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PubMed1983

[Comparative study of laminarinases from marine mollusks using differential UV-spectrophotometry].

A comparative study of tryptophane residues in endo-beta-1.3-glucanases from marine molluscs was carried out by UV-differential spectrophotometry and chemical modification with N-bromosuccinimide methods. The number of tryptophane and tyrosine residues exposed and accessible to the solvent was determined, using a solvent perturbation technique with 20% ethylene glycol. The alteration in the accessibility of these residues in 8 M urea and in the presence of the reaction substrate was shown. The tryptophane residues of endo-beta-1.3-glucanases were found to participate in the enzyme-substrate interaction. The interaction between endo-beta-1.3-glucanases and the substrate, laminarine, as well as between the substrate analogs and inhibitors--cellobiose and glucone-1,5-lactone, was investigated.

Animals↗
PubMed1983

Direct determination of sodium and potassium in blood serum by flow injection and atomic absorption spectrophotometry.

A simple and reliable method for the measurement of sodium and potassium in blood serum without any sample dilution by using flow injection and atomic absorption spectrophotometry is described. A sample throughout of 100 measurements per hour is possible. Matrix problems have not been encountered. The coefficient of variation for within-run determinations is about 1,14 and 2,36% for sodium and potassium, respectively, in serum samples (n = 10). The method is easily adaptable to pediatric research, because of the low required sample volume of 5 microliter.

Blood Specimen Collection↗
PubMed1984

Direct spectrophotometry of serum hemoglobin: an Allen correction compared with a three-wavelength polychromatic analysis.

An Allen correction and a polychromatic analysis are about equally effective in minimizing effects of interference by bilirubin and triglyceride turbidity in the direct spectrophotometry of serum hemoglobin: interference from bilirubin is nearly eliminated, that from turbidity substantially decreased. The limit of detectability of hemoglobin is 8 mg/L in the presence of a moderate concentration of bilirubin. A change in hemoglobin concentration as small as 16 mg/L can be detected in serum having a concentration near the upper limit of the reference interval, i.e., at the medical decision level. The polychromatic formula gives concentration estimates approximately 5% greater than those of the Allen correction. The formula for the Allen correction is hemoglobin (mg/L) = 1.68 mA415 - 0.84 mA380 - 0.84 mA450 . That for the polychromatic analysis is hemoglobin (mg/L) = 1.65 mA415 - 0.93 mA380 - 0.73 mA470 .

Bilirubin↗
PubMed1984

Glucocorticoids directly affect spectrophotometry of bilirubin in amniotic fluid.

Dexamethasone or prednisolone, added in vitro to bilirubin-containing amniotic fluid, produces a time-dependent decrease in the 450-nm absorbance of the pigment. Neither the chemical determination of bilirubin in amniotic fluid nor the lecithin/sphingomyelin ratio as determined by thin-layer chromatography is affected by these glucocorticoids. The effect probably is not a result of displacement of bilirubin from its binding sites on albumin, because the absorbance of a solution of crystalline bilirubin at 450 nm is unaffected by added bovine serum albumin. Light scattering of amniotic fluid increases slightly when dexamethasone is added, whether or not low concentrations of bilirubin (less than 1.6 mumol/L) are present. Thus the effect on absorbance evidently is not ascribable to supersaturation and formation of a colloidal sol of bilirubin particles. This direct interference of glucocorticoids with the spectrophotometry of bilirubin in amniotic fluid prompts cautious interpretation of such data as an index to the severity of hemolytic disease of the fetus, specifically in cases of Rhesus-isoimmunization that are being treated with glucocorticoids.

Amniotic Fluid↗
PubMed1983

Optimized atomic absorption spectrophotometry of zinc in cerebrospinal fluid.

This method for direct determination of Zn in cerebrospinal fluid (CSF) involves flame atomic absorption spectrophotometry with a pulse nebulizer technique. Standard solutions of Zn in 150 mmol/L NaCl were used. We could account for 88% of added standard with the method in individual samples from 10 patients and in pooled CSF. The method is acceptably precise, CVs in pooled CSF ranging from 4 to 12%. The mean CSF-Zn concentration for nine healthy men was 0.18 (SD 0.04) mumol/L and for nine healthy women 0.15 (SD 0.03) mumol/L, a statistically insignificant difference. These values are lower than those in previous reports, which may have been the result of contamination problems, nonatomic absorption, or nonstandardized sampling. In the healthy volunteers, the CSF-Zn concentration was positively correlated with serum-Zn, CSF-protein, and CSF-albumin concentrations, as well as with the CSF/serum ratio for albumin.

Adult↗
PubMed1983

Improved determination of aluminum in serum by electrothermal atomic absorption spectrophotometry.

This method for determining aluminum in human serum involves electrothermal atomic absorption spectrophotometry. A longer drying time allows less pre-dilution of the sample, and the method also includes a flush cycle after atomization. Standard-addition methodology is used to eliminate matrix effects and the need for a standard curve. We used this method on serum from 50 normal persons and from 34 patients with chronic renal failure who were on long-term intermittent hemodialysis. The mean normal serum aluminum concentration was 6.1 micrograms/L (CV 2.7%), and values for the patients ranged from 13 to 475 micrograms/L.

Aluminum↗
PubMed1983

Phase-lifetime spectrophotometry of membranes from ion flux mutants of Halobacterium halobium.

Phase-lifetime spectrophotometry has been used to study the rate processes associated with intermediates in the photocycling pigments in membrane vesicles of mutant strains of Halobacterium halobium. Vesicles deficient in bacteriorhodopsin, but containing halorhodopsin, were monitored with light at 490 nm. Two relaxation processes, with kinetic parameters largely independent of pH over the range 6.2-7.8, were found to be associated with halorhodopsin photocycling in 4 M NaCl, 10 mM buffer at 23 degrees C. The average relaxation times are 0.94 and 11.4 ms. When vesicles deficient in both bacteriorhodopsin and halorhodopsin were monitored at 370 nm, a single relaxation process with an average relaxation time of 168 ms was detected. This process is independent of pH over the range 4.7-8.8. Examination of vesicles from ion flux mutants showed this slow process to be unrelated to halorhodopsin content and to derive from another photoreactive retinal pigment, possibly the recently described slow cycling pigment s-rhodopsin.

Bacteriorhodopsins↗
PubMed1978

[Estimation of aluminium in biological fluids by atomic absorption spectrophotometry in a graphite oven (author's transl)].

The possibilities of use of a graphite oven type HGA 74 (Perkin Elmer) for the estimation of aluminium in biological fluids by atomic absorption spectrophotometry are described, with a special study of the stages of drying, mineralisation, atomisation, flow of inert gas, requirement for correction of non-specific absorption, etc. Under fixed experimental conditions, the limit of sensitivity (absorption 1%) was 2.28.10.(-11) grams and the linearity was good up to 100 microgram/l. This method of analysis by direct treatment of the samples required only small volumes of the latter and reduces the risk of contamination.

Aluminum↗
PubMed1978

Determination of aluminum in biological samples by atomic absorption spectrophotometry with a graphite furnace.

Aluminum, generally considered non-essential and non-toxic, may accumulate in toxic amounts in the brain in cases of chronic renal failure. We describe a procedure for its analysis in biological fluids by atomic absorption spectrophotometry with a graphite furnace. No sample preparation is required and the procedure is sensitive at the appropriate concentrations. A sample of serum or urine is pipetted into the interior of the graphite tube, where it is sequentially dried, charred, and atomized. Precautions for sample handling are discussed and instrument settings are defined. Precision and accuracy of the method are evaluated, as are the effects of salts, protein content of serum, and specific gravity of urine. Serum of 23 persons who were not consuming aluminum-containing antacids contained 28 +/- 9 (SD) microgram of Al per liter (1.02 +/- 0.33 mumol/liter).

Aluminum↗
PubMed1982

[Direct determination of phenylalanine in serum by derivative spectrophotometry (author's transl)].

A simple and precise method is described for the determination of phenylalanine in serum or plasma, using derivative spectrophotometry. After the removal of protein and uric acid, 100 microliters serum or plasma are analysed directly for phenylalanine. The magnitude of the difference between the peak minimum at 254 nm and the peak maximum at 257 nm of the derivative spectrum (2nd derivative of the absorption spectrum) is directly proportional to the phenylalanine content. The precision was 2.1-10.3%, depending on the concentration of phenylalanine. Recovery was between 97.1 and 101.1%. Sensitivity was 5 mg/l serum. The method was compared with a column chromatographic determination of phenylalanine.

Humans↗
PubMed1982

Flameless atomic absorption spectrophotometry of selenium in whole blood.

In this method of analysis for selenium in whole blood by flameless atomic absorption spectrophotometry, 1 mL of sample is first digested with perchloric and nitric acids. After reduction and neutralization, the sample is reacted with 2,3-diaminonaphthalene, and the product is extracted into toluene. Twenty microliters of the extract is injected into the graphite furnace of a flameless atomic absorption spectrophotometer, along with 20 microliters of a 1.0 g/L cupric nitrate solution. Blood-based standards are used to establish the standard curve. The amount of selenium required to give an absorbance of 0.0044 is 5.3 micrograms/L. Precision is good, recovery excellent. The extract is stable for 24 h.

Female↗
PubMed1982

Gastric mucosal hemodynamics after thermal or head injury. A clinical application of reflectance spectrophotometry.

In order to elucidate the role of mucosal blood flow in stress ulceration in critically ill patients with thermal or head injury, we applied reflectance spectrophotometry to the human gastric mucosa. During gastrofiberscopy, the spectra of the corpus and antral gastric mucosa were taken using a flexible coaxial optic bundle and a computer-equipped spectrophotometer. The subjects were 27 patients with thermal or head injury, and they were compared with 8 young healthy volunteers and 9 age-matched patients who had GI symptoms but showed no gastric lesion endoscopically. In 8 patients whose gastric mucosal blood volume at the time of admission decreased to about 27% of the level of young healthy volunteers or 36% of that of age-matched controls, the acute gastric mucosal lesions appeared in the corpus mucosa mostly within a few days after the measurement of mucosal blood volume. In contrast, in cases with thermal or head injury and without acute gastric mucosal lesions, the mucosal blood volume did not decrease significantly as compared with that of the young healthy volunteers and age-matched controls. In conclusion, analysis of mucosal has revealed that ischemia in the gastric mucosa is the main cause of the acute gastric mucosal lesions in patients with thermal or head injury. Further, this study represented noninvasive methodology for the measurement of the gastric mucosal blood volume in patients with gastric diseases.

Adult↗
PubMed1982

Analysis of long-range bullet entrance holes by atomic absorption spectrophotometry and scanning electron microscopy.

Bullet residue and primer particles were analyzed by scanning electron microscopy with energy dispersive analysis (SEM-EDA) and by flame and flameless atomic absorption spectrophotometry (AAS). The residue and particles were on cloth targets around entrance holes produced by bullets fired at distances of 10 to 200 m. Primer particles and their chemical constituents were almost always detected by SEM-EDA around the holes produced by rifles and pistols fired at long ranges, and in many cases the barium and antimony associated with primer particles were detected by flameless AAS. Particles were also detected by SEM-EDA on the rear of bullets fired into and recovered from wooden blocks. Usually a hole caused by a bullet jacketed with gilding metal could be distinguished from one caused by a bullet jacketed with yellow brass alloy. Paint from bullet tips of military tracers was also detected. Analysis of the various residues around entrance holes provides a means for identifying the type of ammunition used.

Barium↗
PubMed1982

Innovations in atomic absorption spectrophotometry with electrothermal atomization for determining lead in foods.

A simple and rapid method is described for the determination of lead in foods. The samples are digested in HNO3, HF, and HClO4 and then the lead is determined by atomic absorption spectrophotometry using an electrothermal atomizer with the L'vov platform. Interferences and ways to improve the precision and accuracy of the analysis were studied. Matrix modification using 1% ammonium phosphate alleviated most interferences encountered. The precision and accuracy of the method was evaluated using NBS SRM 1570 Spinach and SRM 1566 Oyster Tissue. The values obtained are in good agreement with the certified values.

Electrochemistry↗
PubMed1981

Computed tomography and CSF spectrophotometry. Diagnosis and prognosis in 300 patients with cerebrovascular disease.

Computed tomography (CT) has been reported to show normal findings in 13-52% of patients with cerebrovascular diseases. Among factors deciding the diagnostic accuracy are the size and location of the lesion, the time elapsed from onset to examination, the use of contrast enhancement and the type of CT scanner used. To further elucidate these aspects, we designed the present study including 300 consecutive patients, all investigated by CT with a 160 x 160 matrix and cerebrospinal fluid spectrophotometry (CSF-SPE). CT indicated a specific diagnosis in 52.7%. In the majority of the remaining cases, additional subclassification was possible by CSF-SPE, emphasizing the complementary information obtained by combined examinations. CT was also found to be a useful tool for reliable prognostic prediction, irrespective of the initial clinical course.

Adolescent↗
PubMed1980

[Use of solubilization for the preparation of samples for determination of heavy metals in biological materials using atomic absorption spectrophotometry].

Solubilisation was tested for its suitability to prepare organic samples for metal determination. Flameless atomic-absorption spectrophotometry was used as test method. Copper, manganese, zinc, and chromium levels were determined from various organ systems of Wistar rat, in response to "normal" feeding of pelletised standard feed. A comparison between experimentally established concentrations, on the one hand, and literature data, on the other, suggested that solubilisation was applicable with good success to the preparation of samples from which to determine reliable values, in ppm and ppb, of the above elements.

Animal Feed↗
PubMed1980

Electrothermal atomic absorption spectrophotometry of cadmium in semen.

We describe the electrothermal atomic absorption spectrophotometry of cadmium in rabbit semen collected before and after seven days of subcutaneous administration of 0.5 mg of cadmium per kilogram body weight per day. The analytical technique involves combining an aliquot of an acid-digested semen sample with an equal volume of an (NH4)2HOP4 solution (50 g/L), to allow an increase in charring temperature, which results in more nearly complete destruction of matrix. Cadmium values as determined by this method correlated well with those determined by the method of standard additions. The dosing regimen resulted in a statistically significant (p < 0.01) increase in cadmium concentrations in semen (and whole blood) sampled just after the last day of cadmium administration.

Animals↗
PubMed1978

[Analysis of gallstones by infrared spectrophotometry. Advantages and limits of the method (author's transl)].

Numerous clinicians criticise the insufficiency and imprecision, and the incoherency of the analyses of biological calculations by the usual clinical methods and thus frequently avoid prescribing such an examination. The authors propose the application of a physical method, infrared spectrophotometry for the qualitative and semi-quantitative determination of the composition of stones of all origins. They recall the often heterogeneous structure of the stones and emphasise the importance which they attribute of differential analysis by separate zones during careful dissection, the results of which may orient the therapeutic attitude of the clinician. The differentiation of a few crystalline structures and the study of complex mixtures are dealt with in the form of characteristic infrared spectra. The advantages and limits of the method compared with other technics of analysis are discussed.

Bilirubin↗