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PubMed1992

An enzymatic method for measuring serum mannitol and its use in hemodialysis patients.

We evaluated two chemical methods for quantifying mannitol in serum, based on the oxidation of mannitol by periodate, and measurement of the formaldehyde formed with chromotropic acid (colorimetry) or acetylacetone (fluorometry). We found interference in these methods by serum glycerol. Additionally, a high-performance liquid chromatography (HPLC) method was evaluated and found to be specific but impractical for routine use. We therefore, developed an enzymatic fluorometric procedure, based on the oxidation of mannitol by beta-NAD to fructose and NADH, in the presence of the enzyme mannitol dehydrogenase (MD). MD is not commercially available and was partially purified from cultures of Leuconostoc mesenteroides. This new method is specific, sensitive, simple, and accurate and is proposed as the method of choice for measuring mannitol in the serum of patients who received this sugar alcohol during routine hemodialysis treatment.

Chromatography, High Pressure Liquid↗

PubMed1993

Comparison of serum copper determination by colorimetric and atomic absorption spectrometric methods in seven different laboratories. The S.F.B.C. (Société Française de Biologie Clinique) Trace Element Group.

An interlaboratory collaborative trial was conducted on the determination of serum copper using two different methods, based on colorimetry (test combination Copper, Boehringer Mannheim, Mannheim, Germany) and flame atomic absorption spectrometry (FAAS). The general performance of the colorimetric method was below that of FAAS, except for sensitivity and linear range, as assessed by detection limit (0.44 versus 1.32 mumol/L) and upper limit of linearity (150 versus 50 mumol/L). The range of the between-run CVs and the recovery of standard additions were, respectively, 2.3-11.9% and 92-127% for the colorimetric method and 1.1-6.0% and 93-101% for the FAAS method. Interferences were minimal with both methods. The two techniques correlated satisfactorily (the correlation coefficients ranged from 0.945-0.970 among laboratories) but the colorimetric assay exhibited slightly higher results than the FAAS method. Each method was transferable among laboratories.

Analysis of Variance↗

PubMed1995

In vitro quantitative assessment of Echinococcus multilocularis metacestode viability after in vivo and in vitro maintenance.

The aim of this study was to apply the enzymatic MTT (3,5 dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide--formazan colorimetry for quantifying the viability of Echinococcus multilocularis whole cysts, after maintenance in vivo or in vitro. The enzymatic activities of young cysts freshly removed from rodents were linearly correlated with the parasite cyst weight. A comparative evaluation of the MTT assay and the in vitro viability assessments showed that the number of animals used for drug-screening purposes would be reduced by 35.8%. In this way, the use of different parasite samples removed from the same host is required, because of their different ages and their subsequent different abilities to reduce MTT. Cysts removed from mice exhibited higher colorimetric values than those removed from jirds. Thus, small entire cysts obtained from mice were maintained in the CMRL 1066 culture medium. Their enzymatic activities were evaluated at different times. The results indicate that, in such conditions, the optimal period of time for testing the effect of drugs against the metacestodes is limited to the 10 days following their transfer from mouse to culture flasks. The MTT assay encourages further studies to improve the viability of the whole cysts in vitro, using other standardizable culture conditions.

Animals↗

PubMed1985

Which of the commonly used marker enzymes gives the best results in colorimetric and fluorimetric enzyme immunoassays: horseradish peroxidase, alkaline phosphatase or beta-galactosidase?

Comparing the marker enzymes horseradish peroxidase (HRP), alkaline phosphatase (AP) and beta-galactosidase (beta Gal) in IgG-coupled form with respect to their temperature-dependent kinetics over a period of 22 h the temperature of 37 degrees C warrants highest substrate turnover for all enzymes at all reaction times using fluorogens. Also applying chromogens the optimum temperature for beta Gal is 37 degrees C and depends for HRP and AP on the reaction time. The substrate turnover of HRP using ABTS as chromogen is much higher compared to the other enzymes--both related to mol enzyme (molar activity) and to gram enzyme (specific activity). The turnover decreases for all enzymes in different degrees after coupling to IgG. The turnover of fluorogenic substrates is lower for all enzymes than the turnover of chromogenic substrates but due to the more sensitive detection of fluorogenic products the detection limits for all conjugates were lowered too--especially for beta Gal-IgG by a factor of 333 compared to the colorimetric procedure. In a 2-site binding enzyme immunoassay for alpha-1-fetoprotein (AFP) the detection limit for AFP was reduced by a factor of 2 only by the fluorimetry compared to the colorimetry with all 3 marker enzymes. The HRP-IgG conjugates warranted lowest detection limits for AFP (0.5-1 microgram/1), highest analytical sensitivity (slope of standard curves) at shortest periods of substrate reaction compared to the other enzymes.

Alkaline Phosphatase↗

PubMedDate not supplied

Onchocerca gutturosa and O. volvulus: studies on the viability and drug responses of cryopreserved adult worms in vitro.

The viability and drug responses of cryopreserved adult Onchocerca have been examined in vitro. Male worms were cryopreserved in liquid nitrogen (-196 degrees C) using ethanediol as a cryoprotectant in a 2-step incubation procedure. After thawing, 85-90% of O. gutturosa males were normally motile. These motile worms were evaluated for viability using 4 measurements (long-term motility/survival in culture; [U-14C]adenine uptake and leakage; glucose utilization; MTT-formazan colorimetry) and were no different from unfrozen controls. Subsequent experiments demonstrated that the motility responses of cryopreserved worms exposed to the antifilarial drugs ivermectin, CGP 6140 and levamisole were virtually identical to unfrozen controls. Some success was also obtained with this technique in cryopreserving O. volvulus males, with 2 thawed specimens surviving in culture for 93 and 106 d respectively. Following collagenase isolation, female worms were cryopreserved in medium +10% serum without protectant at -79 degrees C. A batch of 8 female O. gutturosa were all motile when thawed 14 d later, with a mean survival time (based on 5 specimens) of 71 d (range 60-90). However, a batch of worms transferred from -79 degrees C to -196 degrees C were badly damaged when thawed. Female O. volvulus were cryopreserved at -79 degrees C in Guatemala and sent by air freight on solid CO2 to the UK. Most specimens were active when thawed. Survival of motile specimens ranged from 7 to 272 d in culture. It is concluded that these techniques are of practical value for the storage and transportation of adult Onchocerca.

Adenine↗

PubMed1978

Hypochromia as a clinical sign of tuberculosis in the tropics.

The skin colour of 106 Nigerian tuberculosis patients was measured by colorimetry; and a relative hypochromia, particularly of the face, was found to be associated with tuberculous infection. The hypochromia reached a significant degree compared to a group of 126 control patients with other medical conditions from whom tuberculosis had been excluded. Successful treatment of the tuberculosis resulted in re-pigmentation. It is suggested that relative hypochromia should be included in the list of non-specific signs which may be looked for when considering tuberculosis in the differential diagnosis of chronic cough, and debilitating disease, in the African. The hypochromia of protein-calorie malnutrition was not included in the study, but its importance in relation to coincident tuberculosis is noted. A simple method of measuring skin colour in the consulting room needs to be developed.

Adolescent↗

PubMed1982

The nature of sialic acids in human lymphocytes.

Analysis of the sialic acids obtained by mild acid hydrolysis of B lymphocytes reveals the presence of N-acetylneuraminic acid and 9-O-acetyl-N-acetylneuraminic acid. For T lymphocytes only N-acetylneuraminic acid has been demonstrated to occur. The applied methods include quantitative colorimetry, thin-layer chromatography and combined gas-liquid chromatography-mass spectrometry.

B-Lymphocytes↗

PubMed1986

Comparative distribution of glycosaminoglycans and proteoglycans in the reproductive tissues of the female fowl.

The objective of this work was to survey and compare the composition of the parts of the reproductive system of the female fowl in glycosaminoglycans and proteoglycans. Those parts analyzed were ovary, infundibulum, magnum, isthmus, shell gland and vagina. Methods of analysis included cellulose acetate electrophoresis, infrared spectroscopy, colorimetry, amino acid determination and scanning electron microscopy. Concentrations of glycosaminoglycans were higher in vagina, ovary, infundibulum and isthmus than in shell gland and magnum. Glycosaminoglycans may be important in those parts of the reproductive tract which contribute membraneous and mucosal material to the descending egg, and where fertilization of the egg occurs.

Amino Acids↗

PubMed1993

Identification of sialic acids on the cell surface of hyphae and yeast forms of the human pathogen Paracoccidioides brasiliensis.

Paracoccidioides brasiliensis, the agent of paracoccidioidomycosis, when grown in a synthetic medium, expresses at the cell surface of both yeast and mycelial forms acidic glycoconjugates containing N-acetylneuraminic acid units. Sialic acids were extracted using mild hydrolytic conditions, and were identified by thin-layer and gas chromatography, standard colorimetry, reaction with periodate-resorcinol and mass spectrometry. Their surface location was inferred from fluorescent-lectin (Limulus polyphemus agglutinin) binding to whole cells abrogated by previous treatment with neuraminidase. Expression of sialic acids on virulent yeast forms of P. brasiliensis (3.7 x 10(6) residues per cell) may inhibit fungal phagocytosis during early infection, when the immunological response is still being built up.

Cell Membrane↗

PubMed1996

Photometric assessment of skin colour and lightness using a tristimulus colorimeter: reliability of inter and intra-investigator observations in healthy adult volunteers.

The ageing of injuries is an important aspect of forensic medicine, and one which can have significant medico-legal consequences. The sequence and timing of color changes associated with the appearance and disappearance of bruises, as well as the factors which govern this process, have long been a source of controversy. Whilst visual assessment currently remains the easiest and most practical method available to date bruises, it appears unlikely that it can be relied upon to provide an accurate and consistent measure of the age of a bruise. In an ongoing pilot study designed to assess the applicability of colorimetry to the dating of bruises, the Dr. Lange MICRO COLOR tristimulus colorimeter will be used to assess how the color and colour density (lightness) of bruises change over time. The results of a preliminary study are presented, in which the variability of skin colour measurements obtained by different investigators was assessed. Measurements were taken of the same area on the volar surface of the forearm of five volunteers, after having them remain with their arm motionless for a predetermined period of time (2, 5, and 10 min). Four sets of measurements were taken by each investigator over a total period of 3 h. No significant statistical difference was found after the resting time interval of 5 min between the values obtained by the two investigators (P > 0.05). While studies on a much larger population remain to be completed, our initial findings would seem to suggest that the colorimeter is able to provide an objective, quantitative, and relatively consistent measure of skin colour when used by different individuals.

Adult↗

PubMed1995

Parathyroid hormone-related protein and calcium concentrations in milk and blood of ewes.

Parathyroid hormone-related protein (PTHrP) and calcium (Ca) concentrations were measured 2 to 3 months postpartum in milk and plasma or serum of 22 ewes by the use of commercial radioimmunoassay kits for PTHrP concentration, colorimetry for serum total Ca concentration (Catot), and atomic absorption spectrophotometry for milk total Ca concentration. Scatter plots did not reveal dependency between milk Ca and Catot, Catot and plasma PTHrP, milk Ca and milk PTHrP, and milk PTHrP and plasma PTHrP. Thus, the systemic and mammary effects of PTHrP are not major determinants of the endocrine, paracrine, and autocrine regulation of Ca homeostasis during lactation in ewes.

Animals↗

PubMed1996

Calcitonin mRNA expression and plasma calciotropic hormones in fetal lambs.

The object of this study was to measure basal levels of calciotropic hormones during gestation in the ovine fetus. Thyroid glands and plasma samples were collected from 49 Ile de France x (Limousine x Romanov) fetuses (range, 80 to 145 d). Total thyroidal RNA was extracted for calcitonin (CT) mRNA analysis. Plasma immunoreactive concentrations of CT, parathyroid hormone (PTH), parathyroid hormone-related peptide (PTHrP), and 1,25-dihydroxy-vitamin D [1,25-(OH)2D] were assayed. Plasma Ca and P concentrations were measured by atomic absorption spectrophotometry and colorimetry, respectively. The ratio of thyroidal weight/body weight decreased twice between Days 80 and 145 of gestation. Simultaneously, the CT mRNA rate increased but did not significantly vary after 89 d of gestation. Plasma CT concentration increased between 80 and 89 d and then did not significantly vary until Day 145. We could not detect PTH in ovine fetuses plasma; PTHrP concentration did not vary significantly between Days 80 and 145. The concentration of 1,25-(OH)2D decreased in plasma essentially between Days 110 and 145. In conclusion, between Days 80 and 145 of gestation, CT, PTHrP, and 1,25-(OH)2D concentrations can be easily measured in plasma from ovine fetuses, but plasma PTH was undetectable. In basal conditions, no relationship could be demonstrated between any hormonal concentrations in the fetal plasma and that of Ca or P.

Animals↗

PubMed2006

Serum free Fatty acids and glucose metabolism, insulin resistance in schizophrenia with chronic antipsychotics.

BACKGROUND: Weight gain and type 2 diabetes mellitus (DM) are often linked to antipsychotics treatment. The aim of the study is to investigate serum free fatty acids (FFA) levels in schizophrenic patients who received long-term antipsychotics treatment, and to explore the associations between serum FFA and fasting blood glucose, and insulin resistance. METHODS: 308 inpatients with schizophrenia who met with the criteria of DSM-IV were recruited into this study, and were divided into four groups: control subjects, single obesity, impaired glucose tolerance (IGT) and type 2 DM according to different body mass index, fasting blood glucose level and 2-hour postprandial blood glucose. Serum FFA was measured with colorimetry. Serum insulin and leptin were measured with radioimmunoassay respectively. RESULTS: There was a significant elevation in serum FFA levels in schizophrenic patients who received long-term antipsychotics treatment, especially in single obesity, IGT, and DM groups. The elevated serum FFA was remarkably positive correlated with fasting blood glucose and insulin resistance. CONCLUSIONS: The study suggested the elevated serum FFA in schizophrenic patients with long-term antipsychotics treatment affected the blood glucose metabolism, may have played an important role in insulin resistance and type 2 DM, and was also an important trait of metabolic syndromes.

Adult↗

PubMed2004

Evidences for the formation of bisbenzamidine-heme complexes in cell-free systems.

Infrared and colorimetry data suggest that bisbenzamidines connected by various rigid or flexible linkers are able to interact with heme in cell-free systems. At pH 5.0 the inhibition of formation of beta-hematin could be ascertained by infrared spectroscopy whereas at pH 7.0 the interaction yielded insoluble complexes for which a sandwich-type structure of stoichiometry 2:1, heme-drug, is tentatively proposed.

Animals↗

PubMed2004

Overestimation of rifampicin during colorimetric analysis of anti-tuberculosis products containing isoniazid due to formation of isonicotinyl hydrazone.

When present together in fixed-dose combinations (FDC) of anti-tuberculosis drugs, rifampicin (R) and isoniazid (H) interact with each other to form isonicotinyl hydrazone (HYD). In a preliminary study, this product was found to possess similar colorimetric spectrum to that of rifampicin. Therefore, an investigation was undertaken to determine interference of HYD during analysis of rifampicin in FDC products by colorimetry. For the purpose, standard plots were constructed for rifampicin and HYD at 475 nm, the wavelength maximum for both the compounds. The plots were linear in the range of 10-100 microg/ml. Molar absorptivity values for rifampicin and HYD were 15279 and 5034, respectively. It indicated that HYD possessed one-third absorptivity to that of rifampicin. The analysis of combinations of rifampicin and HYD revealed that rifampicin could be overestimated to a maximum extent of 33%, while interference varied at other relative ratios of the two compounds. This was also confirmed by colorimetric and HPLC analysis of a degraded marketed product and samples from a dissolution study. Thus this investigation suggests that any method devoid of interference of HYD should be preferred for analysis of rifampicin, whenever it is present along with isoniazid.

Antitubercular Agents↗

PubMed2004

Enhancement of bone formation in rat calvarial bone defects using low-level laser therapy.

OBJECTIVE: To evaluate the effect of low-level laser therapy (LLLT), using a GaAlAs diode laser device, on bone healing and growth in rat calvarial bone defects. STUDY DESIGN: An animal trial of 4 weeks' duration was conducted using a randomized blind, placebo-controlled design. Standardized round osseous defects of 2.7 mm diameter were made in each parietal bone of 20 rats (n=40 defects). The animals were randomly divided into an experimental and a control group of 10 animals each. In the experimental group, a GaAlAs diode laser was applied immediately after surgery and then daily for 6 consecutive days. The control group received the same handling and treatment, but with the laser turned off. Five rats from each group were killed on day 14 and the remainder on day 28 postoperatively. From each animal, tissue samples from one defect were prepared for histochemistry and samples from the contralateral defect for histology. Levels of calcium, phosphorus, and protein were determined by using atomic absorption spectrometry, colorimetry, and photometry, respectively. Student t-test and Mann-Whitney were used for statistical analyses. RESULTS: At both time points the tissue samples from the experimental animals contained significantly more calcium, phosphorus, and protein than the controls. Similarly, histological analyses disclosed more pronounced angiogenesis and connective tissue formation, and more advanced bone formation in the experimental group than in the controls. CONCLUSION: LLLT may enhance bone formation in rat calvarial bone defects.

Aluminum↗

PubMed1997

Measurement of glutamine synthetase activity in rat muscle by a colorimetric assay.

Glutamine synthetase catalyses the formation of L-Gln from L-Glu and NH4+. This enzyme also exerts a glutamyl-transferase activity that produces gamma-glutamyl-hydroxamate from Gln and hydroxylamine. This gamma-glutamyl-transfer reaction can be used to determine glutamine synthetase activity by colorimetric assay. This method has never been applied to rat muscle. The aim of this work was to study and optimize the glutamine synthetase assay conditions in rat muscle. Enzyme activity was linear with time of incubation (30 min at 37 degrees C) and linear with enzyme concentration in the incubation medium. The method was specific. In addition, this assay correlated well with a radiometric assay (y = 0.76x + 340, where x and y are the glutamine synthetase activities measured by radiometry and colorimetry respectively; r = 0.94; P = 0.05). Finally, no glutamine synthetase activity was found in muscles of rats treated with methionine sulfoximine, an inhibitor of glutamine synthetase, and activity dramatically rose in muscles from rats treated with dexamethasone, an activator of glutamine synthetase (in extensor digitorum longus: 2717 +/- 54 nmol/min/g protein in dexamethasone-treated rats versus 1228 +/- 114 nmol/min/g protein in control rats, P < 0.0001). In conclusion, the method presented here is accurate and reliable for measurement of glutamine synthetase activity in muscles.

Animals↗

PubMed2003

Variability of porcelain color reproduction by commercial laboratories.

STATEMENT OF PROBLEM: Many investigations in the field of metal ceramics have examined materials, manipulative variables, and the relationship of these factors to a restoration's color. However, the effect of the artistic component of restoration fabrication is not known. PURPOSE: The purpose of this study was to determine through instrumental colorimetry the variability in color reproduction for metal ceramic crowns fabricated by commercial dental laboratory technicians. MATERIALS AND METHODS: Fifty metal ceramic crowns were fabricated on standardized metal frameworks to the same shade specifications by 5 commercial dental laboratories (n=10). Laboratory prescriptions requested that the technician match the shade and translucency of a provided Vita Lumin A3.5 shade tab. Technicians used the porcelain and technique of their own selection to match the tab. Color differences were determined by use of a colorimeter between crowns and the prescribed shade tab at middle and incisal sites. Analysis of variance was used to determine whether differences in color reproduction existed among laboratories. Where statistically significant interactions existed, the Tukey honestly significant difference test was used to determine significant differences between laboratories according to sites (alpha=.05). RESULTS: Color reproduction was significantly different (P <.0001) among laboratories for both sites. Mean color difference from shade tabs ranged from 3.5 to 11.1 DeltaE units. All laboratories were better at matching shades in the incisal third of the crown. CONCLUSION: Within the limitations of this study, the ability to reproduce the color of the target shade tab differed among laboratories. Most crowns fabricated by the laboratories in this study, when compared to the prescribed shade tab, were above the clinical threshold for an acceptable shade match under intraoral conditions (DeltaE 3.7).

Analysis of Variance↗