptidase N in the rabbit enterocytes.

A fast and easy procedure is proposed for preparing concomitantly from the same sample of intestinal mucosa of A+ rabbits, four fractions high enriched in the brush-border and basolateral plasma membrane domains, rough endoplasmic reticulum, and smooth endoplasmic reticulum plus Golgi apparatus membranes, respectively. This is the first time the technique of flow fluorometry has been applied to characterize the brush-border and basolateral membrane fractions using polyclonal or monoclonal antibodies against antigens common to or specific for these two plasma membrane domains. This technique definitely proves the presence of aminopeptidase in at least 60% of the basolateral membrane vesicles, where its level is about 4.5% of that in the brush-border membrane vesicles. The endoglycosidase H-sensitive intermediate of glycosylation of aminopeptidase N in the steady state is accumulated in both the rough and smooth endoplasmic reticulum membranes. Although the rough membrane is more extensive it contains only about 40% of this transient form.

Aminopeptidases↗