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PubMed1993

Precipitant stressors in adolescent suicide.

OBJECTIVE: Precipitant stressors in adolescent (aged 13 to 19 years) suicides (N = 53) were investigated in a nationwide psychological autopsy study in Finland. METHOD: Data were collected through interviews with the victims' parents and health care personnel, and from official records. RESULTS: Precipitants during the month preceding suicide were found in 70% of the cases. Almost half the precipitants occurred during the last 24 hours. Interpersonal separations and conflicts were the most common precipitants. Compared with other suicide victims, those with weakened parental support more often had interpersonal separation as a precipitant, a higher number of stressors during the final month, and had more often experienced major stress during the year before suicide. CONCLUSION: The findings highlight the importance of stress (acute, chronic, or both) in adolescent suicide. Interpersonal problems were common precipitants in adolescent suicide. Among adolescents with weakened parental support, interpersonal separations were especially common precipitants. Additional research on precipitants in adolescent suicide is needed with proper control subjects.

Adolescent↗

PubMedDate not supplied

Use of NADP archive samples to determine the isotope composition of precipitation: characterizing the meteoric input function for use in ground water studies.

Stable oxygen and hydrogen isotopes have been used in ground water studies to investigate recharge, mixing, ground water/surface water interaction, advective-diffusive transport, paleohydrogeologic interactions and to estimate ground water ages. Such studies require that the isotopic composition of precipitation be known, as precipitation is a major input to ground water and surface water systems. As oxygen-18 and deuterium data for precipitation are lacking across much of the United States, there is need to establish additional local meteoric water lines as isotope input functions across the region, as well as to develop better understanding of the isotopic climate linkages that control oxygen and hydrogen isotope ratios in precipitation. In the absence of long-term monitoring stations, one possible solution to this problem is to determine the delta 18O and delta 2H values of precipitation using archive samples collected at monitoring stations managed by the National Atmospheric Deposition Program (NADP). This study describes and interprets the seasonal delta 18O and delta 2H composition of archived precipitation samples collected in eastern Nebraska near the town of Mead during the years 1992-1994. Values for delta 18O range from -23.6 to -0.7@1000. Values for delta 2H range from -172 to 0@1000. Yearly arithmetic mean delta 18O and delta 2H values for the Mead station are -8.1@1000 and -53@1000, respectively. Weighted yearly means for delta 18O and delta 2H were -7.4@1000 and -48@1000, respectively. Mead values show a strong isotopic enrichment between winter and summer precipitation, and a strong delta 18O-T correlation (r2 = 0.91) for mean monthly values of about 0.5@1000 per degree Celsius. The local meteoric water line for the Mead site is delta 2H = 7.40 delta 18O + 7.32. Deuterium excess values suggest that most of the moisture across the region is derived primarily from a Gulf of Mexico source. The results of this study demonstrate that in the absence of long-term monitoring stations such as those operated globally by the International Atomic Energy Association, NADP archive samples can be used to determine the isotopic composition of precipitation, to characterize the local meteoric water line and establish the various climatic relationships, and define the meteoric input function for use in ground water studies.

Deuterium↗

PubMed1984

Precipitation of the thyrotropin receptor and identification of thyroid autoantigens using Graves' disease immunoglobulins.

The thyrotropin (TSH) receptor is a putative target for autoantibodies in Graves' hyperthyroidism and therefore, should be capable of being identified, isolated, and structurally characterized by immunological means. To this end, four sera from patients with hyperthyroidism, three of which inhibited the binding of 125I-TSH to Triton-solubilized human thyroid membranes, were used to isolate TSH receptors by immunoprecipitation. To account for an effect of TSH binding or receptor occupancy on the ability of Graves' immunoglobulins to precipitate TSH receptors, two approaches were taken: (a) specific 125I-TSH binding activity was measured after solubilized thyroid membranes had been incubated with Graves' sera followed by precipitation with Staphylococcus protein A ("receptor depletion"); (b) TSH binding sites were labeled with 125I-TSH and the complexes were precipitated using Graves' sera and Staphylococcus protein A ("receptor precipitation"). The three sera which inhibited 125I-TSH binding depleted 125I-TSH binding activity between 30-80%. Preformed complexes between Staphylococcus protein A and immunoglobulins in these sera were also able to deplete 125I-TSH binding activity. However, after receptor depletion, the one serum that did not inhibit 125I-TSH binding was associated with a significant increase in 125I-TSH binding. All four sera specifically precipitated 80-100% of receptors identified by prelabeling with 125I-TSH. The dilutions of sera that precipitated 50% of 125I-TSH-receptor complexes ranged from 1:150-1:20. Complexes were partially precipitated by high concentrations of control sera (1:20), but the relative potency of control sera was at least fourfold less than Graves' sera. Immunoprecipitates of 125I-labeled thyroid membranes were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography to reveal Graves'-specific bands of reduced molecular weights of 100-110,000, 80-90,000, and 70-75,000. These bands were similar to those obtained from 125I-labeled thyroid membranes purified by TSH affinity chromatography. Thus, Graves' immunoglobulins: (a) precipitate unoccupied and occupied TSH receptors, (b) in one case, neither inhibit binding nor immunodeplete the unoccupied receptor but immunoprecipitate 125I-TSH-receptor complexes, suggesting that binding of TSH may initiate an interaction between the binding site and a separate immunoreactive molecule, and (c) identify the molecular structure of Graves' autoantigens, putatively, the TSH receptor.

Animals↗

PubMed1988

Precipitated bone phosphate in broiler chick diets.

Day-old Cobb x Cobb broiler chicks were housed in battery brooders for 21-day feeding periods during two experiments. Dietary treatments consisted of a corn-soybean starter feed (.37% total; .14% nonphytin phosphorus) supplemented with 0, .05, .10, .15, or .28% phosphorus in the form of dicalcium phosphate, precipitated bone phosphate, or a mixture of soft and precipitated phosphates (each providing 50% of the phosphorus addition). Total dietary calcium was held constant at .90%. Comparable dietary phosphorus from precipitated bone and the soft-precipitated mixture supported body weights statistically equivalent to those of dicalcium phosphate treatments. Tibia ash results at suboptimal phosphorus levels, with one exception, indicated statistically equal utilization from the soft-precipitated combination. Slope-ratio techniques using tibia ash and total nonphytin phosphorus intake established the bioavailability of phosphorus from precipitated bone was 120% when dicalcium phosphate was the standard. The data indicate that precipitated bone phosphate for broilers was fully equivalent in performance to dicalcium phosphate. Providing one-half the supplemental phosphorus from both soft phosphate and precipitated bone seemed to be an acceptable method of meeting practical phosphorus requirements.

Animal Nutritional Physiological Phenomena↗

PubMed2002

The effect of topography, season and weather situation on daily precipitation gradients in 60 Swiss valleys.

Daily precipitation in the Swiss valleys decreases frequently with altitude, particularly in southern Switzerland. Only one-third of precipitation days show positive precipitation gradients with a fairly strong correlation of precipitation with altitude (R2 > or = 0.5). Generally, precipitation gradients are larger in the north than in the south but there are large differences among valleys situated near to each other. The effects of precipitation amount, weather situation, region and season, wind speed and topography were not very significant at all. It seems that the positioning of the upper and lower precipitation gauges under specific topographic and climate conditions can affect the precipitation gradients in a particular valley.

Altitude↗

PubMed1986

[Decreased effectiveness of cold-induced heparin precipitation of plasma fibronectin in infection].

Plasma fibronectin (FN) is one of the major blood opsonins. The content of the glycoprotein reduces in sepsis which in turn may aggravate the course of the infection. FN is detectable in the content of cryoglobulins and cryofibrinogen. The formation of the heparin precipitate following plasma incubation in the cold in the presence of heparin is determined by FN involvement. Fibrinogen (FG) is another main component of the heparin precipitate. To determine the functional activity of plasma FN in sepsis and other pathological conditions, a study was made of the ability of FN and FG to go into the precipitate formed in blood plasma in the cold after its incubation with heparin. Unlike normal subjects in whom over 80% of FN on the average and about 20% of FG went into the heparin precipitate, in patients with hemoblastoses and aplastic anemia complicated by sepsis, less than 40% of FN on the average and about 7% of FG went into the precipitate. In some patients with sepsis, the heparin precipitate did not form. The reduction of FN ability to go into the heparin precipitate correlated with the gravity of the patients' condition. In uncomplicated hemoblastoses, cryoglobulinemia and cryofibrinogenemia and in immunocomplex pathology, the consumption of FN and FG during heparin precipitate formation did not significantly differ from the control. The data indicate that sepsis patients with blood system pathology may develop not only quantitative FN deficiency in the blood but also disorder of the functional activity of the opsonin.

Adolescent↗

PubMed2000

Effect of zinc binding and precipitation on structures of recombinant human growth hormone and nerve growth factor.

Metal-induced precipitation of protein therapeutics is being used and further developed as a processing step in protein formulation and may have utility in protein purification and bulk storage. In such processes, it is imperative that native protein structure is maintained and the metal complexation is reversible. In the current study, we investigated the effects of zinc-induced precipitation on recombinant human growth hormone (rhGH) and recombinant human nerve growth factor (rhNGF). On the addition of ethylenediaminetetraacetic acid (EDTA), the precipitates were dissolved, yielding complete recovery of native protein in both cases. Both proteins have specific metal binding sites and require specific molar ratios of zinc to protein to initiate precipitation (zinc:rhGH > 2:1; zinc:rhNGF > 18:1). Furthermore, the secondary structures of both proteins were unperturbed in soluble zinc complexes and zinc-induced precipitates, as measured by infrared and circular dichroism spectroscopies. The soluble zinc complex of rhGH had minor tertiary structural alterations, whereas zinc binding did not alter the tertiary structure of rhNGF. These studies indicated that metal-induced precipitation provides a method to maintain proteins in their native state in precipitates, which may be useful for purification, storage, and formulation.

Binding Sites↗

PubMed1994

Calcium phosphate precipitation on the surface of HA-G-Ti composite under physiologic conditions.

Hydroxyapatite-glass-titanium (HA-G-Ti) functionally gradient composite plates bound face-to-face by nylon wire were soaked in a simulated body fluid. The gap between the plates was filled with the precipitates after soaking for 6 months, and a tight chemical bond was formed between them. Field emission-type (FE) scanning electron microscopy (SEM) and transmission electron microscopy observations revealed that the growth rate and morphology of the precipitates differed widely from the outside portion to the inside one on the surface region of the composite plates. In the portion relatively near the outside, the mutually bonded portion, needle-like precipitates with preferred orientation to the c-axis were markedly observed. From the results of Fourier transform infrared spectroscopy and energy dispersive x-ray microanalysis, it was found that the precipitates were Ca-deficient carbonate apatite with low crystallinity. On the other hand, HA-G-Ti composite rods were implanted in the femur of beagle dogs for 3 months. FE-SEM observations demonstrated that needle-like precipitates were deposited on both the surfaces of the composite and bone at the portion having a narrow gap, about 0.1-0.2 mm between them prepared deliberately before implantation. It was found that both the morphologies and the composition of the precipitates in vivo were similar to those in vitro. It is concluded that the HA particles on the surface of the composite act as nucleation sites for precipitation in physiologic environments, whereas the glass matrix is independent to it.

Animals↗

PubMed1994

A selective precipitation purification procedure for multiple phosphoseryl-containing peptides and methods for their identification.

Multiple phosphoseryl-containing sequences of proteins stabilize amorphous calcium phosphate and have been implicated in the regulation of biomineralization, protein structure, and enzyme activity. To facilitate studies on the identification and characterization of multiple phosphoseryl-containing sequences of proteins we have developed a simple and efficient purification procedure involving precipitation of Ca2+/ethanol-induced aggregates of the multiple phosphoseryl-containing peptides from enzymic digests. The multiple phosphoseryl-containing peptides of a tryptic digest of casein were selectively precipitated using Ca2+ (20 mol/mol protein) and 50% (v/v) ethanol at pH 3.5, 4.6, and 8.0. The individual peptides of the precipitates were purified using anion-exchange fast-performance liquid chromatography and reversed-phase HPLC and then identified by solid-phase sequence analysis and amino acid composition analysis after vapor-phase hydrolysis. Prior to sequence analysis the phosphopeptides were covalently coupled to arylamine membranes and the phosphoseryl residues converted to S-ethylcysteinyl residues by calcium-ion-catalyzed beta-elimination in the presence of ethanethiol. The modified peptides were sequenced using an Applied Biosystems Inc. automated protein sequencer fitted with a membrane cartridge. Only peptides containing the cluster sequence -Ser(P)-Ser(P)-Ser(P)- were precipitated by Ca2+/ethanol at pH 3.5. The pH 4.6 precipitate contained all the cluster peptides plus two diphosphorylated peptides containing -Ser(P)-Glu-Ser(P)- and -Ser(P)-Thr-Ser(P)-. At pH 8.0, a monophosphorylated peptide containing -Ser(P)-Glu-Glu- was also present in the precipitate with the diphosphorylated and cluster peptides. The recoveries of the peptides in the pH 8.0 selective precipitate ranged from 83 to 95% of that present in the hydrolysate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1994

Fractionation of heparin, dermatan sulfate, and chondroitin sulfate by sequential precipitation: a method to purify a single glycosaminoglycan species from a mixture.

Purified heparin, dermatan sulfate, and chondroitin sulfate in mixtures were fractionated by sequential precipitation with increasing volumes of acetone and analyzed by agarose-gel electrophoresis and for M(r), charge density, constituent disaccharides, and anticoagulant activity (for heparin). Purified glycosaminoglycans are generally utilized for pharmaceutical purposes and show physicochemical properties of glycosaminoglycans used as drugs. Heparin is the first glycosaminoglycan to precipitate at low percentages of acetone. The relative amount of slow moving and fast moving components, the M(r) and charge density, and the disaccharide pattern of fractionated heparin depend on the percentage of solvent. The activated partial thromboplastin time activity of fractions composed of heparin decreases with the charge density and M(r). Dermatan sulfate is precipitated by acetone over a narrow range (0.6-0.7 vol, 37-41%), and one of these fractions is constituted by 100% of this polysaccharide. These species of dermatan sulfate have different percentages of constituent disaccharides compared to the native polysaccharide. Nonsulfated disaccharide and disaccharide-6-sulfate are enriched. The dermatan sulfate species precipitated by acetone are also enriched in disaccharide-4,6-disulfated. Chondroitin sulfate is the most soluble glycosaminoglycan in mixed acetone/water solvent. It begins to precipitate at 0.8 vol (44%) of acetone. Different species of chondroitin sulfate can be recovered by precipitation at different percentages of solvent, and they show a decrease in M(r) and charge density depending on the percentage of acetone. The chondroitin sulfate species fractionated are also enriched in disulfated disaccharides compared to native polysaccharide. A different distribution of the three disulfated disaccharides can be pointed out in the fractionated chondroitin sulfate. Sequential precipitation performed by carefully increasing acetone percentages can help obtain purified species of glycosaminoglycan with desired properties from a mixture and tissue extracts, and achieve savings in time.

Animals↗

PubMed1996

N,N'-bis[3,3'-(dimethylamino)propylamine]-3,4,9, 10-perylenetetracarboxylic diimide, a dicationic perylene dye for rapid precipitation and quantitation of trace amounts of DNA.

A novel dicationic dye with a polycyclic aromatic perylene core and flexible cationic side chains- N,N'-bis[3, 3'-(dimethylamino)propylamine]-3,4,9,10-perylenetetracarboxylic diimide-termed "DAPER," was synthesized and characterized. The dye appears to exist in a highly stacked form in aqueous solution. DAPER precipitates extremely low concentrations of DNA very rapidly, efficiently, and with a stoichiometry of one tightly bound dye per DNA base pair, corresponding to a neutral complex. Precipitation may occur due to side-by-side association between the polyanionic DNA helix and polycationic dye stacks. DNA precipitation by DAPER is less sensitive to DNA concentration and length, and prevailing salt concentrations, than precipitation with ethanol or propanol. DAPER can be quantitatively extracted from DNA into a standard phenol:chloroform mixture under slightly alkaline conditions. The recovered DNA is suitable for treatment with enzymes typically used in DNA sequencing procedures. The amount of DNA precipitated is accurately determined by visible absorption or fluorescence spectroscopic analyses of the phenol:chloroform extracts. Several samples of DNA can be precipitated, recovered, and quantitated in about 1 h using standard microscale procedures and equipment. The unique qualities of DAPER provide the basis for a very sensitive, rapid, and versatile method for simultaneous precipitation and quantitation of microgram and submicrogram amounts of DNA.

1-Propanol↗

PubMed1986

Fibronectin in polyethylene glycol precipitates: evidence for a role in immune complexes.

Fibronectin is involved in the opsonic clearance of particulate material. It is present in plasma and synovial fluid and thus might be expected to have a role in the clearance of immune complexes. We have investigated this in a study of polyethylene glycol (PEG) precipitable material from the serum of patients with rheumatoid arthritis, systemic lupus erythematosus, and other connective tissue disorders. Fibronectin is a significant component of PEG precipitates but the amount present is influenced by the method of preparation: more precipitates at 4 degrees C than at 20 degrees C. Fibronectin precipitation by PEG was considered to be related to immune complexes because: there was no direct relationship between serum fibronectin levels and the amount present in PEG precipitates; radiolabelled purified isolated fibronectin did not precipitate in 4% PEG; there was a direct relationship between the amount of fibronectin in PEG precipitates and the amounts of immunoglobulin G, A, and M. These results indicate that fibronectin is involved in immune complexes in rheumatic diseases, though they do not show it has an important biological role in these circumstances.

Antigen-Antibody Complex↗

PubMed1989

Separation of bone matrix proteins by calcium-induced precipitation.

It was found that significant precipitation occurred immediately after calcium, at a concentration as low as 2 mM, was added to a desalted solution of EDTA extract of adult bovine femur. The maximal yield of the precipitates was observed at a calcium concentration of 30 mM. These precipitates were dissolved in 0.5 M EDTA, desalted, and characterized by Sepharose CL-6B gel filtration chromatography and high performance gel-exclusion chromatography. Results revealed that the precipitates were enriched in a 40 K protein and a higher molecular weight fraction as compared with the original extract of bone proteins. The 40 K fraction was isolated and identified as osteonectin, as judged from amino acid analysis, electrophoresis, and immunodetection. The supernatant after calcium-induced precipitation predominantly contained osteocalcin and a 50 K protein that was tentatively identified as alpha 2HS protein. Osteonectin was purified from the calcium-induced precipitates from the EDTA extract of bovine bone. By calcium titration using fluorescence spectrometry, the isolated osteonectin showed high affinity to calcium ions with an apparent dissociation constant (K0.5) of 8 x 10(-7) M. Thus, the use of calcium to separate bone proteins, especially osteonectin, was proved to be a useful technique. In addition, calcium-induced precipitation of osteonectin suggested a possible in vivo mechanism via which osteonectin might interact with calcium ions and participate in the initial immobilization of calcium to induce the nucleation of calcification in bone tissue.

Animals↗

PubMed2006

Precipitation of minerals by 22 species of moderately halophilic bacteria in artificial marine salts media: influence of salt concentration.

Precipitation of minerals was shown by 22 species of moderately halophilic bacteria in both solid and liquid artificial marine salts media at different concentration and different Mg2+-to-Ca2+ ratio. Precipitation of minerals was observed for all the bacteria used. When salt concentration increased, the quantity and the size of bioliths decreased, the time required for precipitation being increased. The precipitated minerals were calcite, magnesian calcite, aragonite, dolomite, monohydrocalcite, hydromagnesite and struvite in variable proportions, depending on the bacterial species, the salinity and the physical state of the medium; the Mg content of the magnesian calcite also varied according to the same parameters. The precipitated minerals do not correspond exactly to those which could be precipitated inorganically according to the saturation indices. Scanning electron microscopy showed that the formation of the bioliths is initiated by grouping of calcified cells and that the dominant final morphologies were spherulitic with fibrous radiated interiors. It was demonstrated that moderately halophilic bacteria play an active role in the precipitation of carbonates and we hypothesize about this process of biomineralization.

Bacillaceae↗

PubMed1998

Precipitate formed by thiopentone and vecuronium causes pulmonary embolism.

PURPOSE: To examine the effects of a bolus injection of the precipitate formed by thiopentone and vecuronium on the pharmacokinetic behaviour of thiopentone, cardiopulmonary physiology, and lung histology. METHODS: Of 16 female rabbits (2.9 to 3.1 kg), eight were injected with a precipitate formed by a mixture of 5 mg.kg-1 thiopentone and 0.67 mg.kg-1 vecuronium via the external jugular vein. Eight control rabbits were injected with 5 mg.kg-1 thiopentone alone. Plasma thiopentone concentration, systolic arterial pressure and PaO2 were measured for 60 min after injection. Histological changes in the lungs were evaluated at one and 60 min. RESULTS: Maximum blood thiopentone concentration in the precipitate group was lower than in the control group (12.9 +/- 4.5 vs 17.0 +/- 1.6 micrograms.ml, P < 0.05), although the half-life of thiopentone in the precipitate group was longer (32.3 +/- 8.5 vs 21.7 +/- 8.2 min, P < 0.05) and the area under the time concentration curve was similar between the two groups. However, the mean residence time was 28% longer in the precipitate group than in controls (P < 0.05). The PaO2 was lower in the precipitate group than in controls one minute after injection (431 +/- 27 vs 464 +/- 18 mmHg, P < 0.05) but not subsequently. Histologically, crystals (30-150 microns in diameter) obstructed small arteries in the lungs at one minute but not at 60 min after injection. CONCLUSION: Intravenous injection of precipitate causes pulmonary microembolism, with a small transient decrease in PaO2.

Anesthetics, Intravenous↗

PubMed1996

The precipitate formed by thiopentone and vecuronium.

PURPOSE: To determine the composition and solubility of the precipitate formed by thiopentone and vecuronium in vitro. METHODS: The precipitate formed by mixing thiopentone 2.5% and vecuronium 0.1% at room temperature was analyzed by ultraviolet spectrophotometry and high performance liquid chromatography (HPLC). The solubility of the precipitate in human plasma was measured by HPLC. RESULTS: The UV absorption spectrum of the precipitate resembled that of thiopentone. HPLC analysis produced a single peak with the same retention time as thiopentone (4.6 min). In human plasma the solubility of the precipitate was not different from that of thiopentone acid. The solubility of thiopentone was greater than that of the precipitate. CONCLUSION: The precipitate formed by thiopentone and vecuronium in vitro consisted of thiopentone acid, which was insoluble in human plasma.

Chemical Precipitation↗

PubMed2007

Stochastic simulation of daily air temperature and precipitation from monthly normals in North America north of Mexico.

A simple, stochastic daily temperature and precipitation generator (TEMPGEN) was developed to generate inputs for the study of the effects of climate change on models driven by daily weather information when climate data are available as monthly summaries. The model uses as input only 11 sets of monthly normal statistics from individual weather stations. It needs no calibration, and was parameterized and validated for use in Canada and the continental United States. Monthly normals needed are: mean and standard deviation of daily minimum and maximum temperature, first and second order autoregressive terms for daily deviations of minimum and maximum temperatures from their daily means, correlation of deviations of daily minimum and maximum temperatures, total precipitation, and the interannual variance of total precipitation. The statistical properties and distributions of daily temperature and precipitation data produced by this generator compared quite favorably with observations from 708 stations throughout North America (north of Mexico). The algorithm generates realistic seasonal patterns, variability and extremes of temperature, precipitation, frost-free periods and hot spells. However, it predicts less accurately the daily probability of precipitation, extreme precipitation events and the duration of extreme droughts.

Air↗

PubMed1990

Spontaneous formation of pigmentary precipitates in bile salt-depleted rat bile and its prevention by micelle-forming bile salts.

During studies on the effect of bile salt-pool depletion in the bile-fistula rat (adult male Sprague-Dawley), the spontaneous formation of an orange-brown precipitate was noted. The nature of this phenomenon and its relationship to BS and calcium concentration was investigated in depth. Bile from 18 animals was collected in the dark into transparent tubes containing sodium azide, ascorbic acid, and glucaro-1,4-lactone. The tubes were flushed with nitrogen, sealed, and incubated at 37 degrees C. The pigmentary precipitate formed in all the bile salt-depleted (less than 3-5 mM) bile samples (i.e., those collected after 5-7 h of external biliary drainage), but not in bile salt-rich biles. It appeared within 30-240 min after collection, both in bile samples collected at room temperature and at 37 degrees C, initially as a pale flocculation and then slowly sedimenting to form, after centrifugation, a solid, dark-orange pellet. There were no pH changes during incubation, and bile cultures were negative. Under polarizing microscopy, the precipitate appeared amorphous, and there was no evidence of birefringence. High-performance liquid chromatography showed that unconjugated bilirubin was the prevalent pigmentary component, but significant amounts of monoconjugated bilirubin also coprecipitated. Lipid chemistry showed the presence of lecithin (80.1% of total lipids), which was rich in palmitoyl and linoleoyl fatty acids, and of fatty acids (predominantly palmitic and oleic). Infrared spectroscopy and x-ray diffraction showed the presence of calcium bilirubinate and palmitate. In-vivo replenishment of the bile salt pool by intravenous infusion of either taurocholate or taurochenodeoxycholate (1 mumol/min) completely prevented the pigmentary precipitation. In vitro experiments showed inhibition of the precipitate formation by the addition of individual bile salt in concentrations approximating their critical micellar concentration. Precipitate formation was hastened by the addition of calcium chloride (4-12 mM), but only in bile salt-depleted biles. As the composition of the precipitate closely resembles that of human brown-pigment stones and sludge, these findings may provide new insights into an understanding of the pathogenesis of pigment gallstone disease.

Animals↗