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PubMed2002

Simultaneous determination of Aloe-emodin and Rhein by synchronous fluorescence spectroscopy.

A simple sensitive and quick assay to simultaneously determine Aloe-emodin (AE) and Rhein (RH) has been described based on their natural fluorescence. Due to their similar molecule structures, it is difficult to analysis and determine their contents by conventional fluorometry. Overlapping of fluorescence spectra was resolved by using synchronous fluorometry. The synchronous spectrum, maintaining a constant difference of Deltalambda=25 nm between the emission and excitation wavelengths, has been selected as optimum to perform the determination. This method was applied to the simultaneous determination of AE and RH in simulated mixtures. Analytical recoveries range from 94.5 to 105.5% for AE and from 98.7 to 107.5% for RH. At the same time, the content of AE abstracted from Cassitora L. was successfully analyzed. The results were satisfactory.

Anthraquinones↗
PubMed1992

Enzymatically amplified time-resolved fluorescence immunoassay with terbium chelates.

We report an ultrasensitive, enzymatically amplified, time-resolved fluorescence immunoassay with a terbium chelate as the detectable moiety. In this immunoassay, the primary label is the enzyme alkaline phosphatase (ALP). ALP cleaves phosphate out of a fluorogenic substrate, 5-fluorosalicyl phosphate, to produce 5-fluorosalicylic acid (FSA). 5-Fluorosalicylic acid can then form a highly fluorescent ternary complex of the form FSA-Tb(3+)-EDTA, which can be quantified by measuring the Tb3+ fluorescence in a time-resolved mode. In this assay, exceptional sensitivity is achieved because of the enzymatic amplification introduced by ALP and the quantification by laser-induced microsecond time-resolved fluorometry. Time-resolved fluorometry is applicable because of the long fluorescence lifetime of the Tb3+ complexes. It is shown that in a model AFP assay 10(6) or 1.5 x 10(5) molecules can be detected (final assay volume, 100 microL) by using monoclonal or polyclonal detection antibodies, respectively. The assay demonstrates excellent precision (approximately 4%), and it seems to be highly suited for automated, sensitive, and rapid immunoassays.

Alkaline Phosphatase↗
PubMed2002

Comparative study of three different methods for the determination of aflatoxins in tahini.

Aflatoxins spiked at three different levels (6.5, 13.0, and 19.5 microg/kg) in tahini, a sesame butter, were analyzed by using three different methods: high-performance liquid chromatography (HPLC), fluorometry, and enzyme-linked immunosorbent assay (ELISA). An immunoaffinity column was used for cleanup and purification of extracts prior to detection by HPLC and fluorometry. All methods were statistically evaluated for accuracy, precision, and simple correlations. Additionally, 14 tahini samples randomly obtained from Turkish retail markets were analyzed using an immunoaffinity column cleanup procedure coupled with the HPLC detection method. The fluorometric determination method involving an immunoaffinity column cleanup step was found to be highly correlated with the HPLC method (r = 0.978). Both methods were found to be effective due to their high recoveries and low variance for the prediction of total aflatoxin contamination in tahini samples. The ELISA method, due to its high variation in replicates, was found to be applicable only as a screening method. The survey study demonstrated the need for control of aflatoxin contamination of foodstuffs involving sesame seeds as an ingredient.

Aflatoxins↗
PubMed1999

Lens autofluorescence and light scatter in relation to the lens opacities classification system, LOCS III.

PURPOSE: To compare values of the human lens autofluorescence and back light scatter measurements with the improved Lens Opacities Classification System, LOCS III. METHODS: We measured autofluorescence and back light scatter of the lens from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The retroillumination and slit-lamp photographs of the lenses were graded according to LOCS III by the Center for Ophthalmic Research in Boston. Lens fluorometry was carried out with a previously described technique using blue-green (495 nm/520 nm) autofluorescence range. Interzeag Lens Opacity Meter 701 was used for light scatter measurements. RESULTS: LOCS III nuclear opalescence and color grades were statistically significantly correlated with lens autofluorescence as well as with light scatter values. The lens transmission index of autofluorescence measurements showed the highest correlation with the nuclear color (r = -0.71; p < 0.0001) and the light scatter value with nuclear opalescence (r = 0.64; p < 0.0001). There was no correlation between autofluorescence measurements and LOCS III grades of cortical or posterior subcapsular cataract. A weak relation could be found between the grades of cortical cataract and light scatter values. CONCLUSIONS: The lens fluorometry provides a practical clinical technique to evaluate the yellow coloration and opalescence of the human lens nucleus. It may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.

Aged↗
PubMed1999

The sulfate moieties of glycosaminoglycans are critical for the enhancement of beta-amyloid protein fibril formation.

Our previous studies have demonstrated that perlecan and perlecan-derived glycosaminoglycans (GAGs) not only bind beta-amyloid protein (Abeta) 1-40 and 1-42, but are also potent enhancers of Abeta fibril formation and stabilize amyloid fibrils once formed. However, it was not determined which moieties in perlecan heparan sulfate GAG chains may be responsible for the observed effects and whether other GAGs were also capable of a similar enhancement of Abeta fibril formation as observed with perlecan GAGs. In the present study, thioflavin T fluorometry (over a 1-week period) was used to extend our previous studies and to test the hypothesis that the sulfate moiety is critical for the enhancing effects of heparin/heparan sulfate GAGs on Abeta 1-40 fibrillogenesis. This hypothesis was confirmed when removal of all sulfates from heparin (i.e., completely desulfated N-acetylated heparin) led to a complete loss in the enhancement of Abeta fibrillogenesis as demonstrated in both thioflavin T fluorometry and Congo red staining studies. On the other hand, removal of O-sulfate from heparin (i.e., completely desulfated N-sulfated heparin), and to a lesser extent N-sulfate (i.e., N-desulfated N-acetylated heparin), resulted in only a partial loss of the enhancement of Abeta 1-40 fibril formation. These studies indicate that the sulfate moieties of GAGs are critical for enhancement of Abeta amyloid fibril formation. In addition, other sulfated molecules such as chondroitin-4-sulfate, dermatan sulfate, dextran sulfate, and pentosan polysulfate all significantly enhanced (greater than twofold by 3 days) Abeta amyloid fibril formation. These latter findings indicate that deposition and accumulation of other GAGs at sites of Abeta amyloid deposition in Alzheimer's disease brain may also participate in the enhancement of Abeta amyloidosis.

Alzheimer Disease↗
PubMed1999

Hemodynamics and mitochondrial energy metabolism in right heart hypertrophy after acute hypoxic stress.

Excessive right heart hypertrophy was investigated under additional acute hypoxic stress to find out a possible contribution of mitochondrial dysfunction to sudden heart failure. Severe right heart hypertrophy in rats was induced by exposure to hypobaric pressure (46,663 Pa) for 4 weeks. Heart rate, isovolumic pressure and coronary flow were determined in the Langendorff mode of perfusion. After normoxia, the hearts were subdued to acute hypoxia/reoxygenation. Mitochondrial membrane potential was measured at the heart surface by fluorometry using 2-(dimethylaminostyryl)-l-ethylpyridinium iodide (DASPEI). At the end of each experiment mitochondria were isolated and ATP synthesis, ATPase, as well as creatine kinase activity were determined. Compared to normal hearts the heart rate is decreased in the hypertrophied group whereas right ventricular systolic and (end)diastolic pressure (adjusted to isovolumetric maxima) are increased. Coronary flow is decreased. Cytosolic creatine phosphate ATP levels and ATP/ADP ratios are significantly (p < 0.01) decreased. Furthermore, ATP synthesis and creatine kinase activities are diminished. At high ADP, respiration is loosely coupled or partially uncoupled. Acute hypoxia is particularly deleterious to hypertrophied hearts: Mitochondrial membrane potential as measured by heart surface fluorometry decreases extensively and is only very incompletely restored during reoxygenation. Rate-pressure product decreases precipitously and is restored during reoxygenation only to a very low extent. The results indicate an insufficient energy metabolism of mitochondria during acute hypoxia/reoxygenation which adds to the earlier described shifted isozyme pattern of myosin and decreased activities of myosin and sarcoreticular Ca2+ ATPase, leading to myocardial failure in right heart hypertrophy.

Adenosine Triphosphatases↗
PubMedDate not supplied

Bioadhesive fluorescent microspheres as visible carriers for local delivery of drugs. I: preparation and characterization of insulin-loaded PCEFB/PLGA microspheres.

Inherently fluorescent microspheres composed of a fluorescent polyanhydride, poly(p-(carboxyethylformamido) benzoic anhydride) (PCEFB), and poly(lactide-co-glycolide) (PLGA) were prepared using the water-in-oil-in-water (w/o/w) emulsion solvent evaporation technique. The effect of the PCEFB/PLGA feed ratio and composition of the oil phase on insulin entrapment and microsphere diameter was evaluated. It was found that the insulin entrapment efficiency increased with PCEFB content and acetone per cent in the oil phase. Microsphere diameter decreased as acetone was added into the oil phase. The blend of microspheres were further characterized by GPC, IR, fluorometry and SEM. Although slight degradation of PCEFB during the fabrication process was revealed by GPC and IR, PCEFB/PLGA microspheres could still be clearly visualized by either CLSM or fluorescent microscopy, which makes it possible to directly detect the microspheres by fluorometry in vivo without the need of labelling with fluorescent dyes. The surface of PCEFB/PLGA (1:2) microspheres was smooth, while PCEFB/PLGA (2:1) microspheres were observed with rough and uneven surfaces. Sustained release of insulin from the microspheres could be achieved for approximately 4 days.

Adhesiveness↗
PubMed2006

Lens fluorescence in relation to glucose tolerance and genetic predisposition to type 2 diabetes mellitus in a population-based study.

PURPOSE: The fluorescence of the lens has the characteristics of a life-long cumulative index of glycemia, and it is elevated in patients with diabetes in proportion to the duration of diabetes and the level of glycemia. Consequently, lens fluorometry should be capable of providing an estimate of prediagnostic disease duration when patients are diagnosed with type 2 diabetes. Among euglycemic subjects, first-degree relatives of patients with type 2 diabetes tend to have higher glycemia levels than subjects who are unrelated to diabetes patients. They should therefore also have the higher lens fluorescence values. METHODS: The study comprised 218 Caucasian subjects in self-reported good health aged 30-88 years who were recruited from population-based studies to represent approximately equal proportions of different type 2 diabetes family history characteristics: no diabetic relative, first-degree offspring, second-degree offspring, not first-degree offspring but possibly second-degree offspring, or uncertain family history. Characterization of subjects included oral glucose tolerance testing and lens fluorometry. RESULTS: Type 2 diabetes was diagnosed in 10 subjects (4.6% of the population) and impaired glucose tolerance in 12 subjects (5.5%). Regression analysis indicated a prediagnostic duration of type 2 diabetes of 2.7 years versus 0.1 years for impaired glucose tolerance. Neither group demonstrated significantly increased lens fluorescence compared with euglycemic subjects. Being a first-degree relative of a patient with type 2 diabetes was associated with higher lens fluorescence than having no relative with diabetes (p = 0.02). CONCLUSIONS: Population screening by fasting blood glucose measurement can advance the diagnosis and initiation of treatment of type 2 diabetes mellitus by nearly a decade, compared with previous studies of patients diagnosed in routine clinical practice. In addition to higher than normal glycemia, euglycemic subjects who are offspring of patients with type 2 diabetes also have both elevated lens fluorescence and elevated glycemia. Fasting blood glucose measurement remains the method of choice for type 2 diabetes screening.

Adult↗
PubMed1985

Hydrolysis of substance P and its analogs by angiotensin-converting enzyme from rat lung. Characterization of endopeptidase activity of the enzyme.

Hydrolysis of substance P and nine kinds of substance P analogs by angiotensin-converting enzyme highly purified from rat lung was examined by using amino-group fluorometry and high-performance liquid chromatography. The enzyme hydrolyzed substance P and several analogs, notwithstanding that they did not contain free C-terminal residues. The analyses of cleavage products separated by high-performance liquid chromatography indicated that the enzyme hydrolyzed substance P and its analogs mainly at the bond between Phe8-Gly9 and also at another bond, possibly between Gly9-Leu10, to a lesser extent by an endopeptidase action, followed by successive release of dipeptides by a dipeptidyl carboxypeptidase action. The analogs that had D-amino acid residues substituted at the presumed cleavage sites were scarcely hydrolyzed. It was further found that (Pyr6)-fragment (6-11) was hydrolyzed by the enzyme more efficiently than the other fragment-type analogs and was cleaved at a single bond by the endopeptidase activity of the enzyme. Therefore, this fragment was used as a substrate in order to characterized the endopeptidase activity of the enzyme by employing fluorometry. The activity was dependent on chloride ion, and was inhibited by captopril, MK-421, and EDTA. Thus, the endopeptidase activity of the enzyme showed properties similar to those of the dipeptidyl carboxypeptidase activity of the enzyme.

Amino Acid Sequence↗
PubMed1977

Simultaneous determination of furosemide and two of its possible metabolites in biological fluids.

By the means of thin-layer chromatography (TLC) prior to fluorometry it was possible to determine furosemide (F) in plasma and urine with improved specificity. Antranilic acid (A) and 4-chlor-5-sulphamoyl-antranilic acid (CSA) could be determined simultaneously with F in plasma. In urine, only F and A could be determined quantitatively by this method. The sensitivity is 0.1 microgram/ml for F and 0.15-0.20 microgram/ml for A and CSA. By means of TLC prior to fluorometry the blank value for F was reduced in normal subjects and in different groups of patients, and its diurnal variation was eliminated. The average values of the plasma concentrations of F after the intravenous injection of 40 mg into 12 normal subjects were at all times found to be lower by the TLC method than by the fluorometric method without TLC. A higher plasma clearance and a lower volume of distribution were found for F when the values obtained by the TLC method were used for the calculation.

Chromatography, Thin Layer↗
PubMed1996

Vitamin E decreases urine lipid peroxidation products in young healthy human volunteers under normal conditions.

An experimental study on the effects of supplementation with antioxidant vitamins on urine lipid peroxidation products was performed in 21 young healthy men. The subjects ingested placebo, 1 g of vitamin C, or 100 mg of vitamin E per day just after the midday meal during 30 days. Urine samples were obtained 0, 15 and 30 days after the beginning of the study. These samples were analyzed by spectrophotometry or fluorometry after reaction with thiobarbituric acid. Prescan fluorometric studies of the thiobarbituric acid reactive substances in both malondialdehyde standards and urine samples indicated 503 nm and 548 nm as optimum excitation and emission wavelengths. The fluorescence measurements proved to be superior both in terms of selectivity and capacity of detection of antioxidant effects in relation to spectrophotometry. Identical emission peaks were obtained with malondialdehyde standards and urine samples, showing the specificity of the fluorometric method. When measured by fluorometry, the urine of the subjects supplemented with vitamin E showed significantly and progressively smaller lipid peroxidation products as the time of supplementation increased, reaching a 27% decrease at the end of the longitudinal trial. The results indicate the usefulness of the fluorescent measurement of urine thiobarbituric acid reactive substances to easily and rapidly detect variations in whole body oxidative stress in humans. They also show the capacity of safe vitamin E dietary doses to decrease endogenous oxidative stress in healthy humans routinely performing their normal activities.

Adult↗
PubMed1979

Rapid assay for determination of trimethoprim and sulfamethoxazole levels in serum by spectrofluorometry.

A rapid spectrofluorometric method for determining the levels of both trimethoprim and sulfamethoxazole from the same specimen of serum is described. The method involves stepwise extraction of the specimen first with chloroform at an alkaline pH (pH 9.0) for trimethoprim followed by n-butyl chloride at an acidic pH (pH 2.0) for sulfamethoxazole. To quantitate trimethoprim, the chloroform layer was subjected to fluorometry by exciting the specimen at 295 nm and measuring the relative intensity at 330 nm. To determine sulfamethoxazole levels, the n-butyl chloride layer was subjected to fluorometry by exciting the specimen at 285 nm and measuring the relative intensity at 330 nm. Relative intensities were linear (r greater than 0.99) over the concentration ranges of 0.5 to 40 microgram/ml for trimethoprim and 1 to 400 microgram/ml for sulfamethoxazole. Values obtained by this spectrofluorometric procedure were in excellent agreement with those obtained by a conventional fluorometric assay for trimethoprim and a colorimetric assay for sulfamethoxazole. Elevated levels of endogenous metabolic products and numerous other drugs, including a number of antimicrobial agents, did not interfere with the method. Although salicylates interfere with the determination of sulfamethoxazole, an appropriate correction can be made. This method can also be used to determine the drug levels in cerebrospinal fluid.

Humans↗
PubMed1991

In vivo mechanisms of myocardial functional stability during physiological interventions.

Metabolic regulatory mechanisms are designed to maintain stable myocardial function during extremes in physiological insult; they can now be studied in vivo and may provide insight into mechanisms of altered myocardial functional decompensation during disease processes. To determine mechanisms of myocardial stability during hypoxia and acute pressure loading, creatine kinase (CK) kinetics (forward rate constant, Kf, and flux of phosphocreatine, PCr, to adenosine triphosphate, ATP), and nicotinamide adenine dinucleotide (NADH) redox state were determined with 31P nuclear magnetic resonance (NMR) and NADH fluorometry, respectively, and correlated with heart work (heart rate x systolic blood pressure, HR x SBP), cardiac output (CO) and O2 consumption (MVO2) in 15 anesthetized open chest dogs. Hypoxia (PaO2 of 30-35 mm Hg) was produced in 6 dogs with an inspired O2/N2 of 200/3,000. Cardiac loading was produced in 9 dogs by administration of norepinephrine (NE, 1 micrograms/kg/min). Each dog acted as its own control. Baseline NADH fluorometry, 31P-NMR saturation transfer and cardiac function measurements were performed simultaneously in each dog, after which the experimental interventions were made. Similar increases in HR x SBP, CO, and MVO2 which occurred during both interventions were associated with different bioenergetic responses. During NE infusion, the Kf of CK increased from control; during hypoxia, the Kf decreased from control (p less than 0.05). Flux of PCr----ATP was significantly lower during hypoxia than during NE infusion (p less than 0.05). PCr was decreased significantly during NE infusion (p less than 0.05). In addition, NADH redox state increased (from baseline of 100%) during hypoxia (140 +/- 10%) and decreased during NE infusion (78 +/- 6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1985

Pharmacokinetics of spironolactone and potassium canrenoate in humans.

Plasma concentrations and urinary excretion of canrenone (III), canrenoic acid (IV) and canrenoic acid glucuronide (V) were determined by means of high performance liquid chromatography (HPLC) and fluorometry after oral administration of spironolactone (I) and potassium canrenoate (II) to human subjects. Comparison of both assays for III in plasma as well as in urine after administration of I showed marked differences. Plasma concentrations of III were significantly higher after administration of II than I, Cmax and AUC from II being 3--5 times larger than those from I by means of HPLC assay, while the fluorometrically determined values for III in plasma after administration of I and II did not differ as much from each other. On the other hand, in contrast to plasma, the amount of III excreted in urine after administration of I was much larger than that after II, i.e. 3--4 times greater by means of HPLC and over 10 times greater by means of fluorometry. These results strongly suggest that precursors of III are formed which have a higher renal clearance than that for III alone after oral administration of I. Considering the relative biological potency ratio of I and II, it is presumed that their pharmacological activities may relate to the urinary excretion of III. Plasma concentrations of IV were definitely higher after administration of II compared to those after I. Canrenoic acid (IV) was excreted mainly as glucuronide (V) in urine.

Adult↗
PubMed1994

[Micromethods for the determination of metabolic characteristics in individual nephron segments].

Since a single nephron is a functional unit of the kidney, individual microdissected segments from the nephron would be ideal tissue samples for investigations on renal pharmacology. Several micromethods have enabled researchers to analyze the biochemical and pharmacological characteristics of these nephron segments. Miniaturized cuvettes containing microliter volumes of samples can be applied for general procedures of photometry like Lowry's protein determination. Fluorometry becomes a more sensitive method when enzymatic cycling systems of NAD/NADH or NADP/NADPH are combined, which have been used for assays of enzyme activities or substrate contents in minute biological samples having tissue proteins less than 1 microgram. The microchemiluminescence procedure has been successfully utilized for cellular ATP content or oxygen radical generation. Radioimmunoassay can be used to determine endogenous components such as cyclic nucleotides, eicosanoids, etc. Continuous gradient polyacrylamide microgels prepared in 5- to 10-microliters capillaries have made it possible to quantify the intranephron distribution of cytochrome P-450, xanthine oxidase and superoxide dismutase. As an example of the modern techniques, microscopic fluorometry using Fura-2AM has been established to identify agonist-induced cytosolic free calcium transients.

Ammonia↗
PubMed2006

Metabolic changes in mesenchymal stem cells in osteogenic medium measured by autofluorescence spectroscopy.

The purpose of this study was to measure metabolic changes in mesenchymal stem cells (MSCs) placed in osteogenic medium by autofluorescence spectroscopy. MSCs were plated in stem cell-supporting or osteogenic medium and imaged. Shift from the basic growth environment to the inductive osteogenic environment was confirmed by reverse transcription-polymerase chain reaction. Reduced pyridine nucleotides were detected by exciting near 366 nm and measuring fluorescence at 450 nm, and oxidized flavoproteins were detected by exciting at 460 nm and measuring fluorescence at 540 nm. The ratio of these fluorescence measurements, reduction-oxidation (redox) fluorometry, is a noninvasive measure of the cellular metabolic state. The detected pyridine nucleotide to flavoprotein ratio decreased upon transitioning from the stem cell to the differentiated state, as well as with increasing cell density and cell-cell contact. MSC metabolism increased upon placement in differentiating medium and with increasing cell density and contact. Redox fluorometry is a feasible, noninvasive technique for distinguishing MSCs from further differentiated cells.

Animals↗
PubMed2001

Diabetic macular edema: passive and active transport of fluorescein through the blood-retina barrier.

PURPOSE: To investigate the passive bidirectional and active outward transport of fluorescein through the blood-retina barrier (BRB) in diabetic patients with clinically significant macular edema and in healthy controls. METHODS: The passive and active transport of fluorescein through the BRB was quantitated by vitreous fluorometry. A previously developed method was used to model passive transport. A new simulation model was developed and evaluated for estimation of active transport. The study included 10 eyes of 5 healthy controls and 31 eyes of 20 diabetic patients with clinically significant diabetic macular edema (CSME) in at least one eye, totalling 25 eyes with CSME. RESULTS: Passive permeability of fluorescein was increased by a factor of 12 in eyes with edema compared to healthy controls (edema, 23.7 nm/sec; healthy subjects, 1.9 nm/sec, P < 0.01), whereas the active transport was doubled (edema, 84.1 nm/sec; healthy subjects, 43.5 nm/sec, P < 0.01). Unlike active transport, passive permeability was related to the degree of retinopathy, in that eyes with severe non-proliferative diabetic retinopathy had a passive permeability that was significantly increased compared to moderate retinopathy (32.1 nm/sec and 14.6 nm/sec, respectively, P: < 0.05). The passive movement quantitated with vitreous fluorometry was larger for diffuse and mixed leakage compared to focal (P = 0.07). CONCLUSIONS: Insofar as the movement of fluorescein can be taken as a probe for the movement of electrolytes and water, the pathogenesis of diabetic macular edema seems to involve a disruption of the BRB, presumably its inner component. The active resorptive functions of the blood-retina barrier appear to be compensatorily increased to counteract edema formation, although the increase is too small to prevent edema in the face of severe leakage through the blood-retina barrier.

Adult↗
PubMed1975

Chromatographic separation of autofluorescent and quenching substances from the hydrocarbon in tissue.

In spite of the recent progress in fluorometry, the measurement of carcinogenic hydrocarbons in tissue has been carried out with insufficient accuracy because of the presence of substances in the tissue interfering with fluorometry. Such substances, autofluorescent and quenching substances, were removed from ethanol extracts of the tissue by Sephadex LH-20 column chromatography. By elution of the column with ethanol, the interfering substances appeared in fractions of the void volume for 3-methylcholanthrene chromatography. In addition, the excitation wavelength for autofluorescent substances was found to be far from that for 3-methylcholanthrene, for which the excitation was at 300 nm and the luminescence was measured at 400 nm. Chromatographic separation of 3-methylcholanthrene and its metabolites in the bile and veces obtained from rats was done and only one peak consisting of conjugated metabolites was found on the chromatogram of the bile, though three peaks consisting respectively of the parent hydrocarbon with some metabolites, nonconjugated metabolites, and conjugated metabolites were observed in the feces. Total amounts of 3-methylcholanthrene and its metabolites, though the majority of the fluorescent substances were the parent hydrocarbon, in the lung and other organs were measured at various intervals after an intrabronchial application of 1 or 5 mg of 3-methylcholanthrene in Freund's incomplete adjuvant to rats. Preservation of the hydrocarbons in the treated lung was confirmed and this was considered to take part in the enhanced occurrence of epidermoid tumors in the lung.

Administration, Intranasal↗