New rapid kit for determining calcium in serum and urine evaluated. (17/21)

We describe the performance of a colorimetric reagent kit (Diagnostic Systems Laboratories, Inc., Webster, TX 77598) for measuring calcium directly in urine, serum, and ultrafiltered serum, and compare the results with those obtained with atomic absorption spectrophotometry. The CV for within-run precision was 2.8 and 2.1% for urine and whole serum, respectively (n = 10 each). Between-run precision for urine, whole serum, and ultrafiltered serum was 1.9, 1.6, and 2.2%, respectively (n = 8 to 10). Analytical recovery of added calcium from three different urine and serum specimens, to which three different concentrations of calcium had been added, was 101.9 (SD 0.3%) for urine and 100.9 (SD 0.2%) for serum. Assay of 30 urine specimens, 15 ultrafiltered serums, and 20 whole serums by both the kit and atomic absorption spectrophotometry demonstrated correlation coefficients of 0.993, 0.828, and 0.751, respectively. Mg2+, hemolysis, or lipemia does not interfere. Compared with atomic absorption spectrophotometry, the calcium kit procedure is rapid and simple.  (+info)

Dye-containing buffered charcoal-yeast extract medium for differentiation of members of the family Legionellaceae. (18/21)

The addition of 0.001% bromocresol purple and 0.001% bromothymol blue to buffered charcoal-yeast extract agar allowed differentiation between members of the family Legionellaceae. On this medium, Legionella pneumophila grew as relatively flat, pale green colonies, whereas Tatlockia micdadei (gen. nov., comb. nov., Pittsburgh pneumonia agent) produced blue-gray colonies. Fluoribacter spp. (gen. nov., atypical Legionella-like organisms) developed glistening colonies which were brighter green than those of L. pneumophila.  (+info)

Renal handling of phenol red. II. The mechanism of substituted phenolsulphophthalein (PSP) dye transport in rabbit kidney tubules in vitro. (19/21)

1. The uptake of various substituted phenolsulphophthalein dyes by cortical slices of rabbit kidney has been studied in detail in order to obtain more information on the secretory system for organic anions. 2. The rate of initial uptake of dyes and the accumulation after incubation for 2 hr under aerobic conditions increased in the order: phenol red (PR) greater than bromophenol blue (BPB) greater than bromocresol green (BCG) greater than bromothymol blue (BTB), while the reverse order of uptake was observed under anaerobic conditions. There was no difference between the uptake of BTB under aerobic and anaerobic conditions. 3. The accumulation of dyes under anaerobic conditions could be accounted for by binding to tissue constituents. In comparison with PR (Sheikh, 1972), the substituted dyes were found to interact extensively with the 700 G (cell membranes) and cytosol fractions of renal homogenates. 4. Low concentrations of the substituted dyes efficiently inhibited the accumulation of rho-aminohippurate (PAH). The concentration of dye resulting in 50% inhibition of PAH accumulation (KI) agreed well with concentrations estimated to sustain 50% of maximal dye transport (KM). On this basis the affinity of the dyes for the transport system increases in the order: PR less than BPB less than BCG less than BTB. 5. Probenecid, 2,4-dinitrophenol, PAH, octanoate and succinate affected to a smaller extent the uptake and binding of BPB and BCG by renal tissue than that previously shown for PR (Sheikh, 1972). No inhibitory effect of these substances on the accumulation of BTB by kidney tissue was observed. 6. The binding of PSP dyes by phospholipid vesicles (liposomes) and a representative binding protein, human serum albumin, exhibited close similarity to that of binding by renal tissue. Partition experiments involving octanol-water phases indicated that the hydrophobicity of the dyes increased in the order: PR less than BPB less than BCG less than BTB. 7. The results indicate that BTB, despite its inhibitory potency, is not transported by the organic anion system. BPB and BCG are transported to a lesser extent, and interact more strongly with the transport system than does PR. It is suggested that the substituted dyes by virtue of hydrophobic interaction with the transport system reduce the movement of the mobile part of the transport system.  (+info)

Bromothymol blue as a probe for structural changes of model membranes induced by hemoglobin. (20/21)

The effect of methemoglobin on the structure of model membranes composed of phosphatidylcholine and diphosphatidylglycerol (18 : 1, mol : mol) was studied with the help of pH-indicator dye bromothymol blue. The partition coefficients characterizing the dye binding to methemoglobin or model membranes were derived from the pKaalpha dependences on the protein or phospholipid concentration. The observed character of the dye partitioning in the lipid or lipid-protein systems is interpreted in terms of the traditional electrostatic approach and some modern theories of membrane electrostatics. It is assumed that methemoglobin affects the structural and physicochemical parameters of lipid-water interface.  (+info)

Stabilization of bromthymol blue colour in lecithin-sphingomyelin ratio determinations in amniotic fluid. (21/21)

Amniotic fluid lecithin and sphingomyelin areas after extraction and chromatography are rendered permanently visible by the use of bromthymol blue dye buffered to a pH of 11-3.  (+info)